GB2624703A

GB2624703A - Sampling apparatus

Info

Publication number: GB2624703A
Application number: GB2217821.4A
Authority: GB
Inventors: Barr Richard; Andersson Sean; Stuart Murray
Original assignee: Proserv UK Ltd
Current assignee: Proserv UK Ltd
Priority date: 2022-11-28
Filing date: 2022-11-28
Publication date: 2024-05-29
Also published as: GB202217821D0

Abstract

Obtaining a composite fluid sample from a flowline (14), using an apparatus (10) comprising: a housing (16); a pressure control barrier (18) movably mounted in the housing; a sample chamber (20) within the housing on a first side of the pressure control barrier (18) and fluidly connectable to the flowline for receiving fluid from the flowline; a pressure control chamber (22) within the housing on an opposite second side of the pressure control barrier, the pressure control chamber comprising an incompressible pressure control fluid (26); and a pressure control arrangement (24) configured to control a volume of the pressure control fluid within the pressure control chamber to permit fluid (12) from the flowline to be received in the sample chamber over multiple time periods to obtain a composite fluid sample. Also disclosed is a sample line purge system 42.

Description

Sampling Apparatus

FIELD

The present disclosure relates to an apparatus and method for sampling a fluid from a flowline. In particular, the present disclosure relates to an apparatus and method for obtaining a composite sample of a fluid from a flowline. Moreover, the present disclosure relates to an apparatus and method for purging a sample line of the flowline.

BACKGROUND

Many industries, such as the oil and gas industry and carbon capture, utilisation and storage (CCUS) industry, manage the flow of fluids through flowlines. It can often be desirable to take a sample of the fluid in such flowlines for processing and testing. Moreover, it can be desirable to combine a number of discrete volumes of fluid, which may be taken over the course of a longer duration of time, into one composite fluid sample.

SUMMARY

An aspect of the present disclosure relates to an apparatus for obtaining a composite fluid sample from a flowline, the apparatus comprising: a housing; a pressure control barrier movably mounted in the housing; a sample chamber within the housing on a first side of the pressure control barrier and being fluidly connectable to the flowline for receiving fluid from the flowline; a pressure control chamber within the housing on an opposite second side of the pressure control barrier, the pressure control chamber comprising an incompressible pressure control fluid; and a pressure control arrangement configured to control a volume of the pressure control fluid within the pressure control chamber to permit fluid from the flowline to be received in the sample chamber over multiple time periods to obtain a composite fluid sample.

The pressure control fluid may be configured to provide a back pressure against the flow of fluid into the sample chamber from the flowline. A volume of the pressure control fluid in the pressure control chamber may be modified by the pressure control arrangement to control movement of the pressure control barrier and allow the volume of the sample chamber to expand and fluid from the flowline to be received in the sample chamber. The pressure control arrangement may be configured to control a rate at which fluid from the flowline is received in the sample chamber, which may allow the fluid received in the sample chamber to be maintained at or near flowline pressure.

The provision of an incompressible fluid in the pressure control chamber may provide for improved control over the position of the pressure control barrier in the housing. For example, by maintaining a constant volume of incompressible fluid in the pressure control chamber, the position of the pressure control barrier may be maintained at a constant position within the housing irrespective of an increase in pressure in the sample chamber. Moreover, a volume of the incompressible pressure control fluid displaced from the pressure control chamber may be used to determine the volume of fluid received in the sample chamber. As defined herein, an incompressible fluid may be a fluid whose volume or density is independent of pressure. Thus, the pressure control fluid may not experience a change in volume (or will at most experience a negligible change in volume) when subjected to an increase in pressure by fluid in the sample chamber. For instance, the pressure control fluid may comprise a liquid. In some examples, the pressure control fluid may comprise glycol. In other examples, the pressure control fluid may comprise a mixture of glycol and water. However, it will be appreciated that the pressure control fluid may comprise any other suitable fluid known in the art.

Any decrease in pressure of the fluid entering the sample chamber may alter the composition of the fluid. It is therefore important that the pressure of the fluid is maintained at or near flowline pressure during the sampling process so that the fluid received in the sample chamber is of the same composition as the fluid in the flowline.

In this regard, the apparatus may be particularly beneficial for use in sampling a gas from a flowline, since the properties of certain gases can be particularly sensitive to changes in pressure.

The multiple time periods in which fluid is received in the sample chamber may comprise first and second time periods. The second time period may start a duration of time after the first time period has ended. A first discrete volume of fluid may be received in the sample chamber during the first time period. A second discrete volume of fluid may be received in the sample chamber during the second time period. The duration of time between receiving the first and second volumes of fluid may be in the order of seconds, minutes, hours, days, etc. In some examples, a fluid sample may be obtained every minute, e.g. over a period of 24 hours.

The first and second volumes of fluid may have different properties from one another, e.g. pressure, temperature, density, viscosity, etc. When the second volume of fluid is received in the sample chamber, the second volume of fluid may combine with the first volume of fluid forming the composite fluid sample. Certain properties of the composite fluid sample may represent a function of the corresponding properties of the first and second volumes of fluid received in the sample chamber. For example, where the first and second volumes of fluid comprise the same volume, the composite fluid sample may represent an average of the properties of the first and second volumes of fluid. In other examples, however, the first and second volumes of fluid may comprise different volumes of fluid.

While the discussion above refers to the composite fluid sample comprising first and second volumes of fluid, it will be appreciated that the composite fluid sample may comprise any other number of volumes of fluid, e.g. three or more volumes of fluid.

The flowline may be associated with wellbore operations, such as the production of hydrocarbons and associated components (such as water, solids, etc.) from a wellbore, the injection of fluids (e.g., water, gas etc.) into a wellbore, and the like. In this respect, the apparatus may be for sampling a fluid from a well flowline.

The flowline may be associated with a carbon capture, utilisation and storage (CCUS) operation. The apparatus may be configured to sample a gas (e.g. carbon dioxide) from a flowline. The apparatus disclosed herein may have particular utility in CCUS operations where the analysis of the gas may be critical for identifying impurities. Moreover, due to the supercritical nature of carbon dioxide, the density (and sometimes state) of carbon dioxide is particularly sensitive to small changes in pressure.

The flowline may be located at an onshore location, offshore location, topside location, subsea location, subterranean location and/or the like.

The fluid in the flowline may be at any pressure depending on the application of the apparatus. However, where the apparatus is used in a CCUS operation, the flowline may comprise a pressure in the region of 150 bar. It will be appreciated, however, that the apparatus may be equally used in any number of other applications outside of the oil and gas or CCUS industries.

The pressure control chamber may comprise a pressure control outlet. The pressure control arrangement may be provided in fluid communication with the pressure control chamber, e.g. via the pressure control outlet. The pressure control arrangement may be configured to permit a predetermined volume of the pressure control fluid to be displaced from the pressure control chamber such that a corresponding volume of fluid from the flowline is received in the sample chamber.

The pressure control arrangement may be configured for automatic operation or use from a remote location. The pressure control arrangement may comprise one or more monitoring devices. The one or more monitoring devices may be configured to indicate a volume of the pressure control fluid that has passed through the pressure control arrangement, which may provide an indication of a position of the pressure control barrier within the housing and thus a volume of fluid sample in the sample chamber.

The apparatus may comprise a control module. The control module may be configured to control the pressure control arrangement. The control module may comprise a controller, such as a programmable logic controller (PLC) or the like. In particular, the control module may be configured to control the pressure control arrangement to modify the volume of the pressure control fluid in the pressure control chamber to receive fluid from the flowline in the sample chamber as described above.

