CN112282720A - A kind of on-site construction method of fishbone barb well and corresponding supporting equipment - Google Patents

Abstract

The application discloses an on-site construction method for a fishbone barbed well. The method includes: determining the construction point, determining the position of the seabed hydrate well, permafrost layer, and hydrate sandstone layer; According to the porosity and permeability characteristics of the reservoir and the development plan, the completion range of the fishbone spur is determined; according to the structure of the downhole operation pipe string and the completion area, the density of the fishbone spur is adjusted, the drilling direction of the branch pipe of the fishbone spur and the installation of the fishbone spur sub-section are determined. Position and number; determine the pumping pressure to ensure that the minimum pressure of the last fishbone spur joint reaches the minimum normal working pressure; turn on the pump cycle to make the last fishbone spur joint reach the minimum normal working pressure, and all the fishbone spur joints have an impact on the reservoir. Carry out fishbone barb well reconstruction; the invention utilizes ground pressure to carry out branch pipe drilling operation, with few on-site construction procedures, short time, less large-scale equipment usage, small floor space, low cost, high reconstruction density, controllable reconstruction depth, The amount of working fluid is small and the influence of in-situ stress is small; the stimulation effect of anisotropic reservoir is good.

Description

On-site construction method of fishbone well and corresponding matched equipment

Technical Field

The invention relates to the technical field of well drilling and completion, in particular to a field construction method for natural gas hydrate reservoir fishbone completion and corresponding matched equipment thereof.

Background

The natural gas hydrate is shallow in buried depth, usually located at the seabed by 0-500 m, but is generally low in abundance, distributed in a large area and locally enriched, and the well pattern density needs to be increased to improve the recovery ratio, so that the development cost is high. In the process of offshore drilling, due to factors such as complex stratum, hydrate occurrence state and the like, the problems of borehole wall collapse, drill sticking and the like are easily caused by loose reservoirs. The offshore drilling platform is limited in deck area, equipment used by measures such as hydraulic fracturing and well completion yield increase is limited, and the measures are multiple in construction links and long in operation time.

The existing fishbone drilling system can be lowered into a well only after being connected. 3-4 small-diameter drill pipes are arranged in each section of fishbone tail pipe, and the front end of each small-diameter drill pipe is connected with a jet drill bit. After the drill pipe is lowered to a preset position, a pump is started to pressurize, the small-diameter drill pipe steering guide rail extends out obliquely under the action of propelling force, and hydraulic jet operation is started to form a pore channel. However, the prior art has the following problems: (1) the fracturing construction operation needs a plurality of large fracturing pump sets, a sand mixing skid, a large amount of fracturing fluid and the like, but the offshore drilling platform has limited area and is difficult to meet the arrangement requirement of the equipment; (2) hydrate reservoirs are wide in distribution and low in abundance, so that the effective swept area of a single well is small, and the development cost is high; (3) hydrate reservoirs are complex, underground operation accidents easily occur in the drilling and completion process, the risk is high, and the operation cost is increased; (4) the hydraulic fracturing construction uses a large amount of water, proppant and chemical additives, so that environmental pollution is easily caused; (5) before hydraulic fracturing construction, operations such as well cementation, perforation, well washing and the like are needed, so that the construction period is long.

Disclosure of Invention

In order to solve the problems, the invention provides a field construction method of a natural gas hydrate fishbone well and corresponding matched equipment.

The field construction of the natural gas hydrate fishbone well comprises the following steps: determining construction points, and determining the conditions of a sea bottom hydrate well position, a frozen soil layer and a hydrate sandstone layer; determining the structure of a downhole operation tubular column according to the pressure change in the logging curve, and determining the completion range of fishbone stimulation and the performance of working fluid according to the permeability characteristics and the development scheme of reservoir holes; adjusting the fishbone density according to the structure of the underground operation pipe column and the well completion area, and determining the drilling direction of the fishbone branch pipes and the installation positions and the number of fishbone short sections; determining the pump pressure of the pump to ensure that the last fishbone short section reaches the minimum pressure for normal operation; and (4) starting the pump to circulate, so that the last fishbone short section reaches the minimum pressure of normal work, and all fishbone short sections carry out fishbone well transformation on the reservoir.

