RU2636843C1 - Method for taking deep samples of formation oil in well when testing and coupling for directing flow of formation fluid for its implementation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in order to implement the method, a tubing string equipped with a mounting nipple for installation of sampling equipment and the coupling for directing the flow of formation fluid at the tubing bottom are lowered into the well. After depression is created, the evaluation of inflow rate and presence of oil in the inflow is carried out. The time required for oil to fill the tubing below the nipple is calculated by the inflow rate, and the operation time of the sampler is determined. The method includes running equipment consisting of a mandrel for hermetic seating into the seat nipple on the tubing of shut-off valve together with the sampler and a deep self-contained thermomanometre. Air-tight fitting of equipment into the seat nipple is performed, thus shutting-off the tubing string by the plug-in equipment. This creates conditions for accumulation and selection of depth sample of formation oil in the well in close proximity to the formation top. The formation oil is directed through the coupling for directing the flow in drop-jet form at low depression into the tubing string space, the sample is separated and accumulated in the rated period under the shut-off valve and the deep sample of the formation oil is taken out by the sampler installed together with the shut-off valve.

EFFECT: providing sampling of representative samples of formation oil, the application of which is possible at non-flowing test facilities.

2 cl, 3 dwg, 1 tbl

Description

The invention relates to the field of oil and gas industry and is intended for the selection of deep samples of reservoir oil when testing wells in a production casing for all oil inflows, including formation water.

Existing methods for deep reservoir oil sampling traditionally determine the method for producing reservoir oil only in flowing, working or stopped oil wells with an electric centrifugal pump (mainly without inflow of produced water).

Known methods for taking in-depth fluid samples in a production string using sampler configurations with all kinds of shutoff valves (shutoffs, shutoff valves) of the tubing tubing in a layout with a packer covering the annulus (between the tubing and production string).

A known method of sampling deep samples of reservoir fluid, in which the sampling of deep samples is carried out by samplers, passed on a wire (cable) through a device for blocking the axial channel of the pipe lift string with the shutter opening (RU No. 2203391, publ. 04/27/2003).

A known method of sampling deep samples of reservoir fluid, in which the sampling of deep samples is carried out by samplers, lowered on a wire (cable) through a direct-flow borehole valve-cutter of the axial channel of the pipe lift string with their automatic cut-off below the cutoff valve (RU No. 2564701, publ. 10.10.2015 )

There is a method of sampling in-depth samples using a device for hydrodynamic monitoring of wells (RU No. 2471984, published January 10, 2013) in a depressed mode, namely, to tightly shut off an internal cavity of a tubing string to record a pressure recovery curve (HPC) of a formation using remote geophysical instruments for the rapid determination of hydrodynamic parameters of the reservoir and sampling of the reservoir fluid.

There is a method of taking deep samples of reservoir fluid using a device for hydrodynamic research and testing of wells in a depressed mode, namely, for tightly shutting off the internal cavity of a pipe string (tubing) to record a pressure recovery curve (HPC) of a formation using remote downhole tools for operational determination of the hydrodynamic parameters of the investigated formation. (RU No. 2584169, publ. 05.20.2015), in which the sampler is suspended below the device. Sampling is carried out after overlapping the internal cavity of the tubing during registration of the HPC. In this case, the annulus of the tubing is blocked by the packer.

A known method of LLC Weatherford, the deep sampling fluid in non-flowing wells, in the production string using a programmable for opening and closing the shut-off valve (ESIT) in the layout with a sampler (EPST) and a depth gauge, lowered with a mandrel into the landing nipple of the pump-pump assembly compressor pipes (tubing) installed using a packer in the position of the overlap of the annulus. A deep oil sample can be taken by timer both during the inflow into the tubing and during the recording period of the HPC (the pipe cavity is blocked by a shutoff valve). Schlumberger has the same equipment and method for taking a deep sample.