The control module may be configured to receive a signal indicative of a pressure in at least one of the flowline, the sample chamber and the pressure control chamber. The control module may be configured to control the pressure control arrangement to operate in accordance with one or more of the received pressure signals. The control module may be configured to monitor and control a pressure of the pressure control fluid within the pressure control chamber.

The pressure control arrangement may be configured to allow fluid from the flowline to enter the sample chamber and displace the pressure control fluid from the pressure control chamber at a certain frequency, stroke (e.g., volume) size and/or flowrate, e.g. to maintain the fluid entering the sample chamber at or near flowline pressure. In some examples, the pressure control arrangement may be configured to permit fluid from the flowline to displace the pressure control fluid from the pressure control chamber at a flowrate of 3 millilitres per second. However, in other examples, any other suitable flowrate may be used.

The pressure control arrangement may comprise a pump. The pump may be in fluid communication with the pressure control chamber. The provision of a pump in fluid communication with the pressure control chamber (e.g. as opposed to being in fluid communication with the sample chamber or flowline) has a number of advantages. For example, the risk of the fluid sample being contaminated from seals, pump lubricant, etc., is minimised or eliminated. The risk of the pump being impacted by solids from the flowline is minimised or eliminated. Further, the risk of the fluid dropping in pressure through a pump housing is reduced. In some examples, the pump may be run on instrument air, by solar, batteries, electrical supply, etc. The pump may be configured to pump the pressure control fluid from the pressure control chamber to modify the volume of the pressure control fluid in the pressure control chamber. The pump may be configured to pump the pressure control fluid from the pressure control chamber at a certain frequency, stroke (volume) size and/or flowrate, e.g. to maintain the fluid entering the sample chamber at or near flowline pressure. In some examples, the pump may be configured to pump the pressure control fluid from the pressure control chamber at a flowrate of 3 millilitres per second. However, in other examples, any other suitable flowrate may be used.

The pump may be configured to maintain a pressure within the pressure control chamber to maintain the pressure control barrier at a constant position within the housing The pump may be configured to be controlled by the control module. The pump may be any type of suitable pump known in the art, e.g. a positive displacement pump.

Alternatively or in addition to comprising a pump, the pressure control arrangement may comprise one or more pressure control valves, e.g. choke valves. The one or more pressure control valves may be configured to control a rate at which the pressure control fluid is displaced from the pressure control chamber. The one or more pressure control valves (when closed) may be configured to maintain a pressure within the pressure control chamber to maintain the pressure control barrier at a constant position in the housing. A dimension of the valve may be selected to provide a particular flow regime as the pressure control fluid exits the pressure control chamber through the valve.

In other examples, the pressure control arrangement may comprise an accumulator.

In some examples, the pressure control arrangement may be configured to deliver or re-introduce the pressure control fluid into the pressure control chamber, e.g. to reduce the size of the sample chamber and displace a fluid sample from the pressure control chamber. Alternatively or additionally, a dedicated filling port may be provided on the housing for the pressure control fluid to be delivered to the pressure control chamber.

In some examples, the apparatus may be provided pre-charged with pressurised pressure control fluid.

The housing may comprise a housing bore. The pressure control barrier may be mounted within the housing bore. The housing bore may be cylindrical. The housing bore may define the volume of the housing. The housing may comprise a cylinder, for example provided by a tubular body. The housing may be formed of any suitable material, such as a metal or metal alloy, a composite material, a polymer, etc. The pressure control barrier may define a shape complimentary to the housing bore.

The housing may be sized in accordance with the total volume of the fluid sample to be received from the flowline. Additionally or alternatively, the housing may be sized in accordance with the volume of pressure control fluid in the pressure control chamber required to provide sufficient control over the flow of fluid entering the sample chamber. In some examples, the housing may be sized such that the sample chamber can receive 0.5 litres, 1 litre, 2 litres, 4 litres, 8 litres, etc., of fluid from the flowline.

The housing may comprise one or more drain ports. The drain ports may be arranged along a length of the housing. The drain ports may permit one or more sub-samples of fluid to be taken from the sample chamber. This may permit a sub-sample of the fluid to be removed, permitting individual processing and testing of sub-samples if required.

This may allow the sub-sample to be certified at the location of sampling for certain types of transportation, as well as enabling samples to be allocated for certain types of full-composition laboratory tests. A measurement device may be provided for connection to the apparatus, e.g. one or more of the side ports of the apparatus. The measurement device may be configured to determine certain properties of the fluid sample adjacent the side port.

It is noted that any reference herein to "tor', "down", "upper" or "lower" should be understood as in relation to gravity when the apparatus is in use.

The pressure control barrier may comprise a piston member. The pressure control barrier may comprise a disc piston. The pressure control barrier may comprise a vane piston. The pressure control barrier may be configured for sliding engagement with an inner surface of the housing. The pressure control barrier may comprise one or more bearing surfaces to facilitate sliding engagement.

The pressure control barrier may comprise an outer sealing arrangement configured to seal against an inner surface of the housing. The sealing arrangement may be configured to create a seal between the sample chamber and pressure control chamber such that any fluid received in the sample chamber is prevented from entering the pressure control chamber. The sealing arrangement may comprise dynamic seals to permit the required relative movement of the pressure control barrier in the housing. The sealing arrangements may be bi-directional to ensure isolation of any pressure differential across the piston in reverse directions. The sealing arrangements may comprise one or more sealing members, such as 0-rings, chevron seal stacks, piston rings and/or the like.

The pressure control barrier may comprise a position indicator. The position indicator may indicate a position of the pressure control barrier in the housing. In one example, the position indicator may comprise a magnet fixed to the pressure control barrier. The magnet may be configured to move a follower located externally on the housing (or at least visible externally of the housing), such that the follower indicates the position of the pressure control barrier in the housing. However, other known position indicators may alternatively or additionally be used.

The pressure control arrangement may comprise a receptacle. The receptacle may be configured to receive the pressure control fluid displaced from the pressure control chamber. The volume of the pressure control fluid received in the receptacle may correspond to the volume of fluid sample received in the sample chamber, such that a volume of fluid received in the sample chamber may be determined by monitoring a volume of pressure control fluid in the receptacle. The receptacle may be provided with means for determining a volume of fluid within the receptacle. Such means may comprise one or more sensors (e.g. for automatic or remote operation of the apparatus) or visual means, such as a graduated scale showing the volume of fluid within the receptacle. In addition, the provision of such a receptacle means that there may be no discharge of the pressure control fluid to atmosphere, which may allow for the pressure control fluid to be reused The apparatus may be connectable to a sample line (e.g. a pipe branch) extending from the flowline. The sample chamber may be fluidly connectable to the sample line of the flowline.

The sample chamber may comprise a sample inlet. The sample inlet may be located towards an upper region of the apparatus. For example, the sample inlet may be located on an upper surface of the housing. Alternatively, the sample inlet may be located on a side surface of the housing. The sample inlet may be connectable to the sample line of the flowline. The sample line may comprise a smaller volume than a volume of the housing. In one example, the sample line may comprise a total volume of no more than 100 millilitres.