Further, the minimum normal working pressure reached at the last fishbone short section is 21MPa, namely the minimum starting pressure, and the nozzle consumes 2MPa of pressure at the moment.

Further, the manner of adjusting the density of the fishbone is as follows: the length of a single or short joint is taken as a unit, and the distance is shortened or enlarged.

Furthermore, each short section has 3-4 side branches covering a stratum section length of 12 meters, 25 fishbone joints can cover a stratum section length of 300 meters, and 100 side branches are accumulated to enter the stratum for more than 1200 m.

Further, the minimum pressure of each fishbone short section in the fishbone tool string is 21MPa when the fishbone short section works normally.

Further, the range of the fishbone completion is determined to be 300-500 m section stratum according to the reservoir hole permeability characteristics and the development scheme.

The field construction corollary equipment of the invention includes: the device comprises a mud pump, a pulping pool, an injection fluid, a fishbone branch pipe, a main pipe, a hanger, a tail pipe string, a feeding pipe column and a casing pipe.

Further, fishbone completion pipe string includes a plurality of fishbone branch pipe nipples, and every fishbone branch pipe nipple includes and keeps off sand medium, outer safety cover, check valve and fishbone branch pipe, and wherein, keep off sand medium and install on the outer wall of fishbone branch pipe nipple, and outer safety cover is installed on the outer wall that keeps off sand medium, and fishbone branch pipe nipple, keep off sand medium, outer safety cover and fishbone branch pipe are the tubulose.

Furthermore, the main pipe is matched with the size of the well hole and comprises a centralizer, and holes are formed in the designated positions of the outer wall of the branch pipes and used for the branch pipes to drill.

Furthermore, according to the corresponding size and the number of the ground preparation, the fishbone branch pipes are put into the ground together with the main pipe and are suspended in the upper casing.

The field construction method of the fishbone well and the corresponding matched equipment provided by the invention have the following beneficial effects: the on-site construction method of the fishbone well utilizes ground pressurization to carry out drilling operation, and the on-site construction time is less than 0.5 day; the working procedures are reduced, the operation cost can be greatly reduced, and the economic index is improved. Compared with the conventional operation aggregate of the operation links such as casing running, well cementation, plug drilling, perforation, pipe scraping, well completion and yield increase and the like of the horizontal well, the invention can moderately relax the harsh condition with high quality requirement of the horizontal well cementing, has a plurality of advantages compared with the conventional hydraulic fracturing yield increase mode, does not need a fracturing pump group, has small floor area and requires less liquid amount for the yield increase operation compared with the same condition; the quantity of the pump and the tank is less than that of the pumps and the tanks for fracturing and acid fracturing; the depth of the ground entering is less than 12m, the range is adjustable, and the penetration depth of the ground can be controlled; the lower packer is selected according to the stratigraphic layering requirement, and the requirement of the required layering section can be met.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art according to the drawings.

FIG. 1 is a flow chart of a method for constructing a fishbone well in situ according to an embodiment of the invention;

fig. 2 is a block diagram of a fish bone completion string according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present application are clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Furthermore, the following description of the various embodiments refers to the accompanying drawings, which illustrate specific embodiments in which the invention may be practiced. Directional phrases used in this disclosure, such as "upper", "lower", "front", "rear", "left", "right", "inner", "outer", "side", and the like, refer only to the orientation of the appended drawings and, therefore, are used in a better and clearer sense to describe and understand the present invention, and are not intended to indicate or imply that the referenced device or element must be in a particular orientation, be constructed and operated in a particular orientation, and is not to be considered limiting of the present invention.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted", "connected" and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; may be a mechanical connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The invention aims to provide a field construction method of a fishbone well, which solves the problems in the prior art and has the characteristics of good yield increasing effect, simple construction, short construction period, low cost and the like.

In order to make the above objects, features and advantages of the present invention more apparent and understandable, a method for constructing a fishbone well according to the present invention in situ is described in detail with reference to fig. 1.

