A process string for micro-injection testing and related methods

Abstract

This invention discloses a perforation micro-injection pressure measurement string and method for shale oil and gas wells. The string includes: coiled tubing, an anchoring tool and packer assembly, a quantitative shut-off valve, a centralizer, a pressure-controlled opening valve, a perforation gun, and a guide shoe, all threaded together in sequence. The switches for the quantitative shut-off valve and the pressure-controlled opening valve are located on the side. The quantitative shut-off valve provides a circulation channel for the string. Before the pressure-controlled opening valve opens, the quantitative shut-off valve is closed, preventing fluid circulation inside and outside the string. This increases the pressure to set the packer and open the pressure-controlled opening valve, sealing the annulus. Fluid is then injected outwards through the channel opened by the pressure-controlled opening valve. Compared to traditional micro-injection testing, this string reduces the impact of wellbore reservoir effects and improves the accuracy of pressure measurement data.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development, and specifically relates to a process string and related methods for micro-injection testing. Background Technology

[0002] Shale oil and gas has extremely low permeability and a complex and variable pore structure. Shale oil and gas reservoirs are characterized by ultra-low permeability, resulting in extremely weak fluid flow and making it difficult to form quasi-radial flow. Therefore, it is very difficult to obtain parameters such as original formation pressure and permeability using traditional pressure recovery testing methods. The emergence of micro-injection testing technology has provided a new approach for interpreting and evaluating formation parameters and far-well fracture parameters.

[0003] Micro-injection testing technology can be used to identify gas well flow patterns through pressure drop test data, and a set of pressure drop data interpretation methods can be obtained to predict fracture propagation and formation parameters. The basis of this interpretation is formation pressure data, and accurate acquisition of formation pressure data is crucial.

[0004] However, shale oil development often employs horizontal wells with long horizontal sections and large wellbore volumes. In low-permeability reservoirs, prolonged wellbore storage is common, particularly in poorly permeable, low-production, low-pressure, shut-in, and deep gas-producing wells. In these wells, the wellbore storage phase often lasts for several logarithmic cycles, and the large wellbore storage coefficient causes late or absent formation radial flow during the testing period. Furthermore, different wellbore effects often exhibit similar characteristics in the early stages of well testing curves, or the wellbore effect and formation response show consistent characteristics in early well testing curves, exacerbating the ambiguity in well test interpretation and severely impacting subsequent data interpretation.

[0005] Therefore, in response to the above problems, according to the previous micro-injection testing technology, the wellbore will have a great impact on the experimental data, making it difficult to accurately obtain formation pressure data. Summary of the Invention

[0006] The inventors of this application have discovered that the wellhead shut-in pressure data obtained using the traditional micro-injection pressure measurement method is inaccurate and affects the subsequent data interpretation.

[0007] In view of the above problems, embodiments of the present invention are proposed to provide a process string and related method for micro-injection testing that overcomes or at least partially solves the above problems.

[0008] In a first aspect, the present invention provides a process string for micro-injection testing, comprising: a continuous tubing, an anchoring tool and packer assembly, a metering shut-off valve, a centralizer, a pressure-controlled opening valve, a perforation gun, and a guide shoe, connected sequentially from top to bottom; wherein:

[0009] The continuous tubing is internally connected to the metering shut-off valve and the constant-pressure opening valve, so that when the metering shut-off valve is closed, the packer seals the annulus, and the constant-pressure opening valve is open, the liquid required for micro-injection testing is injected into the annulus through the continuous tubing and the constant-pressure opening valve.

[0010] In one embodiment, the metering shut-off valve includes a first liquid switch disposed on the side. The first liquid switch is initially in an open state to provide a liquid circulation channel for the tubing when it enters the formation. When the liquid flow rate in the tubing reaches a preset flow rate threshold, the first liquid switch is closed.

[0011] In one embodiment, the packer is used to seal the annulus of the tubing when the liquid pressure in the tubing reaches a preset first pressure threshold when the first liquid switch of the metering shut-off valve is closed.

[0012] In one embodiment, the constant pressure opening valve includes a second liquid switch disposed on the side. The second liquid switch is initially in a closed state. When the liquid pressure value in the tubing reaches a preset second pressure threshold, the second liquid switch opens and does not close again, so that the constant pressure opening valve is connected to the annulus below the packer, providing a channel for the fluid to flow out from the tubing for micro-injection testing.