The sample inlet may be configured to permit fluid from the flowline to enter the sample chamber via the sample line of the flowline. The sample inlet may be selectively openable. The sample inlet may comprise one or more sample inlet valves. The one or more sample inlet valves may be configured to close between the time periods in which fluid is received in the sample chamber. In some examples, the one or more sample inlet valves may comprise a non-return valve. The sample inlet may comprise a port or an orifice. In one example, the sample inlet may also be configured to depressurise the sample chamber, i.e. when the apparatus is disconnected from the flowline. In other examples, however, the apparatus may alternatively or additionally be provided with a separate depressurisation port or valve.

The pressure control barrier may be provided in an initial position within the housing such that a major portion of the housing bore is occupied by the pressure control chamber and a minor portion of the housing bore is occupied by the sample chamber.

In other examples, the pressure control barrier may be provided within the housing such that all of the housing bore is occupied by the pressure control chamber and no sample chamber is present in the housing initially.

When the apparatus is initially connected to the sample line, there may be initial contents in the sample line that need to be purged or displaced from the sample line before a fluid sample is received in the sample chamber. Additionally, if the initial position of the pressure control barrier is such that the sample chamber is present in the housing initially, there may also be initial contents in the sample chamber that need to be purged or displaced before a fluid sample is received in the same chamber.

Therefore, while the following description refers to the initial contents being in the sample line only, such description should be understood as including the initial contents being in both the sample line and the sample chamber where the sample chamber is present in the housing initially.

The initial contents of the sample line may comprise one or more contaminants or pollutants (such as, air) mixed with fluid from the flowline, which if not properly purged before receiving a fluid sample in the sample chamber may contaminate the fluid sample and modify its composition. Thus, in order to purge the sample line of its initial contents, fluid from the flowline may be allowed to enter the sample line to displace (e.g. flush or purge) the initial contents of the sample line (e.g. by opening a valve to allow fluid from the flowline to enter the sample line).

In some examples, the volume of fluid for displacing the contents of the sample line may be equal to or more than the volume of the sample line. For example, where the sample line comprises a volume of 100 millilitres, 300 millilitres of fluid from the flowline may be flushed through the sample line to ensure all the contents of the sample line have been displaced before a fluid is received in the sample chamber. Once the purging process has been completed, i.e. once the initial contents of the sample line have been fully displaced, a fluid sample may be received in the sample chamber.

The apparatus may comprise a purging arrangement. The purging arrangement may be configured to control a rate at which the initial contents of the sample line are displaced from the sample line, which may allow a pressure in the sample line to be maintained at or near flowline pressure as the initial contents are displaced from the sample line. Therefore, fluid from the flowline that remains in the sample line after the purging process has been completed will have been maintained at the same pressure as the fluid in the flowline. This may further improve the quality of the fluid sample received in the sample chamber since if the fluid sample combines with fluid remaining in the sample line after the purging process been completed, the entirety of the resulting fluid sample will have been maintained at or near flowline pressure throughout both the purging and sampling processes.

In some examples, the purging arrangement may also be configured to maintain the initial contents of the sample line at or near flowline temperature during the purging process.

The purging arrangement may comprise a similar structure to the apparatus for receiving fluid samples described hereinabove. In particular, the purging arrangement may comprise a housing. A pressure control barrier may be movably mounted in the housing. A purge chamber may be provided within the housing on a first side of the pressure control barrier. The purge chamber may be fluidly connectable to at least one of the sample line and sample chamber for receiving the contents of the sample line. A purge pressure control chamber may be provided in the housing on an opposite second side of the pressure control barrier. The purge pressure control chamber may comprise a purge pressure control fluid.

The purging arrangement may comprise a purge pressure control arrangement. A volume of the purge pressure control fluid in the purge pressure control chamber may be modified by the purge pressure control arrangement to control movement of the pressure control barrier to allow the initial contents from the sample line to be received in the purge chamber as the volume of the purge chamber expands. The purge pressure control arrangement may thus be configured to control a rate at which the initial contents from the sample line are received in the purge chamber.

The purge pressure control arrangement may be configured for automatic operation or use from a remote location. The purge pressure control arrangement may comprise one or more monitoring devices. The one or more monitoring devices may be configured to indicate a volume of the purge pressure control fluid that has passed through the purge pressure control arrangement, which may provide an indication of a position of the pressure control barrier within the housing and thus a volume of fluid in the purge chamber.

The purging arrangement may be configured to be controlled by the control module.

The control module may be configured to control the purge pressure control arrangement to modify a volume of the purge pressure control fluid in the purge pressure control chamber to receive the initial contents of the sample line in the purge chamber as described above. The control module may be configured to receive a signal indicative of a pressure in at least one of the flowline, the purge chamber and the purge pressure control chamber. The control module may be configured to control the purge pressure control arrangement to operate in accordance with one or more of the received pressure signals.

The purge pressure control fluid may comprise an incompressible fluid. The purge pressure control fluid may comprise a liquid, e.g. an incompressible liquid. The provision of an incompressible fluid in the purge pressure control chamber may provide for improved control over the position of the pressure control barrier in the housing.

The purge pressure control arrangement may comprise a receptacle. The receptacle may be configured to receive the purge pressure control fluid displaced from the purge pressure control chamber. The volume of the purge pressure control fluid received in the receptacle may correspond to the volume of the initial contents of the sample line (and fluid from the flowline used to displace the initial contents of the sample line) received in the purge chamber. The receptacle may be provided with means for determining a volume of fluid within the receptacle. Such means may comprise one or more sensors (e.g. for automatic or remote operation of the apparatus) or visual means, such as a graduated scale showing the volume of fluid within the receptacle. In addition, the provision of such a receptacle means that there may be no discharge of the pressure control fluid to atmosphere, which may allow for the pressure control fluid to be reused The purge pressure control arrangement may comprise a pump. The pump may be in fluid communication with the purge pressure control chamber. The pump may be configured to pump the purge pressure control fluid from the purge pressure control chamber to modify a volume of the purge pressure control fluid in the purge pressure control chamber. The pump may be configured to pump the purge pressure control fluid from the purge pressure control chamber at a certain frequency, stroke (volume) size and/or flowrate, e.g. to maintain a pressure in the sample line at or near flowline pressure. Alternatively or in addition to comprising a pump, the purge pressure control arrangement may comprise one or more pressure control valves, e.g. choke valves.

The apparatus may comprise a purge outlet. The purge outlet may be configured to allow the initial contents of the sample line to be displaced (e.g. flushed or purged) from the sample line and received by the purging arrangement. The purge outlet may be provided downstream of the sample inlet. The purge outlet may be provided in fluid communication with the sample chamber. The sample inlet and purge outlet may be aligned (e.g. vertically aligned) with one another. The purge outlet may be located towards an upper region of the housing. The purge outlet may be located on a side surface of the housing.

One or more purge outlet valves may be provided downstream of the sample inlet. When it is desired to purge the sample line of its initial contents, the sample inlet valve(s) and the purge outlet valve(s) may be opened to allow fluid to flow from the flowline through the sample line and displace the initial contents of the sample line. Meanwhile, the volume of the pressure control fluid in the pressure control chamber may be maintained constant to prevent fluid from the flowline expanding the sample chamber.

The purge outlet valve(s) may be located on a part of the sample line. The purge outlet valve(s) may be located on a part of the sample line connecting the sample chamber and purge chamber. In some examples, the purge outlet valve(s) may comprise a non-return valve. The purge outlet valve(s) may be configured to close after the purging operation has been completed to prevent any backflow of the initial contents of the sample line.