The field construction method of the fishbone well comprises the following steps:

s101: determining a construction site, a sea bottom hydrate well position, a frozen soil layer and a hydrate sandstone layer;

firstly, determining a construction sea area, preliminarily decomposing data such as water depth, hydrate reservoir type, burial depth and the like, and determining a sea bottom hydrate well position, a frozen soil layer and a hydrate sandstone layer.

S102: determining the downhole structure of the operation pipe column according to a pressure change curve in a logging curve, and determining the completion range of fishbone and the performance of working fluid according to the permeability characteristics and the development scheme of a reservoir hole;

secondly, determining the structure of the downhole operation string according to the formation pressure change in the logging curve, and further performing 300-500-meter formation coverage in a well completion area according to the permeability characteristics of a reservoir hole and a development scheme.

The 4 side branches of each joint provided by the invention cover the length of a stratum section of 12 meters, 25 fishbone joints can cover a stratum section of 300 meters, and 100 side branches are accumulated to enter the stratum for more than 1200 m.

S103: adjusting the density of fishbone, and determining the drilling direction, the installation position and the number of the fishbone branch pipes by taking the length of the short section as a unit;

and adjusting the fishbone density according to the structure of the underground operation pipe column and the well completion area, shortening or enlarging the distance by taking the length of a single or short section as a unit, and determining the drilling direction of the fishbone spur branch pipes and the installation position and number of the fishbone spur short sections.

S104: determining the pump pressure of the pump to ensure that the last fishbone branch pipe joint reaches the minimum normal working pressure of 21 MPa;

determining the pump pressure to be pumped according to the drilling direction of the fishbone branch pipes and the installation positions and the number of the fishbone short sections, so as to ensure that the pipe joint of the last fishbone branch pipe reaches the minimum normal working pressure, wherein the minimum normal working pressure is 21 MPa; the nozzle consumes 2 MPa.

S105: starting a pump for circulation, so that the last fishbone short section reaches the minimum normal working pressure of 21MPa, and carrying out fishbone well transformation on the reservoir by all fishbone short sections;

and after the fishbone completion penetration is put in, the pump is started to circulate, and after the last fishbone short section reaches the normal working minimum pressure of 21MPa, all fishbone short sections carry out fishbone well reconstruction on the reservoir.

In the invention, the field construction corollary equipment required to be provided comprises: the device comprises a mud pump, a slurrying pool, a jet fluid, a fishbone completion pipe string, a main pipe, a hanger, a tail pipe string, a feeding pipe string and a casing pipe.

Referring to fig. 2, a fishbone completion string used in the field construction kit according to the present invention will be described in detail.

As shown in fig. 2, fishbone completion pipe string comprises a plurality of fishbone branch pipe nipples (1), fishbone branch pipe nipples (1) contain sand blocking medium (2), outer protective cover (3), check valve (4) and fishbone branch pipe (5), sand blocking medium (2) are installed on the outer wall of fishbone branch pipe nipples (1), outer protective cover (3) are installed on the outer wall of sand blocking medium (2), fishbone branch pipe nipples (1), sand blocking medium (2), outer protective cover (3) and fishbone branch pipe (5) are tubiform.

The main pipe used by the on-site construction matching equipment is matched with a borehole and comprises a centralizer, a float collar, a float shoe and other tools, and a hole is formed in an appointed position for a branch pipe to drill.

In order to match the fishbone completion pipe string, the invention also needs to use a running tool, connect buckle type confirmation, buckle changing processing and pipe column upper shackle, and prepare corresponding size and quantity according to stratum, the fishbone branch pipes are run into the stratum along with the main pipe and are suspended in an upper casing pipe.

The slurry making tank used in the invention is used for preparing the branch pipe drilling fluid by adding corresponding abrasive or acid liquor according to the stratum property so as to facilitate the completion and pressurized drilling of fishbone. Meanwhile, in order to meet the requirements of site construction, construction labor protection supplies are required to be provided; and meanwhile, a field service engineer is arranged on a construction site.

The present invention will be described in further detail with reference to specific examples.

Example 1:

1) the North America XX oil field #2 well, the stratum of production is texas chalk series limestone with the highest stratum hardness in the world, belong to low pressure crude oil production well, 15 fishbone joints are put into operation, the construction displacement is 8.1 barrels per minute, about 2000 barrels of acid liquor are squeezed into the stratum, 4 hours of squeezing, and the highest construction pump pressure is limited to 3250 Psi.

