Micro-acidizing downhole formation testing device and micro-acidizing method based thereon

Abstract

This invention provides a micro-acidification downhole formation testing device and a micro-acidification method based thereon. The device includes a hydraulic power module, a compartmentalized acid-carrying unit, an acid injection / discharge pump unit, a probe module, a downhole observation chamber for acid-formation reaction, a pipeline system, and a control circuit. The hydraulic module is configured to drive tool movements and control the testing process via hydraulic power. The acid injection / discharge unit is configured to control fluid flow, circulation, and pressure regulation. The injection probe of the probe module is seated at the target acidification or acid fracturing test injection point, connecting the device to the formation. The downhole observation chamber for acid-formation reaction is configured to monitor the physical / chemical parameters during injection / discharge. This invention effectively solves the problems of acid system and acid formulation screening, optimization, and process optimization in real-world acid environments within formations.

Description

Technical Field

[0001] This invention relates to the field of petroleum exploration and development engineering technology, and to a micro-acidification downhole formation testing device and a micro-acidification method based thereon. Background Technology

[0002] Acidizing and acid fracturing are important measures for enhancing oil and gas well production, injection, and reservoir stimulation in oil and gas field development. By injecting acid into the formation to dissolve carbonate rocks, clay minerals, and other components, or by injecting acid into the formation at pressures exceeding rock fracturing pressure to create fractures, acid effectively improves near-wellbore contamination and increases reservoir permeability, thereby increasing oil and gas well production. A crucial factor in the effectiveness of acidizing and acid fracturing lies in using appropriate acid systems, formulations, and implementation processes. Currently, the oil and gas industry involves dozens of acid systems, hundreds of acid formulations, and complex and diverse process parameters. Existing methods for selecting acids and processes typically employ laboratory testing and analysis, evaluating the effectiveness of candidate acids through core displacement experiments to optimize the appropriate acid system and implementation process. The main drawbacks of this method are its high dependence on downhole core samples, high experimental costs, poor timeliness, and difficulty in fully simulating the downhole temperature and pressure environment, leading to significant experimental errors. Inappropriate use of acid and implementation process can easily lead to excessively rapid reaction between the acid and the formation, short acid penetration distance, and other effects, resulting in poor stimulation effect. This has been the main problem faced by reservoir acidizing and acid fracturing stimulation for a long time. Summary of the Invention

[0003] The purpose of this invention is to provide a micro-acidification downhole formation testing device and a micro-acidification method based thereon, which can effectively solve the problems of acid system and acid formulation screening, optimization and process optimization in real acid use environment. This innovation avoids the high cost and long cycle problems caused by the lack of actual formation cores or the need to collect cores first in conventional acid screening. It can realize in-situ monitoring of acid reaction with formation and quantitative evaluation of acid use effect.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a micro-acidizing downhole formation testing device, comprising a hydraulic power module, a compartmentalized acid-carrying unit, an acid injection / discharge unit, a probe module, a downhole observation chamber for acid-formation reaction, a pipeline system, and a control circuit;

[0005] The hydraulic power module is used to drive the movement of the acid injection / discharge unit and control the testing process. The acid injection / discharge unit is configured to control fluid flow, circulation and pressure regulation; for example, to control the fluid flow, circulation and pressure regulation of the compartment-type acid-carrying unit, and can also be used to control other modules such as connecting pipeline systems.

[0006] The probe module is configured to contact and communicate with the formation. The probe module includes an injection probe, which is seated at the injection point of the target acidification or acid fracturing test, connecting the device to the formation.

[0007] The pipeline system includes multiple pipelines, and the pipeline system and the control circuit are respectively connected to the compartmentalized acid carrying unit, the acid injection / discharge unit, the probe module, and the downhole observation chamber for acid and formation reaction;

[0008] The downhole observation chamber for acid-formation reaction is configured to monitor physical / chemical parameters during injection / drainage.

[0009] Furthermore, it also includes a power supply module, which is configured to provide power to the entire device and ensure the normal operation of each functional unit of the instrument.

[0010] Furthermore, preferably, the compartmentalized acid-carrying unit includes several independent acid-carrying compartments, each of which is connected to the injection probe via a pipeline.

[0011] Furthermore, the acid injection / discharge unit is preferably a discharge pump.