A flow path for the initial contents of the sample line to travel to the purging arrangement may extend from the flowline to the purging arrangement. In one example, a portion of the flow path may extend across the sample inlet of the sample chamber. In other examples, a portion of the flow path may extend through (i.e. within) the sample chamber. Such configurations may help minimise contamination.

In some examples, the housing may comprise a stop member, such as an inner protrusion. The stop member may be configured to limit movement of the pressure control barrier within the housing to prevent the pressure control chamber from occupying all of the housing when the pressure control barrier is in the initial position.

The apparatus may comprise a filtration device. The filtration device may be located upstream of the sample chamber, e.g. in the sample inlet or at a point along the sample line. The filtration device may be configured to prevent solids or unwanted particles from entering the sample chamber.

In one example, the purge outlet may also be configured to depressurise the sample chamber, e.g. when a fluid sample is to be removed from the sample chamber. In other examples, however, the apparatus may alternatively or additionally be provided with a separate depressurisation port(s) or valve(s).

The apparatus (e.g. sample chamber, pressure control chamber, sample line and/or purging arrangement) may be provided with means for maintaining or modifying a temperature of fluid from the flowline. For example, a thermal jacket, blanket, tape, etc., may be suitably provided to maintain and/or modify a temperature of at least one of the initial contents of the sample line, fluid in the sample chamber, the pressure control fluid and the purge pressure control fluid, e.g. to maintain flowline temperature during the purging and/or sampling processes.

The apparatus may comprise one or more pressure relief valves to prevent over-pressurisation of the sample chamber, pressure control chamber, purge chamber and/or purge pressure control chamber above a certain value. The apparatus may be provided with a gauge for indicating a pressure and/or temperature inside the sample chamber, pressure control chamber, purge chamber and/or purge pressure control chamber.

The apparatus may comprise a stand assembly, to permit appropriate self-support of the apparatus in a desired orientation. In some examples, the sampling apparatus may be configured to be mounted on the flowline, for example via a clamping system, strap system, etc. In some examples, a number of apparatus in accordance with the present disclosure may be provided together for sampling a fluid from a flowline. For example, in one configuration, a first apparatus may be connected to the flowline and a second apparatus may be connected to the flowline, e.g. via the first apparatus, wherein a purging arrangement may be connected to at least one of the first and second apparatus. This may enable separate volumes of samples to be obtained over longer periods of time.

An aspect of the present disclosure relates to a method for obtaining a composite fluid sample from a flowline, comprising: providing an apparatus comprising a housing, a pressure control barrier movably mounted in the housing, a sample chamber within the housing on a first side of the pressure control barrier and a pressure control chamber within the housing on an opposite second side of the pressure control barrier, the pressure control chamber comprising an incompressible pressure control fluid; fluidly connecting the sample chamber to the flowline; controlling a volume of the pressure control fluid in the pressure control chamber to permit a first discrete volume of fluid to be received in the sample chamber from the flowline; and controlling the volume of the pressure control fluid in the pressure control chamber to permit a second discrete volume of fluid to be received in the sample chamber from the flowline.

The method may comprise receiving three or more discrete volumes of fluid in the sample chamber.

The method may comprise modifying a volume of the pressure control fluid in the pressure control chamber to control movement of the pressure control barrier to allow the volume of the sample chamber to expand and fluid from the flowline to be received in the sample chamber.

The method may comprise reducing the volume of the pressure control fluid in the pressure control chamber to achieve an acceptable flowrate of fluid flow into the sample chamber to maintain the fluid at or near flowline pressure.

The method may comprise displacing the pressure control fluid from the pressure control chamber.

The method may comprise receiving a predetermined volume of fluid from the flowline in the sample chamber and displacing a corresponding volume of the pressure control fluid from the pressure control chamber.

The method may comprise controlling a pressure of the pressure control fluid based on a signal indicative of a pressure in at least one of the flowline, the sample chamber and the pressure control chamber.

The method may comprise pumping the pressure control fluid from the pressure control chamber to modify the volume of the pressure control fluid in the pressure control chamber.

The method may comprise receiving the pressure control fluid from the pressure control chamber in a receptacle. The method may comprise determining a volume of fluid received in the sample chamber based on the volume of the pressure control fluid received in the receptacle.

The method may comprise providing the pressure control barrier in an initial position within the housing such that a major portion of the housing bore is occupied by the pressure control chamber and a minor portion of the housing bore is occupied by the sample chamber. The method may comprise providing the pressure control barrier in an initial position within the housing such that all of the housing bore is occupied by the pressure control chamber and no sample chamber is present in the housing initially.

The method may comprise connecting the apparatus (e.g. a sample inlet of the sample chamber) to a sample line of the flowline, wherein the sample line may comprise initial contents to be purged from the sample line before fluid from the flowline is received in the sample chamber.

The method may comprise, before the step above of controlling the volume of the pressure control fluid in the pressure control chamber to permit a first volume of fluid to be received in the sample chamber from the flowline, purging the sample line. Purging the sample line may comprise allowing fluid from the flowline to enter the sample line to displace the initial contents of the sample line. The method may comprise controlling a rate at which the initial contents of the sample line are displaced from the sample line.

The method may comprise maintaining a pressure in the sample line at or near flowline pressure as the initial contents are displaced from the sample line.

The method may comprise displacing a purge pressure control fluid from a purge pressure control chamber while receiving the initial contents of the sample line in a purge chamber. The method may comprise controlling a volume of a purge pressure control fluid inside the purge pressure control chamber to control a rate at which the initial contents of the sample line are displaced from the sample line.

The method may comprise flowing the initial contents of the sample line across the sample inlet. The method may comprise flowing the initial contents of the sample line through the sample chamber.

The method may comprise maintaining the pressure within the pressure control chamber at the same pressure or a higher pressure than the flowline pressure during the purging process to prevent the sample chamber from expanding.

The method may comprise filtering the fluid sample from the flowline before receiving fluid sample in the sample chamber.

Another aspect of the present disclosure relates to an apparatus for purging a sample line of a flowline and obtaining a fluid sample from the flowline, wherein the sample line comprises initial contents to be purged from the sample line before fluid from the flowline is sampled, the apparatus comprising: a sample chamber fluidly connectable to the sample line for receiving a fluid sample from the flowline; and a purging arrangement configured to control a pressure inside the sample line as the initial contents of the sample line are purged from the sample line.

Fluid from the flowline may be allowed to enter the sample line to displace the initial contents of the sample line. The purging arrangement may be configured to control a rate at which the initial contents of the sample line are displaced from the sample line, which may allow a pressure in the sample line to be maintained at or near flowline pressure as the initial contents are displaced from the sample line.

The purging arrangement may comprise a similar structure to the apparatus for receiving fluid samples described hereinabove. In particular, the purging arrangement may comprise a housing. A pressure control barrier may be movably mounted in the housing. A purge chamber may be provided within the housing on a first side of the pressure control barrier. The purge chamber may be fluidly connectable to at least one of the sample line and sample chamber for receiving the contents of the sample line. A purge pressure control chamber may be provided in the housing on an opposite second side of the pressure control barrier. The purge pressure control chamber may comprise a purge pressure control fluid. The purge pressure control fluid may comprise an incompressible fluid. The purge pressure control fluid may comprise a liquid, e.g. an incompressible liquid.