2) Application conditions of fishbone;

an open hole wellbore; borehole size: 8-1/2 ' or 6 ' -6-1/2 '; the normal working pressure of the tool is 21MPa, and the pressure resistance is 35 MPa; conventional tool formation downhole temperatures do not exceed 175 ℃; the method is suitable for vertical wells, inclined wells, directional wells or horizontal wells; setting a casing pipe with the same size as the casing pipe with the same size to the dog leg degree of the shaft; the horizontal well can give consideration to upper and lower layer multi-layer comprehensive exploitation; the depth of the fishbone needle tube entering the ground is 12 meters; the pore-forming density is not more than 4 (or 3)/12 m; all fishbone needles need to enter the formation simultaneously.

3) Giving a construction design scheme by an engineer;

4) according to the design scheme, workers work on the construction site;

assembling a field operation tool, putting the fishbone tool into a well, and pumping acid.

5) And field construction working parameters:

pressure of the last section of fishbone: 21MPa

Nozzle consumption pressure: 2MPa of

Coverage range: 300-500 m

The well fluid loss rate: 6 barrels per minute

Liquid level depth before operation: 5200-

Acid liquor injection mode: squeeze-in (below formation fracture pressure)

Acid liquor name: 15% HCL + preservative + additive

Acid squeezing operation time: 5: 38- -8: 38, replacing liquid: 8: 38- -8: 58, 3: 20 in total

Acid squeezing discharge capacity: 8.1 barrels per minute, maximum working displacement: 10 barrels per minute (for liquid)

Amount of acid squeezed in: 1915 barrels, total injection liquid volume: 2058 barrel

Highest ground pump pressure: 3250psi, lowest surface pump pressure: 100psi

Intermediate pressure rise time: 6: 52 (corresponding to the forward operation time of the needle tube for 74 minutes)

The amount of acid liquor consumed by all needle tubes entering the formation is as follows: 599.4 bucket (95.3 square)

Acid liquor excess allowance coefficient: 3.2

6) Matters of attention

Construction attention: the hanger and the top packer seat are matched with the fishbone tool;

attention to the tool: when the pipe column is lowered in an open hole, the guide shoe needs to have a reaming function, when the pipe column is blocked, a pump is not started to circulate slurry as much as possible, and the pipe column is preferably lifted and lowered or rotated to lower the drill.

7) Results

The fishbone can be safely implemented underground, and the operation risk is within an acceptable range; the tail pipe can be safely lowered to the bottom of the well by rotating in the process of lowering the pipe column into the well; a 12-meter needle tube is read on the pressure diagram to completely enter the stratum, and the normal work of the forward pulser is verified; confirming successful seating of the ossicular anchor; closing the acid liquor circulating valve according to a preset scheme; successfully predicting the penetration rate and the construction pumping liquid amount required by field operation through an indoor test; 30 sets of positive pulse valves were used.

The field construction equipment of the fishbone tube well can simply, accurately and efficiently communicate the oil reservoir; in the operation, a 4.5-inch pipe column is used for connecting 15 fishbone tail pipes, and 3 open hole reverse thrust anchors are installed; so that the pump-on operation can be smoothly performed according to the plan. Closing the circulating valve after meeting acid, starting the spraying operation, and successfully opening 60 branches; the whole operation is smoothly finished according to the original plan; when the fishbone needle tube is completely released, the pressure gauge displays back pressure; the entire pumping operation lasts for about 5 hours, including spraying operation and liquid back-flow.