Common disadvantages of these known methods are:

- the lack of methods for preserving oil in the well in reservoir conditions on non-flowing tributaries at a pressure at the selection point above the saturation pressure. Oil entering the well prior to closing the well for registration of the HPC may be degassed;

- at the point of oil extraction, below the device for blocking the axial channel of the tubing, oil can accumulate only when it enters the pipe cavity before the shut-off valve closes. Its quantity is not enough to obtain a high-quality anhydrous sample, due to the cessation of oil flow from the reservoir with a closed device for blocking the axial channel of the tubing, and with the annulus blocked by the packer.

There is a well-known generally accepted method for taking deep samples of reservoir oil on gushing tributaries, according to regulatory documents (OST 153-39.2-048-2003 “Oil. Typical study of reservoir fluids and separated oils”, STO RMNTK 153-39.2-002-2003 “Oil. The selection of reservoir fluids "). The method also has a number of limitations when flowing, if:

- bottomhole pressure on the roof of the reservoir below the saturation pressure; bottomhole pressure on the oil-water circuit in the wellbore

below saturation pressure (for oil-water flowing objects);

- bottomhole pressure on the oil-water circuit in the wellbore below the saturation pressure (for oil low-flowing flowing objects with an unrecoverable balance of process water);

- deposition of paraffins and resins on the walls of the tubing during well testing, hence, not the passage of samplers along the tubing.

The present invention is aimed at solving these problems by providing the conditions for the gas in the dissolved state in the oil to cause an inflow. Using the proposed method for taking a deep sample of reservoir oil, there is no need to bring the well into the flowing mode for taking deep samples.

The objective of the invention is to develop a method for taking deep samples of reservoir oil at non-flowing objects of testing and testing of formations, in which the phase state of deep samples of oil corresponds to the state of reservoir oil.

The technical result of the invention is expressed in ensuring the selection of representative samples of reservoir oil, the use of which is possible at non-flowing test objects.

The specified technical result is achieved by the fact that for the implementation of the method of taking deep samples of reservoir oil during testing, the assembly of tubing pipes (hereinafter tubing) equipped with a landing nipple for installing equipment for sampling (20-30 m to the bottom of the tubing) is lowered into the well, and a reservoir fluid flow direction clutch at the bottom of the tubing. The flow direction coupling is located 20-30 m before the formation roof.

They create a depression on the formation by swabbing or compression without putting the well into the flowing mode, providing conditions at the point of accumulation and sampling of oil under which the pressure at the point of taking a deep sample is more than the pressure of saturation of the formation oil with gas, but less than the reservoir pressure.

After creating a depression, an assessment is made of the flow rate of the inflow and the presence of oil in the inflow. The flow rate calculates the time required to fill the tubing with oil below the equipment for sampling and the response time of the sampler.

The descent of sampling equipment is carried out, consisting of a mandrel for a tight fit into the landing nipple on the tubing of the shut-off valve (shut-off valve in the "closed" position) complete with a sampler and a deep autonomous thermomanometer. Airtight installation of equipment is carried out in the landing nipple, thus blocking the tubing trunk with plug-in equipment. This creates the conditions for the accumulation and selection of a deep sample of reservoir oil in the well in the immediate vicinity of the formation roof.

The specified technical result is achieved in that the coupling of the direction of flow of the reservoir fluid contains a receiving funnel, a tubular housing, a tubular element located inside the housing with the formation of the Central and annular channels.

The receiving funnel of the coupling is connected to the lower end of the housing and has the maximum allowable outer dimension to overlap the cavity of the production string.

The inner tube element is hermetically connected in the lower part to the casing; it has openings in the upper part through which it communicates through the annular channel with the pipe casing.

The tube body contains in its lower part openings through which it communicates with the annulus.

Through a flow direction coupling connected to the annular space through a system of central and annular channels above the place where the formation fluid flow into the coupling is received, oil in the drip-jet form is separated with small depression and sent to the cavity of the tubing to the sampler under a closed shut-off valve. The separation and accumulation of oil is ensured by a high speed of oil rise at a relatively low speed of flow through the flow direction coupling, as well as by changing the direction of flow down in the annular channel of the coupling connected to the annulus.