[0012] Furthermore, the device preferably includes a traction unit configured to lift or lower the device to change its position, and / or the traction unit is also used to provide a data transmission medium. A separate data transmission module may also be provided for data transmission.

[0013] Furthermore, the probe module preferably also includes a probe support, which is disposed on the outer wall surface of the probe module and extends to the formation at one end to support the injection probe.

[0014] Furthermore, the probe support is preferably at least one of a hydraulic support, a spring support, and a rubber support.

[0015] Furthermore, the downhole observation chamber for the reaction of acid with the formation preferably includes a combination of components for monitoring physical and chemical parameters such as pressure, flow rate, pH value, density, resistivity, and viscosity.

[0016] This invention also provides a micro-acidification method based on a micro-acidification downhole formation testing device, comprising the following steps:

[0017] S1. Different systems and component ratios of acid are configured on the ground and poured into compartmentalized acid carrying units, with each acid being placed independently in a different acid carrying compartment.

[0018] S2. The device is brought into the well by the traction unit and landed in the injection formation after acid testing and analysis.

[0019] S3. The extrusion probe of the probe module is seated at the designed acidification or acid fracturing test extrusion point, connecting the device with the formation to form a closed test environment;

[0020] S4. By injecting / draining acid to extract formation fluids, high-precision pressure sensors are used to collect formation fluid pressure data in real time and simultaneously record pressure decay / recovery curves to determine the formation's seepage capacity.

[0021] S5. Open a certain acid-carrying chamber or open different acid-carrying chambers step by step according to the process design. Squeeze the acid into the formation through the acid injection / drainage unit according to the designed process or sequence. During the squeezing process, monitor the physical / chemical parameters of the reaction between the acid and the formation through the downhole observation chamber. The data is transmitted to the surface to observe the reaction effect between the acid and the formation in real time.

[0022] S6. Unseal the injection point and move it to a new acid injection point using the traction unit. Repeat steps S4 to S5 above to test the formation seepage capacity and the reaction effect of acid or acid combination with the formation at the second injection point.

[0023] S7. Repeat S3 to S6 to test the reaction effect of different acid-carrying tank acid or acid combination with the formation in sequence.

[0024] S8. Based on the reaction time between the acid and the formation, after settling, return to the completed acid injection test point and reverse pump through the acid injection / drainage unit. During the process, monitor various physical / chemical parameters and formation fluid pressure data through the downhole observation room for the reaction between the acid and the formation. Monitor the effects of the acid reaction on the formation, such as unblocking, decontamination, and improving formation pore throat connectivity, to enhance permeability.

[0025] S9. Shrink the acid injection probe, unseal it, lift the device to the ground, and complete the micro-acidification or acid pressure test.

[0026] The micro-acidification downhole formation testing device and method provided by this invention have the following beneficial effects:

[0027] 1. Flexible carrying and injection of acid: Through the compartmentalized acid carrying unit, acid of different systems and component ratios can be carried flexibly, and acid can be selectively injected as needed.

[0028] 2. Real-time monitoring of reaction effects: Through the downhole observation chamber for the reaction between acid and formation, the reaction effects between acid and formation can be monitored in real time, including physical / chemical parameters such as pressure, flow rate, pH value, density, resistivity, and viscosity.

[0029] 3. Accurately assess the acidizing effect: By coordinating the injection / drainage unit and the downhole observation chamber for acid and formation reaction, and comparing the pressure decay / recovery curves before and after acid injection, the effect of acidizing treatment can be accurately assessed, including the effect on unblocking the formation and improving permeability. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0031] Figure 1 This is a schematic diagram of the operation of the micro-acidification downhole formation testing device of the present invention;

[0032] Figure 2 This is a schematic diagram of monitoring data for the micro-acidification acid extrusion process in one embodiment;

[0033] Figure 3 This is a schematic diagram of monitoring data for the micro-acidification backflow process in one embodiment. Detailed Implementation

[0034] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0035] A component is referred to as being "fixed to" or "set on" another component, and it may be located directly or indirectly on that other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to that other component.

[0036] The terms "upper," "lower," "left," "right," "front," "back," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or position based on the accompanying drawings and are used only for ease of description, and should not be construed as limiting the technical solution. The terms "first," "second," etc., are used only for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. "Multiple" means two or more, unless otherwise explicitly defined.