[0013] In one embodiment, the coiled tubing, anchoring tool and packer assembly, metering shut-off valve, centralizer, pressure-controlled opening valve, perforating gun, and guide shoe in the process string are respectively connected by threads.

[0014] Secondly, the present invention provides a micro-injection testing method, comprising the following steps:

[0015] Install workover rig, replace wellhead crossover, install blowout preventer, and pressure test wellhead;

[0016] Tubing hanger, short section and plug valve, wellbore preparation;

[0017] Perform well cleaning and scraping operations;

[0018] Install the wellhead and pass the pressure test;

[0019] The process tubing described above is inserted, and micro-injection tests are performed using the process tubing.

[0020] In one embodiment, the micro-injection test using a process string includes:

[0021] After the tubing string is lowered to the designed depth, the depth is checked, the wellhead is installed, and the pressure test is passed.

[0022] A direct-reading pressure gauge can be installed on the wellhead tubing gate valve, or a downhole direct-reading pressure gauge can be installed according to different conditions;

[0023] The formation is opened by pressurizing and igniting a perforating gun to create a perforation.

[0024] Liquid is pumped into the tubing, and when the discharge reaches a preset flow threshold, the first liquid switch on the side of the metering shut-off valve is closed.

[0025] Continue injecting liquid into the tubing until the liquid pressure in the tubing reaches the preset first pressure threshold, at which point the packer is set to seal the annulus in the oil sleeve.

[0026] Continue injecting liquid into the tubing until the liquid pressure in the tubing reaches the preset second pressure threshold, then open the constant pressure opening valve.

[0027] A predetermined volume of liquid is slowly injected into the formation from the tubing, and flows out of the tubing through the second liquid switch of the constant pressure opening valve;

[0028] After the pumping is completed and the well is shut in, the pressure data changes are observed through the wellhead pressure gauge. When the pressure data changes to meet the design requirements, the well is shut in and the pressure measurement is completed.

[0029] In one embodiment, the above-mentioned well-draining operation includes:

[0030] Run the well gauge to the bottom of the artificial well, use clean water to displace the mud in the well, remove the well-clearing string, and check if the well gauge is deformed.

[0031] In one embodiment, the above-mentioned scraping operation includes:

[0032] The casing scraper scrapes down to the bottom of the artificial well, and the well is backwashed with clean water for more than a week to ensure that the inlet and outlet liquid properties are consistent, so as to ensure that the packer setting position is clean and free of impurities.

[0033] In one embodiment, the above-mentioned wellbore preparation includes:

[0034] The procedures for wellbore cleaning, slurry replacement, scraping, sand flushing, and plugging of the coiled tubing.

[0035] The beneficial effects of the above-mentioned technical solutions provided in the embodiments of the present invention include at least the following:

[0036] This invention provides a process string and related method for micro-injection testing. The string is formed by sequentially connecting tubing, anchoring tools and packers, a metering shut-off valve, a centralizer, a pressure-controlled opening valve, a perforating gun, and a guide shoe. When the metering shut-off valve is closed and the pressure-controlled opening valve is open, the liquid required for micro-injection testing is injected into the annulus through the continuous tubing and the pressure-controlled opening valve. This string can achieve annulus isolation during shut-in pressure testing, reducing the impact of the wellbore and significantly improving testing efficiency and the accuracy of subsequent data interpretation.

[0037] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0038] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0039] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0040] Figure 1 This is a schematic diagram of the process tubing of the present invention.

[0041] Figure 2 This is a schematic diagram of the micro-injection testing process in an embodiment of the present invention.

[0042] 1-Continuous tubing; 2-Anchoring tool and packer assembly; 3-Quantitative shut-off valve; 4-Center; 5-Pressure-controlled opening valve; 6-Perforation gun; 7-Guiding shoe. Detailed Implementation

[0043] First, it should be noted that the specific structure, features, and advantages of the present invention will be described in detail below by way of examples. However, all descriptions are for illustrative purposes only and should not be construed as limiting the present invention in any way. Furthermore, any single technical feature described or implied in the various embodiments mentioned herein can still be arbitrarily combined or deleted among these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned herein.

[0044] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0045] A new method is needed to reduce the impact of wellbore conditions and obtain more accurate pressure data, which would significantly improve testing efficiency and the accuracy of subsequent data interpretation. Currently, there is a lack of such a technical solution.