The ascent rate of oil in water is several times higher than the velocity of formation fluid flow inside the production casing with non-flowing inflow.

The change in the direction of flow of the reservoir fluid in the flow direction coupling occurs when it moves from the reservoir through a receiving funnel to the central (inner) channel, then through the upper holes of the internal pipe channel into the annular channel to the lower part of the housing and then through the holes in the lower part of the housing into the annular space.

The reservoir oil in the tubing under the shutoff valve is accumulated in the calculation period, which depends on the flow rate of the inflow.

After that, a deep sample of reservoir oil is sampled with a sampler, which is triggered by a timer or by remote control from the surface after the estimated time of oil accumulation.

At the moment of operation of the sampler, the pressure and temperature are recorded by a deep autonomous thermomanometer installed together with the sampler. After sampling, the shut-off valve with the sampler and the depth thermomanometer is removed to the surface and the quality of the depth sample of the reservoir oil is evaluated. According to the result, repeat the selection of the required number of samples or, if necessary, adjust the accumulation program and re-take in-depth samples.

The proposed method for taking in-depth samples of reservoir oil is based on creating in the wellbore the conditions for oil flow from the reservoir at a pressure above the saturation pressure, accumulating it in the tubing under these conditions, and taking in-depth samplers.

The method is based on the fact that no gushing tributaries condition where the bottomhole pressure is greater than the saturation pressure (P _H> P _N) can be stored in a range of small depressions on the bottom in a particular range of depths.

If you create conditions for the accumulation of jet-drop oil coming from the reservoir through the column of borehole technical water to the sampling point that meets the condition (P _S > P _N ) and take a deep sample from this point, then the obtained deep oil sample will be corresponding in phase state reservoir (gas in a dissolved state in oil).

Accurate knowledge of the properties of reservoir oil (reservoir viscosity, density, gas content) is very important at all stages of the implementation of oil production projects - from the development design to the completion of production at the field.

Up to 70% of test objects in oil-saturated formations are not gushing objects. Conventional test methods and hydrodynamic studies at such facilities consist of recording a level recovery curve in the well and recording a pressure recovery curve. In-depth sampling is not done.

At low flow rates, oil enters the well from the reservoir in a droplet form and is collected at the liquid level (water or solution) in the well. In world test practice, there is the problem of obtaining (sampling) deep oil samples at such non-flowing objects, because when moving to the surface through the borehole fluid (water, solution), the oil is in the droplet form, and at the level it is collected in a degassed form.

The method is illustrated by the following drawings, where in FIG. Figure 1 shows the flow chart of oil after a depression has been created with a tubing assembly with a shut-off valve, a sampler, and a pressure gauge that are not installed in the nipple.

In FIG. Figure 2 shows a diagram of oil intake and accumulation below a closed shut-off valve that covers the tubing cavity after installing a mandrel with equipment for accumulating and sampling deep oil samples into a nipple.

In FIG. 3 shows a design diagram of a formation fluid flow direction coupling.

The proposed method is as follows.

The process is carried out in two stages.

The first stage: the call of the influx.

The bottom of the tubing 1 is equipped with a coupling 2 directions of flow. The tubing 1 is run down with the landing nipple 3 installed above the coupling 2 of the flow direction at 20-30 m, to a depth of 20-30 m from the roof of the formation. A non-gushing inflow is called by swabbing or compression during depressions that ensure the preservation of the phase state of oil saturated with gas at the point of planned deep sampling. The magnitude of the depression to cause the inflow is determined from the condition: the pressure at the sampling point is greater than the pressure of saturation of the oil with gas (Pt.train> Pn.).

The flow rate in the well is estimated: according to the standard record of the level recovery curve (CLC) by a deep gauge (according to the increase in bottomhole pressure for a certain period, and according to the internal volume of the production string in the interval of the increase in fluid level), the flow rate of the well is determined, a fluid sample is taken from its level to well and determine the presence of oil in the influx.