[0037] like Figure 1 As shown, a micro-acidizing downhole formation testing device includes a compartmentalized acid-carrying unit 10, a hydraulic power module, an acid injection / discharge unit 20, a probe module 40, an acid-formation reaction downhole observation chamber 30, a pipeline system 60, and a control circuit.

[0038] The compartmentalized acid carrying unit 10 includes several independent acid carrying chambers 11, each of which is connected to the injection probe 41 of the acid injection / discharge unit 20, for carrying acid with different systems and component ratios.

[0039] The hydraulic power module 80 is used to drive the movement of the acid injection / discharge unit 20 and control the test process. The acid injection / discharge unit 20 is configured to control fluid flow, circulation and pressure regulation. For example, it can control the fluid flow, circulation and pressure regulation of the compartment-type acid-carrying unit 10, and can also be used to control other modules such as the connecting pipeline system 60.

[0040] The probe module 40 is configured to carry an injection probe 41, which is seated at the injection point of the target acidification or acid fracturing test and connects the device to the formation.

[0041] The pipeline system 60 includes multiple pipelines. The pipeline system 60 and the control circuit are respectively connected to the compartmentalized acid carrying unit 10, the acid injection / discharge unit 20, the probe module 40, and the downhole observation chamber for acid and formation reaction 30, and are used to control the operation of the entire device.

[0042] The downhole observation chamber 30 for acid-formation reaction is configured to monitor physical / chemical parameters during injection, including pressure, flow rate, pH value and / or viscosity, and transmit the data to the surface multi-element combination module via a data transmission module.

[0043] Furthermore, it also includes a power supply module 70, which is configured to provide power to the entire device to ensure the normal operation of each functional unit of the instrument.

[0044] In one specific embodiment, the compartmentalized acid-carrying unit 10 includes several independent acid-carrying chambers 11, such as 3-6 acid-carrying chambers 11, each of which is connected to the injection probe 41. Further, the entire device may include multiple compartmentalized acid-carrying units 10.

[0045] In one specific embodiment, the acid injection / discharge unit 20 is a discharge pump used to control fluid flow, circulation and pressure regulation for the compartmentalized acid carrying unit 10.

[0046] In one embodiment, the device further includes a traction unit 50 configured to lift or lower the device to change its position. The traction unit 50 may be a crane, traction device, cable, drill rod, or other means. When it is a cable, drill rod, or wire, it can also be used to provide a data transmission medium.

[0047] In one specific embodiment, the probe module 40 further includes a probe support 42, which is disposed on the outer wall surface of the probe module 40 and extends to the formation at one end to support the injection probe 41. This prevents excessive traction force from causing incorrect injection or suction position when the injection probe 41 injects liquid or reverses the formation liquid, thereby affecting the detection results and improving the stability of the device and the accuracy of data detection.

[0048] In a preferred embodiment, the probe support 42 is at least one of a hydraulic support, a spring support, and a rubber support.

[0049] In a preferred embodiment, the downhole observation chamber 30 for acid-formation reaction includes a combination of components for monitoring physical parameters such as pressure, flow rate, pH value, and viscosity.

[0050] In this application, the positions of the functional modules in the device can be combined in different ways according to engineering requirements. For example, the probe module 40 can be at the bottom, or it can be set between the acid injection / drainage unit 20 and the downhole observation chamber 30 for acid and formation reaction. No specific limitation is made.

[0051] This invention also provides a micro-acidification method based on a micro-acidification downhole formation testing device, comprising the following steps:

[0052] S1. Different systems and component ratios of acid solutions are configured on the surface and poured into the compartmentalized acid carrying unit, with each acid solution placed independently in a different acid carrying compartment.

[0053] S2. The device is brought into the well by the traction unit and landed in the injection formation after acid testing and analysis.

[0054] S3. The injection probe of the probe module is seated at the designed acidification or acid fracturing test injection point, connecting the device with the formation to form a closed test environment.

[0055] S4. By injecting / draining acid to extract formation fluid, high-precision pressure sensors are used to collect formation fluid pressure data in real time and simultaneously record pressure decay / recovery curves to determine formation seepage capacity.

[0056] S5. Open a certain acid-carrying chamber or open different acid-carrying chambers in stages according to the process design. Squeeze the acid into the formation through the acid injection / drainage unit according to the designed process or sequence. During the squeezing process, monitor the physical / chemical parameters of the reaction between the acid and the formation through the downhole observation chamber. The data is transmitted to the surface to observe the reaction effect between the acid and the formation in real time.