Another aspect of the present disclosure relates to an apparatus for purging a sample line of a flowline and obtaining a fluid sample from the flowline, wherein the sample line comprises initial contents to be purged from the sample line before fluid from the flowline is sampled, the apparatus comprising: a sample chamber fluidly connectable to the sample line for receiving a fluid sample from the flowline; and a purging arrangement, the purging arrangement comprising: a housing; a pressure control barrier movably mounted in the housing; a purge chamber within the housing on a first side of the pressure control barrier, the purge chamber fluidly connectable to at least one of the sample line and the sample chamber for receiving the initial contents of the sample line; a purge pressure control chamber in the housing on an opposite second side of the pressure control barrier, the purge pressure control chamber comprising a purge pressure control fluid; and a purge pressure control arrangement configured to control a volume of the purge pressure control fluid within the purge pressure control chamber to control a rate at which the initial contents of the sample line are received in the purge chamber.

The purge pressure control fluid may be configured to provide a back pressure against the flow of the initial contents into the purge chamber from the sample line. A volume of the purge pressure control fluid in the purge pressure control chamber may be modified by the purge pressure control arrangement to control movement of the pressure control barrier and allow the initial contents from the sample line to be received in the purge chamber as the volume of the purge chamber expands. The purge pressure control arrangement may thus be configured to control a rate at which the initial contents from the sample line are received in the purge chamber. This may allow fluid from the flowline that remains in the sample line after the purging process has been completed to have been maintained at or near flowline pressure. This may improve the quality of the fluid sample received in the sample chamber since if the fluid sample combines with fluid remaining in the sample line and/or sample chamber after the purging process been completed, the entirety of the resulting fluid sample will have been maintained at or near flowline pressure throughout both the purging and sampling processes.

The purge pressure control arrangement may comprise a receptacle. The receptacle may be configured to receive the purge pressure control fluid displaced from the purge pressure control chamber. The volume of the purge pressure control fluid received in the receptacle may correspond to the volume of the initial contents of the sample line (as well as any fluid from the flowline used to displace the initial contents of the sample line) received in the purge chamber. The receptacle may be provided with means for determining a volume of the contents within the receptacle. Such means may comprise one or more sensors (e.g. for automatic or remote operation of the apparatus) or visual means, such as a graduated scale showing the volume of fluid within the receptacle. In addition, the provision of such a receptacle means that there may be no discharge of the pressure control fluid to atmosphere, which may allow for the pressure control fluid to be reused.

The purge pressure control arrangement may comprise a pump. The pump may be in fluid communication with the purge pressure control chamber. The pump may be configured to pump the purge pressure control fluid from the purge pressure control chamber to modify a volume of the purge pressure control fluid. The pump may be configured to pump the purge pressure control fluid from the purge pressure control chamber at a certain frequency, stroke (volume) size and/or flowrate, e.g. to maintain the fluid entering the purge chamber at or near flowline pressure. Alternatively or in addition to comprising a pump, the purge pressure control arrangement may comprise one or more pressure control valves, e.g. choke valves.

The sample chamber may comprise a sample inlet. The sample inlet may be connectable to the sample line of the flowline. The sample chamber may comprise a purge outlet. The purging arrangement may be connectable to the purge outlet. The purge outlet may be configured to allow the initial contents of the sample line to be displaced from the sample line, through the sample chamber and received by the purging arrangement. In this way, where the sample chamber also comprises initial contents to be purged, the initial contents of the sample chamber may be displaced from the sample chamber and received in the purge chamber.

The purging arrangement may be configured to maintain the initial contents of the sample line at constant temperature during the purging process. For example, a thermal jacket, blanket, tape, etc., may be provided to maintain and/or modify a temperature of the initial contents of the sample line.

The sample chamber may be comprised within an apparatus for sampling fluids according to the description hereinabove. As such, the sample chamber may be provided in a housing on a first side of a pressure control barrier. A pressure control chamber may be provided within the housing on an opposite second side of the pressure control barrier, the pressure control chamber comprising an incompressible pressure control fluid. A pressure control arrangement may be configured to control a volume of the pressure control fluid within the pressure control chamber to permit fluid from the flowline to be received in the sample chamber over multiple time periods to obtain a composite fluid sample.

Another aspect of the present disclosure relates to a method for purging a sample line of a flowline and obtaining a fluid sample from the flowline, wherein the sample line comprises initial contents to be purged from the sample line before fluid from the flowline is sampled, the method comprising: fluidly connecting a sample chamber to the sample line for receiving a fluid sample from the flowline; fluidly connecting a purging arrangement to at least one of the sample line and the sample chamber; allowing fluid from the flowline to enter the sample line to displace the initial contents of the sample line; controlling with the purging arrangement a rate at which the initial contents of the sample line are displaced from the sample line; and receiving a fluid sample in the sample chamber.

Another aspect of the present disclosure relates to a method for purging a sample line of a flowline and obtaining a fluid sample from the flowline, wherein the sample line comprises initial contents to be purged from the sample line before fluid from the flowline is received in sampled, the method comprising: fluidly connecting a sample chamber to the sample line for receiving a fluid sample from the flowline; providing a purging arrangement comprising a housing, a pressure control barrier movably mounted in the housing, a purge chamber within the housing on a first side of the pressure control barrier, and a purge pressure control chamber in the housing on an opposite second side of the pressure control barrier, the purge pressure control chamber comprising a purge pressure control fluid; fluidly connecting the purge chamber to at least one of the sample line and the sample chamber for receiving the initial contents of the sample line; allowing fluid from the flowline to enter the sample line to displace the initial contents of the sample line; controlling a rate at which the initial contents of the sample line are received in the purge chamber; and receiving a fluid sample in the sample chamber.

An aspect of the present disclosure relates to an apparatus for sampling a fluid from a flowline, the apparatus comprising: a housing; a pressure control barrier movably mounted in the housing; a sample chamber within the housing on a first side of the pressure control barrier and being fluidly connectable to the flowline for receiving a fluid sample from the flowline; a pressure control chamber within the housing on an opposite second side of the pressure control barrier, wherein pressure applied within the pressure control chamber controls pressure of the fluid sample within the sample chamber; and a pressure control arrangement configured to control the pressure within the pressure control chamber to permit fluid samples to be received in the sample chamber.

The apparatus may comprise a purging arrangement according to the description hereinabove.

It should be understood that features defined in relation to one aspect may be provided in combination with any other aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1 to 3 are diagrammatic illustrations of an apparatus performing a sampling process in which a fluid from a flowline is being sampled; Figures 4 and 5 are diagrammatic illustrations of the apparatus comprising a purging arrangement; Figures 6 and 7 are diagrammatic illustrations of the apparatus performing a sampling process in which a fluid from a flowline is being sampled; Figure 8 is a perspective view of the apparatus; and Figures 9 to 12 are diagrammatic illustrations of an alternative apparatus and purging arrangement.

DETAILED DESCRIPTION OF THE DRAWINGS

Figures 1 to 4 are diagrammatic illustrations of an apparatus 10 performing a sampling process in which a fluid 12 from a flowline 14 is sampled. The flowline 14 may be associated with wellbore operations, such as the production of hydrocarbons and associated components (such as water, solids etc.) from a wellbore, the production of water from a wellbore, the injection of fluids (e.g., water, gas etc.) into a wellbore, and the like. In this respect, the apparatus 10 may be for sampling a fluid from a well flowline 14. Alternatively, the flowline 14 may be associated with a carbon capture, utilisation and storage (CCUS) operation and configured to sample a gas (e.g. comprising carbon dioxide) from a flowline 14. The apparatus 10 disclosed herein may have particular utility in CCUS operations, where the analysis of the gas may be critical for identifying impurities. The fluid in the flowline 14 may be at any pressure and temperature depending on the application. In one example application, where the apparatus 10 is used in a CCUS operation, the flowline 14 may comprise a pressure of around 150 bar. It will be appreciated here, however, that the apparatus 10 may be equally used in any number of other applications outside of the oil and gas or CCUS industries.