Calculate the time required to fill the tubing (pipes) with oil below the shutoff valve 4 for taking a depth sample according to the formula:

Tn = V⋅H / Q / 1000⋅24⋅k,

where Tn is the time of oil accumulation under the shutoff valve, hours;

V - internal volume of 1 linear meter of tubing in the interval from the shutoff valve to the guide sleeve, liter;

N - the height of the column of reservoir oil, necessary for the selection of high-quality depth samples (10-20 m), m

Q - flow rate, m ³ / day;

k - reserve coefficient, taking into account the proportion of oil from the entire flow entering the tubing cavity, is assumed to be 5 (20% of the total flow). The value is subject to testing in practice and adjustment.

1000 and 24 - conversion rates of flow rate in liter / hour.

Oil under depression evenly floats in the form of a droplet-liquid along the pipe and annular space, because the cross-sectional area of the receiving funnel of the coupling 2 and the annular space of the funnel-production tower are approximately equal.

Create the conditions for the accumulation of oil at the point of taking a deep sample by running on a wireline (scraper wire) 5 equipment for taking a deep sample (programmed shutoff valve 4 in the closed position, tightly connected to mandrel 6, with a sampler 7 and a depth thermomanometer 8). Overlap the tubing trunk 1 at a depth of landing mandrel 6 in the landing nipple 3.

The accumulation of oil is ensured by the high rate of oil ascent along the tubing 1 to the sampler 7 when passing through the sleeve 2 of the flow direction, with access to the annulus.

In addition, the guaranteed separation and direction of oil to the accumulation place under the shut-off valve 4 (Fig. 2) provides the design of the coupling 2 of the flow direction (see Fig. 3).

The reservoir fluid flow direction coupling 2 comprises a housing 9 communicating in the lower part through the holes 10 with the annulus, an inner pipe element 11 sealed in the lower part with the housing 9 and communicating through the holes 12 in the upper part with the housing 9, with the formation of a central and ring channels. A receiving funnel 13 is screwed onto the body 9, having the maximum permissible outer dimension to overlap the cavity of the production string, serves to direct the flow of formation fluid into the cavity of the flow direction coupling.

The coupling 2 of the direction of flow of the reservoir fluid works as follows.

The flow of formation fluid from the reservoir (oil or oil with produced water) enters the production casing, then, when moving along the production casing, it is divided into a stream entering the receiving funnel 13 and a stream entering the annulus approximately in equal volumes (with equal areas sections at the entrance to the funnel and the annular space between the receiving funnel 13 and the production string).

The flow of fluid from the reservoir into the sleeve 2 when the tubing 1 cavity is blocked by the shutoff valve 4 is provided by a system of channels and circulation holes from the inner cavity of the sleeve 2 into the annulus.

The flow of formation fluid from the receiving funnel 13 enters the central (inner) channel, then through the upper holes 12 of the inner pipe element 11 into the annular channel into the lower part of the housing 9 and then through the holes 10 in the lower part of the housing 9 into the annulus. When the flow of formation fluid from the Central channel into the holes 12 of the inner pipe element 10 in the lower part of the annular channel, the oil from the stream due to the buoyancy forces of the medium (water with a higher density) is separated and floats into the tubing cavity 1.

Separation from the flow of formation fluid and the accumulation of oil is ensured by a high rate of oil emergence along the tubing 1 to the sampler 7 when passing through the sleeve 2 of the flow direction (Fig. 2), with access to the annulus.

When the flow passes through the coupling 2 due to the multiple excess of the oil ascent rate over the flow rate and the technical device of the flow direction coupling 2, the formation oil is separated and accumulated under the shutoff valve 4 in the calculation period,

When oil passes through the flow direction clutch 2 at the entrance to the circulation openings due to gravitational forces, oil floats to the shutoff valve 4 (see Fig. 2), since the oil ascent rate (350 m / h) is an order of magnitude higher than the flow velocity fluid from the reservoir along the production string.