[0057] S6. Unseal the injection point and move it to a new acid injection point using the traction unit. Repeat steps S4 to S5 above to test the formation seepage capacity and the reaction effect of acid or acid combination with the formation at the second injection point.

[0058] S7. Repeat S3 to S6 to test the reaction effect of different acid-carrying chambers or acid combinations with the formation.

[0059] S8. Based on the reaction time between the acid and the formation, after settling, return to the completed acid injection test point and reverse pump through the acid injection / drainage unit. During the process, monitor various physical / chemical parameters and formation fluid pressure data through the downhole observation room for the reaction between the acid and the formation. Monitor the effects of the acid reaction on the formation in terms of unblocking, decontamination, improving formation pore throat connectivity and increasing permeability.

[0060] S9. Shrink the acid injection probe, unseal it, lift the device to the ground, and complete the micro-acidification or acid pressure test.

[0061] In one specific embodiment, a carbonate reservoir was discovered during drilling in an offshore oil and gas block. The reservoir is characterized by high porosity and low permeability, and conventional testing cannot release production capacity; acidizing is required to achieve this. The selection of a suitable acid solution is a crucial issue before acidizing operations. Using a micro-acidizing downhole formation testing device, the following prepared acid solutions were injected into the six acid-carrying chambers of a compartmentalized acid-carrying unit: chelated acid + gel acid (tank 1), chelated acid + low-viscosity gel acid (tank 2), low-viscosity gel acid + fluoroboric acid (tank 3), composite chelated acid formula 1 (tank 4), composite chelated acid formula 2 (tank 5), and composite chelated acid formula 3 (tank 6).

[0062] After the instrument is assembled, it is lowered into the well using a cable. First, the injection probe of the probe module is positioned at the No. 1 test point of the carbonate reservoir by measuring the depth calibration curve. The probe is then pushed against the well wall and sealed using hydraulic control to establish the connection between the injection probe and the formation.

[0063] Open the inlet / outlet valve (switch) of acid storage tank No. 1, and inject / drain the acid from the acid-carrying tank into the formation at a constant rate through the acid injection / drainage unit. During the injection process, monitor parameters including pressure, pump rate (pump speed), cumulative pump rate, and pH value through the downhole observation room for acid-formation reaction until all the acid in tank No. 1 is injected. Set the acid to react with the formation for 2 hours. During this period, unseal the probe to test point No. 2 in the formation for acid injection testing. Open tank No. 2 and repeat the acid injection test process of No. 1, monitoring and recording relevant data. Perform acid injection experiments on tanks No. 3, 4, 5, and 6 at test points at depths of 3, 4, 5, and 6 in sequence. Figure 2 As shown.

[0064] After the acid extraction at point 1 was completed and allowed to stand for two hours, the instrument was returned to test point 1. After the probe was sealed, the pump was used to reverse the flow (reverse pumping) of fluid. During this process, various parameters such as pressure, pump speed, residual acid ratio, formation fluid (gas or oil) volume, and pH value were monitored in the downhole observation chamber through the acid-formation reaction. Figure 3As shown. Then, based on the standing reaction time of each acid extraction point, the backflow tests of test points 2, 3, 4, 5, and 6 were completed in sequence and the data were recorded.

[0065] Unseal and lift the instrument to complete the micro-acidification test.

[0066] By comparing the backflow rate, residual acid ratio, and pressure changes during injection and backflow at each micro-acidification test point, the acidification effect of the six acid solutions was comprehensively judged, and a suitable acid solution was selected for large-scale acidification in the later stage.

[0067] The micro-acidification downhole formation testing device and method provided by this invention have the following beneficial effects:

[0068] 1. Flexible carrying and injection of acid: Through the compartmentalized acid carrying unit, acid of different systems and component ratios can be carried flexibly, and acid can be selectively injected as needed.

[0069] 2. Real-time monitoring of reaction effects: Through the downhole observation chamber for the reaction between acid and formation, the reaction effects between acid and formation can be monitored in real time, including physical parameters such as pressure, flow rate, pH value, density, resistivity and / or viscosity.