The apparatus 10 comprises a housing 16 with a pressure control barrier 18 movably mounted in the housing 16. A sample chamber 20 is provided within the housing 16 on a first side of the pressure control barrier 18 and is fluidly connected to the flowline 14 for receiving fluid 12 from the flowline 14. A pressure control chamber 22 is provided within the housing 16 on an opposite second side of the pressure control barrier 18. The pressure control chamber 22 comprises an incompressible pressure control fluid 26. A pressure control arrangement 24 is configured to control a volume of the pressure control fluid 26 within the pressure control chamber 22 to permit fluid 12 from the flowline 14 to be received in the sample chamber 20 over multiple time periods to obtain a composite fluid sample. The pressure control arrangement 24 controls a rate at which fluid is received within the sample chamber 20 to maintain the fluid at or near flowline pressure. This may mitigate or prevent properties of the fluid from changing during the process of receiving the fluid 12 in the sample chamber 20. In particular, any decrease in pressure of the fluid during the sampling process may irreversibly alter the composition of the fluid. It is therefore important that the pressure of the fluid is maintained at or near flowline pressure during the sampling process so that the composition of the fluid received in the sample chamber 20 corresponds to the fluid composition in the flowline 14.

The pressure control arrangement 24 is configured to permit fluid from the flowline to displace a predetermined volume of the pressure control fluid 26 from the pressure control chamber 22 via a pressure control outlet of the pressure control chamber 22.

The provision of an incompressible fluid in the pressure control chamber 22 may provide for improved control over the position of the pressure control barrier 18 in the housing 16. For example, by maintaining a constant volume of the incompressible pressure control fluid 26 in the pressure control chamber 22, the position of the pressure control barrier 18 can be maintained at a constant position within the housing 16 irrespective of an increase in pressure in the sample chamber 20. Moreover, a volume of the incompressible pressure control fluid 26 displaced from the pressure control chamber 22 may be used to determine the volume of fluid received in the sample chamber 20. In some examples, the pressure control fluid 26 may comprise glycol. In other examples, the pressure control fluid 26 may comprise a mixture of glycol and water. However, it will be appreciated that the pressure control fluid 26 may comprise any other suitable fluid known in the art.

The pressure control fluid 26 is configured to provide a particular back pressure against the flow of fluid into the sample chamber 20 from the flowline 14. The back pressure may help to maintain a constant pressure of fluid as the fluid enters the sample chamber, enabling the fluid to be sampled at the same pressure as the fluid 12 in the flowline 14.

In this example, the pressure control arrangement 24 comprises a pump 30 in fluid communication with the pressure control chamber 22. The provision of a pump 30 in fluid communication with the pressure control chamber 22 (e.g. as opposed to being in fluid communication with the sample chamber) has a number of advantages. For example, the risk of the fluid sample being contaminated from seals, pump lubricant, etc., is minimised or eliminated. The risk of the pump 30 being impacted by solids from the flowline 14 is minimised or eliminated. Further, the risk of fluid 12 dropping in pressure through a pump housing is reduced.

The pressure control arrangement 24 is configured to permit fluid from the flowline to displace the pressure control fluid 26 from the pressure control chamber 22 at a certain frequency, stroke (e.g., volume) size and/or flowrate, such that fluid is received in the sample chamber 20 while maintaining flowline 14 pressure. In this example, the pressure control arrangement 24 further comprises a pressure control valve 32, e.g. a choke valve. The pump 30 and/or pressure control valve 32 may be configured to maintain a pressure within the pressure control chamber 22 to maintain the pressure control barrier 18 at a constant position within the housing 16.

The pressure control arrangement 24 comprises a receptacle 34 for receiving the pressure control fluid 26 displaced from the pressure control chamber 22. The volume of the pressure control fluid 26 received in the receptacle 34 corresponds to the volume of fluid received in the sample chamber, such that a volume of fluid received in the sample chamber 20 may be determined by monitoring a volume of pressure control fluid 26 in the receptacle 34. In addition, the provision of such a receptacle 34 means that there may be no discharge of the pressure control fluid 26 to atmosphere, which may allow for the pressure control fluid 26 to be reused. The receptacle 34 may be provided with means for determining a volume of fluid within the receptacle 34. Such means may comprise one or more sensors (e.g. for automatic or remote operation of the apparatus 10) or visual means, such as a graduated scale showing the volume of fluid within the receptacle 34.

The pressure control arrangement 24 may be controlled by a control module. The control module may be configured to receive a signal indicative of a pressure in at least one of the flowline 14, the sample chamber 20 and the pressure control chamber 22. The control module may be configured to control the pressure control arrangement 24 to operate in accordance with one or more of the received pressure signals. The control module may be configured to monitor and control a pressure of the pressure control fluid 26 within the pressure control chamber 22, such that a rate of fluid sample flowing into the sample chamber 20 may be controlled.

The pressure control arrangement 24 may be configured for automatic operation or use from a remote location. The pressure control arrangement 24 may comprise one or more monitoring devices configured to provide an indication of performance, e.g. pump performance. The one or more monitoring devices may be configured to indicate a volume of the pressure control fluid 26 that has passed through the pressure control arrangement 24, which may indicate a position of the pressure control barrier 18 within the housing 16 and thus a volume of fluid in the sample chamber.

The pressure control barrier 18 comprises one or more sealing members 28 configured to seal against the housing 16 such that any fluid received in the sample chamber 20 is prevented from entering the pressure control chamber 22.

The apparatus 10 is connected to the flow line via a sample line 36 (e.g. a pipe branch) extending from the flowline 14. The sample chamber 20 comprises a sample inlet 38, which may be on an upper surface of the housing 16 and fluidly connected to the sample line 36 of the flowline 14. The sample inlet 38 is configured to permit fluid 12 from the flowline 14 to enter the sample chamber 20 via the sample line 36 of the flowline 14. The sample inlet 38 comprises a sample inlet valve 40. In some examples, the sample inlet valve 40 may be a non-return valve.

In this example, the pressure control barrier 18 of the apparatus 10 has been provided in an initial position within the housing 16 such that all of the housing is occupied by the pressure control chamber 22 (i.e. such that there is no sample chamber 20 present in the housing 16 initially).

Figure 2 illustrates the apparatus 10 after a first time period in which a predetermined volume of the pressure control fluid 26 has been pumped from the pressure control chamber 22 and a corresponding first volume of fluid from the flowline 14 has been received in the sample chamber 20. Figure 3 illustrates the apparatus 10 after a second time period in which a second predetermined volume of the pressure control fluid 26 has been displaced from the pressure control chamber 22 and a corresponding second volume of fluid from the flowline 14 has been received in the sample chamber 20. In other examples, the pressure control barrier 22 may be configured to move to a position after the final fluid composite sample has been obtained such that only the fluid composite sample is present in the housing.