[0046] To address the problems existing in these prior art, and in order to reduce the impact of the wellbore on the micro-injection test results, embodiments of the present invention provide a process tubing and related methods for micro-injection testing.

[0047] To better understand the process string for micro-injection testing provided in the embodiments of the present invention, the concept of micro-injection testing is first explained:

[0048] Micro-injection testing, also known as micro-injection testing or fracture diagnosis testing, is a testing method that involves injecting a certain amount of liquid into the reservoir at a constant, small flow rate to cause micro-fractures in the formation and create a distribution zone around the wellbore with a pressure higher than the original formation pressure. The well is then shut in, and reservoir parameters are calculated by analyzing the pressure drop variation.

[0049] The following is a detailed description, with reference to the accompanying drawings, of a process column structure for micro-injection testing provided by an embodiment of the present invention:

[0050] Reference Appendix Figure 1 The tubing provided in this embodiment of the invention includes:

[0051] 1. Coiled tubing; 2. Anchoring tool and packer assembly; 3. Metering shut-off valve; 4. Centralizer; 5. Pressure-controlled opening valve; 6. Perforation gun; 7. Guide shoe.

[0052] The continuous tubing 1 is internally connected to the quantitative shut-off valve 3 and the constant pressure opening valve 5, so that when the quantitative shut-off valve 3 is closed, the packer 2 seals the annulus, and when the constant pressure opening valve 5 is opened, the liquid required for micro-injection testing is injected into the annulus through the continuous tubing 1 and the constant pressure opening valve 5.

[0053] In one embodiment, the aforementioned metering shut-off valve 3 includes a first liquid switch disposed on the side. The first liquid switch is initially in an open state, so as to provide a liquid circulation channel for the tubing when it enters the formation. When the liquid flow rate in the tubing reaches a preset flow rate threshold, the first liquid switch is closed.

[0054] The quantitative shut-off valve 3 provides a circulation channel for the tubing during the tubing insertion process. This valve closes based on the flow rate, and the closing flow rate can be designed according to specific conditions to meet different operating requirements.

[0055] In one embodiment, the packer 2 is used to seal the annulus when the liquid pressure in the tubing reaches a preset first pressure threshold when the first liquid switch of the metering shut-off valve 3 is closed.

[0056] After the packer 2 is set, it seals the annulus of the oil casing, which can reduce the impact of the annulus volume on the pressure measurement data during the well shut-in pressure measurement process.

[0057] In one embodiment, the pressure-regulating valve 5 includes a second liquid switch disposed on the side. The second liquid switch is initially in a closed state. When the liquid pressure in the tubing reaches a preset second pressure threshold, the second liquid switch opens and does not close again, so that the pressure-regulating valve 5 is connected to the annulus below the packer 2, providing a channel for the fluid to flow out from the tubing for micro-injection testing.

[0058] In the above description, for the sole purpose of distinction, the hole on the side of the quantitative shut-off valve is referred to as the first liquid switch, and the hole on the side of the constant pressure open valve is referred to as the second liquid switch.

[0059] The continuous tubing is internally connected to the metering shut-off valve and the constant-pressure opening valve. In this way, even when the metering shut-off valve is closed, liquid can continue to be injected through the continuous tubing until a certain pressure is reached, at which point the packer seals the annulus and the pressure threshold for the constant-pressure opening valve to open is reached.

[0060] In one embodiment, the constant pressure opening valve 5 is operated to close by pressure and belongs to the control tool category. When this valve is open, it can connect the annulus below the packer 2, providing a liquid outflow channel for micro-injection testing. This valve is a one-time opening and closing tool and will not be closed after opening.

[0061] In one embodiment, the coiled tubing 1, the anchoring tool and packer assembly 2, the metering shut-off valve 3, the centralizer 4, the pressure-controlled opening valve 5, the perforating gun 6, and the guide shoe 7 in the process tubing are respectively connected by threads.

[0062] Based on the aforementioned process string for micro-injection testing, this embodiment of the invention also provides a micro-injection testing method, referring to... Figure 2 As shown, it includes the following steps:

[0063] S1, Install workover rig, replace wellhead cross-connector, install blowout preventer, and perform wellhead pressure test;

[0064] S2, tubing hanger, short section and plug valve, wellbore preparation;

[0065] S3, perform well cleaning and scraping operations;

[0066] S4, Install the wellhead tree and pass the pressure test;

[0067] S5, the process column provided in the aforementioned embodiment is inserted, and the micro-injection test is performed using the process column.