[0070] 3. Accurately assess the acidizing effect: By coordinating the injection / drainage unit and the downhole observation chamber for acid and formation reaction, and comparing the pressure decay / recovery curves before and after acid injection, the effect of acidizing treatment can be accurately assessed, including the effect on unblocking the formation and improving permeability.

[0071] 4. Improve acidification efficiency: Through the cooperation of the traction unit and probe module, the device can be quickly moved to different acid injection points, thereby improving the efficiency of acidification.

[0072] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A micro-acidification downhole formation testing device, characterized in that, It includes a hydraulic power module, a compartmentalized acid-carrying unit, an acid injection and / or drainage unit, a probe module, a downhole observation chamber for acid-formation reaction, a pipeline system, and control circuitry. The hydraulic power module is used to drive the movement of the acid injection and / or drainage unit and control the test process. The acid injection and / or drainage unit is configured to control fluid flow, circulation, and pressure regulation. The probe module is configured to contact and communicate with the formation. The probe module includes an injection probe, which is seated at the injection point of the target acidification or acid fracturing test, connecting the device to the formation. The pipeline system and control circuit are respectively connected to the compartmentalized acid carrying unit, the acid injection and / or drainage unit, the probe module, and the downhole observation chamber for acid and formation reaction. The downhole observation chamber for acid-formation reaction is configured to monitor physical and / or chemical parameters during injection and / or drainage. The downhole observation chamber for acid-formation reaction includes a combination of components for monitoring physical and / or chemical parameters such as pressure, flow rate, pH value, density, resistivity and / or viscosity. Each of the compartmentalized acid-carrying units includes several independent acid-carrying compartments, and each acid-carrying compartment is connected to the injection probe via a pipeline.

2. The micro-acidification downhole formation testing device according to claim 1, characterized in that, The device includes multiple compartmentalized acid-carrying units.

3. The micro-acidification downhole formation testing device according to claim 1, characterized in that, The acid injection and / or drainage unit is a drainage pump.

4. The micro-acidification downhole formation testing device according to claim 1, characterized in that, The device also includes a traction unit configured to lift or lower the device to change its position, and / or the traction unit is also used to provide a data transmission medium.

5. The micro-acidification downhole formation testing device according to claim 1, characterized in that, The probe module also includes a probe support, which is disposed on the outer wall of the probe module and extends to the formation at one end to support the injection probe.

6. The micro-acidification downhole formation testing device according to claim 5, characterized in that, The probe support is at least one of a hydraulic support, a spring support, and a rubber support.

7. A micro-acidification method based on the micro-acidification downhole formation testing device according to any one of claims 1-6, Its features are, Includes the following steps: S1. Different systems and component ratios of acid are configured on the ground and poured into compartmentalized acid carrying units, with each acid being placed independently in a different acid carrying compartment. S2. The device is brought into the well by the traction unit and landed in the injection formation after acid testing and analysis. S3. The extrusion probe of the probe module is seated at the designed acidification or acid fracturing test extrusion point, connecting the device with the formation to form a closed test environment; S4. Extract formation fluids through acid injection and / or drainage units, collect formation fluid pressure data in real time using high-precision pressure sensors, and record pressure decay or recovery curves simultaneously to determine formation seepage capacity. S5. Open a certain acid-carrying chamber or open different acid-carrying chambers step by step according to the process design. Squeeze the acid into the formation through the acid injection and / or drainage unit according to the designed process or sequence. During the squeezing process, monitor the physical and / or chemical parameters of the reaction between the acid and the formation through the downhole observation chamber. The data is transmitted to the surface to observe the reaction effect between the acid and the formation in real time. S6. Unseal the injection point and move it to a new acid injection point using the traction unit. Repeat steps S4 to S5 above to test the formation seepage capacity and the reaction effect of acid or acid combination with the formation at the second injection point. S7. Repeat S3 to S6 to test the reaction effect of different acid-carrying tank acid or acid combination with the formation in sequence. S8. Based on the reaction time between the acid and the formation, after settling, return to the completed acid injection test point and reverse pump through the acid injection and / or drainage unit. During the process, monitor various physical and / or chemical parameters and formation fluid pressure data through the downhole observation room for the reaction between the acid and the formation. Monitor the effects of the acid reaction on the formation in terms of unblocking, decontamination, improving formation pore throat connectivity and permeability. S9. Shrink the acid injection probe, unseal it, lift the device to the ground, and complete the micro-acidification or acid pressure test.

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