For example, table 1 shows the flow velocity of the reservoir fluid in the production casing at various flow rates, calculated without taking into account the influence of gravitational ascent of oil in water. The calculation was performed in the flow rate range of non-flowing tributaries.

Second stage: taking a deep sample.

Depth sampling at the point of oil accumulation below the shutoff valve 4 by the programmable sampler 7 occurs after a certain (estimated) time according to a timer with fixing the bottomhole pressure and temperature at this point with a thermomanometer 8.

The lifting of the shutoff valve 4 is carried out together with the deep sampler 7 to the surface, and the quality of the deep sample of reservoir oil is evaluated by discharge.

Next, all the operations for lowering the plug-in equipment are repeated in order to select the required volume of deep samples (as a rule, at least 3).

The advantages of using the proposed method for sampling reservoir oil:

- there is no need at the oil facility to bring the well into gushing mode;

- deep sampling is possible upon receipt of a mixed inflow: oil + produced water, produced water with a film of oil;

- improving the quality (conditionality) of the selected in-depth samples (reducing rejects from 33% to 10% for facilities with gushing flow);

- when using a packer in the tubing arrangement, after taking in-depth samples, it is possible to combine work with testing and hydrodynamic studies (HLV + HLR). Note: Packer is not used for sampling.

The effectiveness of the introduction of new technology is as follows:

- deep oil sampling at non-gushing oil facilities with a flow rate of up to 2 m3 / day, up to 100% of facilities, including TRIZ;

- deep oil sampling at non-gushing oil and water facilities with an oil flow rate of up to 2 m3 / day, up to 100% of the facilities;

- deep oil sampling at potentially gushing oil facilities, including with produced water up to 50% of objects;

- improving the quality of in-depth samples up to 90%.

An increase in the supply of deep-seated oil facilities to 60% (taking into account the quality of the samples - 90%) will lead to an increase in the quality of development projects for predicting well flow rates by detailing the oil viscosity and gas content data on the area of the deposit.

Claims (2)

1. A method of taking deep samples of reservoir oil during well testing, including lowering the assembly of tubing with a fitting nipple into the well for installing sampling equipment, creating depression on the reservoir, lowering the equipment for taking deep oil samples, performing deep oil sampling with registration pressure and temperature in the inflow mode, characterized in that the bottom of the string of tubing before lowering is additionally equipped with a sleeve for the direction of flow of formation fluid into the tubing pipes, create depression without putting the well into flowing mode, evaluate the flow rate and the presence of oil in the flow, calculate the time required to fill the tubing with oil below the nipple and the response time of the sampler, lower the equipment consisting of a shut-off valve on the mandrel to close the channel of the tubing with equipment for the selection of deep samples of reservoir oil, consisting of a sampler and deep autonomous thermomanometer, carry out a tight installation of a mandrel in the landing nipple, block the tubing stem below the nipple, which ensures formation oil accumulation conditions at the sampling point, at which the pressure at the depth sampling point is greater than the saturated oil pressure of the formation gas with gas, but less than reservoir pressure, while the formation oil they are directed through the flow direction sleeve in the drip-jet form with a small depression into the cavity of the tubing, are separated and accumulated in the calculation period under the shut-off valve, then sampling a deep oil sample of a reservoir oil with a sampler installed together with a shut-off valve and working through the estimated oil accumulation time, an autonomous depth thermomanometer records the pressure and temperature at the moment the sampler is triggered, then remove the shut-off valve complete with a sampler and a deep thermomanometer to the surface and evaluate quality of a deep reservoir oil sample; re-sampling of deep reservoir oil samples is performed. 2. The reservoir fluid flow direction clutch comprising a receiving funnel, a tubular body, a tubular element located inside the housing to form a central and annular channels, the receiving funnel of the coupling connected to the lower end of the tubular housing and has a maximum allowable outer dimension to overlap the cavity of the production string, the inner tube element is hermetically connected in the lower part to the casing and has openings in the upper part through which it communicates through the annular channel with the pipe casing orpus comprises in its lower part, openings through which it communicates with the annulus.

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