The second time period may start a duration of time after the first time period has ended. The duration of time between receiving the first and second volumes of fluid may be in the order of seconds, minutes, hours, days, etc. In some examples, a fluid sample may be obtained every minute, e.g. over a period of 24 hours. The first and second volumes of fluid may have different properties from one another, e.g. pressure, temperature, density, viscosity, etc. When the second volume of fluid is received in the sample chamber 20, the second volume of fluid may combine with the first volume of fluid forming a composite fluid sample. Certain properties of the fluid sample may represent a function of the corresponding properties of the first and second volumes of fluid received in the sample chamber. For example, where the first and second volumes of fluid comprise the same volume, the composite fluid sample may represent an average of the properties of the first and second volumes of fluid. In other examples, however, the first and second volumes of fluid may comprise different volumes of fluid.

Figures 4 to 7 illustrate the apparatus 10 comprising a purging arrangement 42. When the apparatus 10 is initially connected to the flowline 14 via the sample line 36, there may be initial contents 44 in the sample line 36 that may need to be purged or displaced from the sample line 36 before fluid 12 from the flowline 14 is received in the sample chamber 20. In particular, the initial contents 44 of the sample line 36 may comprise one or more contaminants or pollutants (such as, air), which if not properly purged before receiving a fluid sample in the sample chamber 20 may contaminate the fluid sample and modify its composition. Thus, in order to purge the sample line 36 of its initial contents 44, fluid 12 from the flowline 14 may be allowed to enter the sample line 36 to displace (e.g. flush or purge) the initial contents 44 of the sample line. The volume of fluid for displacing the contents 44 of the sample line 36 may be equal to or more than the volume of the sample line. For example, where the sample line 36 comprises a volume of 100 millilitres, 300 millilitres of fluid 12 from the flowline 14 may be flushed through the sample line 36 to ensure all the contents 44 of the sample line 36 have been displaced before a fluid sample is received in the sample chamber.

Once the purging process has been completed, i.e. once the initial contents 44 of the sample line 36 have been fully displaced from the sample line, a fluid sample may be received in the sample chamber.

The purging arrangement 42 is configured to control a rate at which the initial contents 44 of the sample line 36 are displaced from the sample line 36 such that a pressure in the sample line 36 is maintained at or near flowline pressure as the initial contents 44 are displaced from the sample line 36 during the purging process. Fluid 12 from the flowline 14 used to displace the contents 44 of the sample line 36 that remains in the sample line 36 after the purging process has been completed will have been maintained at the same pressure as the fluid in the flowline 14. This may further improve the quality of the fluid sample received in the sample chamber, since if the fluid sample combines with any fluid remaining in the sample line 36 (after the purging process been completed) the entirety of the resulting fluid mixture should have been maintained at flowline 14 pressure throughout both the purging and sampling processes.

A flow path 46 for the initial contents 44 of the sample line 36 to travel to the purging arrangement 42 extends from the flowline 14 to the purge arrangement 42 across the sample inlet 38. A purge outlet valve 48 (e.g. a non-return valve) is provided on the sample line 36 downstream of the sample inlet. When it is desired to purge the sample line 36, the sample inlet valve 40 and the purge outlet valve 48 are opened to allow fluid to flow from the flowline 14 through the sample line 36 and displace the initial contents 44 of the sample line 36. Meanwhile, the volume of the pressure control fluid 26 in the pressure control chamber 22 may be maintained constant (e.g. with the pressure control outlet valve 32 closed) to prevent or minimise any fluid 12 from the flowline 14 entering the sample chamber 20. The purge outlet valve 48 may be configured to close after the purging operation has been completed to prevent any backflow of the initial contents 44 from the sample line 36. In some examples, the purge outlet valve 48 comprises a non-return valve.

The purging arrangement 42 may comprise a similar structure to the apparatus 10 for receiving a fluid sample described above. In particular, the purging arrangement 42 may comprise a housing 50. A pressure control barrier 52 may be movably mounted in the housing 50. A purge chamber 54 (shown in Figures 6 and 7) may be provided within the housing 50 on a first side of the pressure control barrier 52. The purge chamber 54 may be fluidly connectable to the sample line 36 for receiving the initial contents 44 of the sample line 36. A purge pressure control chamber 56 is provided in the housing 16 on an opposite second side of the pressure control barrier 52.

In this example, a purge pressure control arrangement 58 comprises a pump 60 and a pressure control valve 62 configured to operate in a similar way to the pump 30 and pressure control valve 32 described above. However, it will be appreciated that the location and number of valves 30, 32, 40, 48 may vary in practice. Similar to the purge pressure control fluid 26, a purge pressure control fluid 57 is provided in the purge pressure control chamber, which may be an incompressible fluid.

The purge pressure control arrangement 58 is configured to modify a volume of the purge pressure control fluid 57 within the purge pressure control chamber 56 to control movement of the pressure control barrier 52 to expand the volume of the purge chamber 54 and receive the initial contents 44 of the sample line 36 in the purge chamber 54. Thus, the purge pressure control arrangement 58 can control a rate at which the contents 44 of the sample line 36 are received in the purge chamber 54. This may allow the contents 44 of the sample line 36 to be received within the sample chamber 20 while maintaining the contents 44 of the sample line 36 at flowline pressure. As such, any fluid 12 from the flowline 14 used to displace the contents 44 of the sample line 36 that remains in the sample line 36 after the purging process has been completed will have been maintained at or near flowline pressure during the purging process.

The purge pressure control arrangement 58 comprises a receptacle 64. The receptacle 64 is configured to receive the purge pressure control fluid 57 displaced from the purge pressure control chamber 56. The volume of the purge pressure control fluid 57 received in the receptacle may correspond to the volume of the initial contents 44 of the sample line 36 (as well as fluid 12 from the flowline 14 used to displace the initial contents 44 of the sample line 36) received in the purge chamber 54. The receptacle 64 may be provided with means for determining a volume of fluid within the receptacle 64. Such means may comprise one or more sensors (e.g. for automatic or remote operation of the apparatus) or visual means, such as a graduated scale showing the volume of fluid within the receptacle 64. In addition, the provision of the receptacle 64 means that there may be no discharge of the purge pressure control fluid 57 to atmosphere, which may allow for the purge pressure control fluid 57 to be reused.

Figure 5 illustrates the apparatus 10 after the contents 44 of the sample line 36 (i.e., as well as fluid 12 from the flowline 14 used to displace the initial contents 44 of the sample line 36) have been received in the purge chamber 54. Figure 6 illustrates the apparatus 10 after a first time period in which a predetermined volume of the pressure control fluid 26 has been displaced from the pressure control chamber 22 and a corresponding first volume of fluid from the flowline 14 has been received in the sample chamber 20. Figure 7 illustrates the apparatus 10 after a second time period in which a second predetermined volume of the pressure control fluid 26 has been displaced from the pressure control chamber 22 and a corresponding second volume of fluid from the flowline 14 has been received in the sample chamber 20.

Figures 9 to 12 illustrate an alternative apparatus 110. The apparatus 110 comprises many of the same components as the sampling apparatus 10 described above and illustrated in Figures 4 and 7. These components have been assigned the same reference numerals as in Figures 4 and 7 incremented by 100, but have not been described again for brevity.

The alternative sampling apparatus 110 differs from the sampling apparatus 10 in that the initial position of the pressure control barrier 118 of the apparatus 110 has been provided within the housing 116 such that a major portion of the housing 116 is occupied by the pressure control chamber 22 and a minor portion of the housing 16 is occupied by the sample chamber 20. In this example, there may also be initial contents 144 in the sample chamber 120 that need to be purged or displaced before a fluid sample can be received in the same chamber 120.