[0068] In one embodiment, combined Figure 1 The structure of the process tubing shown above, in step S5, can be specifically tested using the following method:

[0069] After the tubing string is lowered to the designed depth, the depth is checked, the wellhead is installed, and the pressure test is passed.

[0070] A direct-reading pressure gauge is installed on the wellhead tubing gate valve;

[0071] The formation was opened by pressurizing and igniting the perforation gun 6.

[0072] Liquid is pumped into the tubing, and when the discharge reaches a preset flow threshold, the first liquid switch on the side of the metering shut-off valve 3 is closed.

[0073] Continue injecting liquid into the tubing until the liquid pressure in the tubing reaches the preset first pressure threshold, at which point the packer 2 is set to seal the annulus in the oil sleeve.

[0074] Continue injecting liquid into the tubing until the liquid pressure in the tubing reaches the preset second pressure threshold, then open the constant pressure opening valve 5;

[0075] A preset volume of liquid is slowly injected into the formation from the tubing, and flows out of the tubing through the second liquid switch of the constant pressure opening valve 5;

[0076] After the pumping is completed and the well is shut in, the pressure data changes are observed through the wellhead pressure gauge. When the pressure data changes to meet the design requirements, the well is shut in and the pressure measurement is completed.

[0077] The following example of a specific micro-injection test illustrates the above-mentioned micro-injection test method.

[0078] The method for performing micro-injection testing using the above-mentioned tubing string includes the following steps:

[0079] 1) Install the workover rig, replace the wellhead crossover, install the blowout preventer, and perform a wellhead pressure test; install tubing hangers, short sections, and plug valves;

[0080] 2) Well Cleaning. Run the well gauge to the bottom of the artificial well to confirm the actual depth. Displace the mud in the well with clean water. Remove the well cleaning string and check the well gauge for deformation.

[0081] 3) Scraping. Use a casing scraper to scrape down to the artificial well bottom position (repeatedly scrape the packer setting position three times) until the suspended weight is normal and there is no obstruction indication. Backwash the well with clean water for at least one week to ensure consistent inlet and outlet fluid properties. Ensure the packer setting position is clean and free of impurities.

[0082] 4) Install the wellhead and pass the pressure test;

[0083] 5) Lower the aforementioned tubular column to a depth that coincides with the position of the guide shoe;

[0084] 6) Utilize this tubing string to implement micro-injection pressure measurement technology:

[0085] 7) Install a direct-reading pressure machine on the wellhead tubing gate valve;

[0086] 8) Perforating gun 6 pressurized ignition perforation;

[0087] 9) Pump liquid into the tubing through pipe 1 to achieve a discharge rate of 15m³. 3 / h, reaching the preset first pressure threshold, the first liquid switch of the quantitative shut-off valve 3 is closed, at which time the liquid outlet is blocked, and the liquid only flows in the tubing;

[0088] 10) Continue pumping liquid into tubing 1. When the pressure in the tubing string reaches 18 MPa (preset first pressure threshold), packer 2 sets to seal the annulus in the tubing.

[0089] 11) Continue injecting liquid, and the pressure in the tubing rises to 25 MPa (preset second pressure threshold). At this time, the pressure value reaches the opening degree of the constant pressure opening valve 5. The second liquid switch of the constant pressure opening valve 5 is opened, providing a channel for the fluid to flow from inside the tubing to the outside for micro-injection test.

[0090] 12) After the constant pressure opening valve 5 is opened, control the amount of liquid injected into the formation from the oil pipe 1, and slowly inject 10m of liquid into the formation from the oil pipe 1. 3 liquid;

[0091] 13) After the pumping is completed, shut in the well and observe the pressure data changes through the wellhead pressure gauge. When the pressure data changes reach the design requirements, shut in the well and the pressure measurement ends.

[0092] 14) Finally, the pressure of low-permeability and ultra-low-permeability reservoirs such as shale oil and gas layers is obtained through data interpretation.

[0093] The micro-injection pressure testing method proposed in this embodiment of the invention, under the matching tubing process provided in this embodiment of the invention, when the tubing reaches the designated position, before pressure testing, the annulus of the casing is set by a setting device to reduce the annulus volume of the wellbore, and then the micro-injection test fluid is provided to flow out through the opening of the constant pressure opening valve to perform pressure testing, thereby realizing micro-injection testing.