The difficulty and significance of the invention in solving the problems of the prior art are as follows: (1) the natural gas hydrate mainly contains methane, is a green energy source, is listed as the 173 th mineral species in China, can generate at most 164 unit volumes of natural gas under the standard condition when decomposed in unit volume, and has a great amount of natural gas hydrate in the deep sea of the south sea of China, thereby having great significance for relieving the total energy demand of China. (2) The fishbone completion reservoir reconstruction effectiveness is high. The main well hole can effectively increase the exposed area of a hydrate reservoir through a plurality of branch pipes, so that the yield of natural gas is improved, and the trend and the length of the branch pipes can be adjusted according to the characteristics and the requirements of the reservoir. (3) The fishbone completion construction process is simple. The liner string is conventional and is provided with liner hanger slips. The production increasing operation is completed while well completion, and operations such as well cementation, perforation, well washing, fracturing and the like are not needed. (4) The fishbone completion can reduce the operation cost. Compared with the conventional reservoir transformation operation which has the advantages of multiple operation flows, long operation time, multiple ground large-scale equipment and complex working procedures, the fishbone completion utilizes ground pressurization to carry out drilling operation, the field construction time is less than 0.5 day, a plurality of fracturing pump sets are not needed, the occupied area is small, the operation flow is simple, and the operation cost can be greatly reduced. (5) The fishbone completion well effectively protects the reservoir. In the process of increasing production by hydraulic fracturing, the reservoir is easily damaged, and the fishbone completion technology can effectively protect the reservoir. (6) The fishbone completion has little impact on the environment. Through reducing operation flow and engineering time, the operation water consumption is little, has reduced the influence to the environment, has avoided the flowback and the processing of traditional hydraulic fracturing fluid simultaneously.

While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application. It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (10)

1. A field construction method of a fishbone well comprises the following steps:

determining construction points, and determining the conditions of a sea bottom hydrate well position, a frozen soil layer and a hydrate sandstone layer;

determining the structure of a downhole operation tubular column according to the pressure change in the logging curve, and determining the completion range of fishbone stimulation and the performance of working fluid according to the permeability characteristics and the development scheme of reservoir holes;

adjusting the fishbone density according to the structure of the underground operation pipe column and the well completion area, and determining the drilling direction of the fishbone branch pipes and the installation positions and the number of fishbone short sections;

determining the pump pressure of the pump to ensure that the last fishbone short section reaches the minimum pressure for normal operation;

and (4) starting the pump to circulate, so that the last fishbone short section reaches the minimum pressure of normal work, and all fishbone short sections carry out fishbone well transformation on the reservoir.

2. The site operation method of claim 1, wherein the minimum normal working pressure reached at the last fishbone nipple is 21MPa, the minimum starting pressure, and the nozzle consumes 2 MPa.

3. The site construction method according to claim 1, wherein the manner of adjusting the density of the fishbone is: the length of a single or short joint is taken as a unit, and the distance is shortened or enlarged.

4. The site construction method of claim 3, wherein each short section has 3-4 lateral branches covering a formation section length of 12 meters, 25 fishbone joints can cover a formation section length of 300 meters, and 100 lateral branches are accumulated to enter the formation for more than 1200 m.

5. The field construction method of claim 3, wherein each fishbone nipple in the string of fishbone tools has a minimum pressure of 21MPa during normal operation.

6. The in-situ construction method as claimed in claim 1, wherein the range of the fishbone completion is 300-500 m sections of stratum according to the reservoir pore permeability characteristics and the development scheme.

7. An on-site construction kit to be applied to the on-site construction method according to claim 1, wherein the on-site construction kit comprises: the device comprises a mud pump, a pulping pool, an injection fluid, a fishbone branch pipe, a main pipe, a hanger, a tail pipe string, a feeding pipe column and a casing pipe.

8. The field construction kit of claim 7, wherein the fishbone completion string comprises a plurality of fishbone branch subs, each fishbone branch sub comprising a sand-blocking medium, an outer protective cover, a check valve, and a fishbone branch pipe, wherein the sand-blocking medium is mounted on an outer wall of the fishbone branch sub, the outer protective cover is mounted on an outer wall of the sand-blocking medium, and the fishbone branch subs, the sand-blocking medium, the outer protective cover, and the fishbone branch pipe are all tubular.

9. The field construction kit of claim 8, wherein the main pipe is sized to fit the borehole and comprises a centralizer, a float collar, a float shoe, and a hanging tool, and the lateral pipe has a hole at a predetermined position on its outer wall for drilling.

10. The kit for construction in situ according to claim 9, wherein the branched fishbone pipes are prepared in corresponding sizes and numbers according to the ground, and are lowered into the ground together with the main pipe and suspended in the upper casing.

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