The housing 116 comprises a purge outlet 149 connected to the purging arrangement 142, the purge outlet 149 being configured to allow the contents 144 of the sample line 136 and sample chamber 120 to be purged or displaced from sample line 136 and sample chamber 120, and received by the purging arrangement 142. In this example, the sample inlet 138 is provided on a side surface of the housing 116 opposite to the purge outlet 149. In this example, the flow path 146 for the contents 144 of the sample line 136 extends through (i.e. within) the sample chamber. The fluid remaining in the sample chamber 120 after the purging process been completed may be retained in the sample chamber 120 to form the first volume of the composite fluid sample.

Example locations for one or more pressure sensors P and control modules 131, 132 are shown in Figures 9-12. While pressures sensors and control modules have been omitted in the illustrations of Figures 1-8, it will be appreciated that the one or more of the pressure sensors and control modules shown in Figures 9-12 may be provided in combination with the examples shown in Figures 1-8.

Figures 10 to 12 illustrate the corresponding stages of operation of the apparatus 10 illustrated in Figures 5 to 7.

It should be understood that the examples provided herein are only presented to exemplify the present disclosure, and that various variations within the scope of the

present disclosure is possible.

Claims

CLAIMS: 1. An apparatus for obtaining a composite fluid sample from a flowline, the apparatus comprising: a housing; a pressure control barrier movably mounted in the housing a sample chamber within the housing on a first side of the pressure control barrier and being fluidly connectable to the flowline for receiving fluid from the flowline; a pressure control chamber within the housing on an opposite second side of the pressure control barrier, the pressure control chamber comprising an incompressible pressure control fluid; and a pressure control arrangement configured to control a volume of the pressure control fluid within the pressure control chamber to permit fluid from the flowline to be received in the sample chamber over multiple time periods to obtain a composite fluid sample.
2. The apparatus of claim 1, wherein the pressure control arrangement is configured to control a rate at which fluid from the flowline is received in the sample chamber.
3. The apparatus of claim 1 or 2, comprising a control module configured to control the pressure control arrangement.
4. The apparatus of any preceding claim, wherein the pressure control arrangement comprises a pump in fluid communication with the pressure control chamber.
5. The apparatus of claim 4, wherein the pump is configured to pump the pressure control fluid from the pressure control chamber to modify the volume of the pressure control fluid in the pressure control chamber.
6. The apparatus of any preceding claim, wherein the pressure control arrangement comprises a receptacle configured to receive pressure control fluid displaced from the pressure control chamber by fluid received in the sample chamber.
7. The apparatus of any preceding claim, wherein the sample chamber is connectable to a sample line of the flowline, wherein the sample line comprises initial contents to be displaced from the sample line before fluid from the flowline is received in the sample chamber.
8. The apparatus of claim 7, comprising a purging arrangement configured to control a rate at which the initial contents of the sample line are displaced from the sample line.
9. The apparatus of claim 7 or 8, wherein the purging arrangement is configured to maintain a pressure in the sample line at or near flowline pressure as the initial contents are displaced from the sample line.
10. The apparatus of claim 9, wherein a flow path for the initial contents of the sample line to travel to the purging arrangement extends from the flowline to the purging arrangement.
11. The apparatus of claim 10, wherein a portion of the flow path extends across the sample inlet.
12. The apparatus of claim 10, wherein a portion of the flow path extends through the sample chamber.
13. The apparatus of any one of claims 8 to 12, wherein the purging arrangement comprises a housing, a pressure control barrier movably mounted in the housing, a purge chamber within the housing on a first side of the pressure control barrier and being fluidly connectable to at least one of the sample line and sample chamber for receiving the initial contents of the sample line, and a purge pressure control chamber in the housing on an opposite second side of the pressure control barrier, the purge pressure control chamber comprising a purge pressure control fluid.
14. The apparatus of claim 13, comprising a purge pressure control arrangement configured to modify a volume of the purge pressure control fluid in the purge pressure control chamber.
15. The apparatus of claim 14, wherein the purge pressure control fluid comprises an incompressible fluid.
16. The apparatus of claim 14 or 15, wherein the purge pressure control arrangement comprises a receptacle configured to receive the purge pressure control fluid from the purge pressure control chamber.
17. A method for obtaining a composite fluid sample from a flowline, comprising: providing an apparatus comprising a housing, a pressure control barrier movably mounted in the housing, a sample chamber within the housing on a first side of the pressure control barrier and a pressure control chamber within the housing on an opposite second side of the pressure control barrier, the pressure control chamber comprising an incompressible pressure control fluid; fluidly connecting the sample chamber to the flowline; controlling a volume of the pressure control fluid in the pressure control chamber to permit a first discrete volume of fluid to be received in the sample chamber from the flowline; and controlling the volume of the pressure control fluid in the pressure control chamber to permit a second discrete volume of fluid to be received in the sample chamber from the flowline.
18. The method of claim 17, comprising pumping the pressure control fluid from the pressure control chamber to modify the volume of the pressure control fluid in the pressure control chamber.
19. The method of claim 17 or 18, comprising receiving the pressure control fluid from the pressure control chamber in a receptacle.
20. The method of any one of claims 17 to 19, wherein the sample chamber is connected to the flowline via a sample line, wherein the sample line comprises initial contents to be purged from the sample line before fluid from the flowline is received in the sample chamber, the method comprising, before the step of controlling a volume of the pressure control fluid in the pressure control chamber to permit a first discrete volume of fluid to be received in the sample chamber, purging the sample line.
21. The method of claim 20, wherein purging the sample line comprises allowing fluid from the flowline to enter the sample line to displace the initial contents of the sample line.
22. The method of claim 21, comprising controlling a rate at which the initial contents of the sample line are displaced from the sample line.
23. An apparatus for purging a sample line of a flowline and obtaining a fluid sample from the flowline, wherein the sample line comprises initial contents to be purged from the sample line before fluid from the flowline is sampled, the apparatus comprising: a sample chamber fluidly connectable to the sample line for receiving a fluid sample from the flowline; and a purging arrangement configured to control a pressure inside the sample line as the initial contents of the sample line are purged from the sample line.
24. The apparatus of claim 23, wherein the purging arrangement comprises: a housing; a pressure control barrier movably mounted in the housing; a purge chamber within the housing on a first side of the pressure control barrier, the purge chamber fluidly connectable to at least one of the sample line and the sample chamber for receiving the initial contents of the sample line; a purge pressure control chamber in the housing on an opposite second side of the pressure control barrier, the purge pressure control chamber comprising a purge pressure control fluid; and a purge pressure control arrangement configured to control a volume of the purge pressure control fluid within the purge pressure control chamber to control a rate at which the initial contents of the sample line are received in the purge chamber.
25. The apparatus of claim 24, wherein the purge pressure control fluid comprises an incompressible fluid.
26. The apparatus of claim 24 or 25, wherein the purge pressure control arrangement comprises a pump in fluid communication with the purge pressure control chamber.
27. The apparatus of claim 26, wherein the pump is configured to pump the purge pressure control fluid from the purge pressure control chamber to modify the volume of the purge pressure control fluid in the purge pressure control chamber.
28. The apparatus of any one of claims 24 to 27, wherein the purge pressure control arrangement comprises a receptacle configured to receive purge pressure control fluid from the purge pressure control chamber.
29. The apparatus of any one of claims 23 to 28, wherein the sample chamber is part of an apparatus according to any one of claims 1 to 7.