[0094] This invention provides a process string and related method for micro-injection testing. The string is formed by sequentially connecting tubing, anchoring tools and packers, a metering shut-off valve, a centralizer, a pressure-controlled opening valve, a perforating gun, and a guide shoe. When the metering shut-off valve is closed and the pressure-controlled opening valve is open, the liquid required for micro-injection testing is injected into the annulus through the continuous tubing and the pressure-controlled opening valve. This string can achieve annulus isolation during shut-in pressure testing, reducing the impact of the wellbore and significantly improving testing efficiency and the accuracy of subsequent data interpretation.

[0095] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A process string for micro-injection testing, characterized in that, include: The components connected from top to bottom are: coiled tubing, anchoring tool and packer assembly, metering shut-off valve, centralizer, pressure-controlled opening valve, perforating gun, and guide shoe; among which: The continuous tubing is internally connected to the metering shut-off valve and the constant pressure opening valve, so that when the metering shut-off valve is closed, the packer seals the annulus, and the constant pressure opening valve is open, the liquid required for micro-injection testing is injected into the annulus through the continuous tubing and the constant pressure opening valve. The metering shut-off valve includes a first liquid switch disposed on the side. The first liquid switch is initially in the open state to provide a liquid circulation channel for the tubing when it enters the formation. When the liquid flow rate in the tubing reaches a preset flow rate threshold, the first liquid switch is closed. The packer is used to seal the annulus of the oil sleeve when the liquid pressure in the tubing reaches a preset first pressure threshold when the first liquid switch of the metering shut-off valve is closed. The constant pressure opening valve includes a second liquid switch disposed on the side. The second liquid switch is initially in a closed state. When the liquid pressure value in the tubing reaches a preset second pressure threshold, the second liquid switch opens and does not close again, so that the constant pressure opening valve is connected to the annulus below the packer, providing a channel for the fluid to flow out from the tubing for micro-injection testing.

2. The process tubing according to claim 1, characterized in that, The coiled tubing, anchoring tool and packer assembly, metering shut-off valve, centralizer, pressure-controlled opening valve, perforating gun, and guide shoe in the process string are all connected by threads.

3. A micro-injection testing method, characterized in that, Includes the following steps: Install workover rig, replace wellhead crossover, install blowout preventer, and pressure test wellhead; Tubing hanger, short section and plug valve, wellbore preparation; Perform well cleaning and scraping operations; Install the wellhead and pass the pressure test; The process column as described in claim 1 or 2 is inserted, and micro-injection testing is performed using the process column; The micro-injection test using the process tubing includes: After the tubing string is lowered to the designed depth, the depth is checked, the wellhead is installed, and the pressure test is passed. A direct-reading pressure gauge is installed on the wellhead tubing gate valve; The formation is opened by pressurizing and igniting a perforating gun to create a perforation. Liquid is pumped into the tubing, and when the discharge reaches a preset flow threshold, the first liquid switch on the side of the metering shut-off valve is closed. Continue injecting liquid into the tubing until the liquid pressure in the tubing reaches the preset first pressure threshold, at which point the packer is set to seal the annulus in the oil sleeve. Continue injecting liquid into the tubing until the liquid pressure in the tubing reaches the preset second pressure threshold, then open the constant pressure opening valve. A predetermined volume of liquid is slowly injected into the formation from the tubing, and flows out of the tubing through the second liquid switch of the constant pressure opening valve; After the pumping is completed and the well is shut in, the pressure data changes are observed through the wellhead pressure gauge. When the pressure data changes to meet the design requirements, the well is shut in and the pressure measurement is completed.

4. The method according to claim 3, characterized in that, The well cleaning operation includes: Run the well gauge to the bottom of the artificial well, use clean water to displace the mud in the well, remove the well-clearing string, and check if the well gauge is deformed.

5. The method according to claim 4, characterized in that, The scraping operation includes: The casing scraper scrapes down to the bottom of the artificial well, and the well is backwashed with clean water for more than a week to ensure that the inlet and outlet liquid properties are consistent, so as to ensure that the packer setting position is clean and free of impurities.

6. The method according to claim 4, characterized in that, The wellbore preparation includes: The procedures for wellbore cleaning, slurry replacement, scraping, sand flushing, and plugging of the coiled tubing.

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