Downhole permeability monitoring apparatus for hydrate

Abstract

A downhole permeability monitoring apparatus for a hydrate, comprising a sealed housing (1), a pressure system, a fluid isolation system, a control and data processing system, a measurement system, and a plurality of valves. The fluid isolation system confines the sealed housing (1) in a test section; a pressure value in the test section is measured by means of the measurement system; the pressure value in the test section is adjusted by means of the pressure system, so as to disturb the pressure in the test section; and by means of a variation in the pressure value, a pressure variation curve is obtained, so as to calculate the permeability of a hydrate reservoir.

Description

A hydrate downhole permeability monitoring device Technical fields:

[0001] This invention relates to the field of natural gas hydrate reservoir permeability monitoring technology, and specifically to a hydrate downhole permeability monitoring device. Background technology:

[0002] Currently, the most commonly used field testing method for the effective absolute permeability of hydrate reservoirs is the cable formation test. The cable formation test involves lowering a tool into the wellbore using a cable, extracting a small fluid sample from the reservoir, and simultaneously recording the reservoir pressure response during the production phase and the subsequent shut-in phase.

[0003] Cable formation testing can be applied to both open-hole and cased wells. It allows for the collection of fluid samples at different depths within the reservoir and the testing of permeability, revealing the vertical distribution of reservoir permeability.

[0004] In hydrate field testing, Schlumberger's Modular Cable Formation Dynamic Tester (MDT) is mostly used. However, due to limitations in the pump's fluid extraction capacity, the pressure reduction capability of the cable formation test is insufficient, resulting in a small pressure wave influence range. Consequently, the permeability obtained is only the average permeability of the reservoir within a small area around the wellbore, which is easily affected by hydrate decomposition and drilling fluid mud skin. The permeability measurement results may be much lower than the permeability of uncontaminated reservoirs. Summary of the Invention:

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies such as the small detection range of cable formation testing equipment, the susceptibility of formation pressure response to hydrate decomposition, and the influence of drilling fluid mud skin. This invention provides a hydrate downhole permeability monitoring device, wherein a low-pressure tank is connected to the hydrate reservoir, and the permeability of the hydrate reservoir is calculated by monitoring the pressure recovery curve in the low-pressure tank.

[0006] To address the problems existing in the prior art, the present invention adopts the following technical solution:

[0007] A hydrate downhole permeability monitoring device includes a sealed housing, a pressure system, a fluid isolation system, a control and data processing system, a detection system, and multiple valve bodies;

[0008] The control and data processing system is connected to the pressure system, the fluid isolation system, the detection system, and the plurality of valve bodies, respectively.

[0009] The control and data processing system is used to control the start and stop of the pressure system, the fluid isolation system and the detection system, as well as to control the opening and closing of the plurality of valve bodies;

[0010] The sealed housing forms an accommodating space that communicates with the outside world;

[0011] The pressure system is disposed in the accommodating space. The pressure system includes a pressure supply system and a pressure control system. The pressure supply system is used to provide pressure. The pressure control system is used to adjust the pressure within the test section.

[0012] The fluid isolation system is installed on the sealing housing. The fluid isolation system is used to restrict the sealing housing within the test section of the test well and to prevent fluids outside the test section from entering the test section.

[0013] The detection system includes multiple pressure sensors, which are used to monitor the pressure value of the pressure system and transmit the pressure value data to the control and data processing system.

[0014] The fluid isolation system confines the sealed housing within the test section. The detection system detects the pressure value within the test section. The pressure system adjusts the pressure value within the test section to disturb the pressure. By observing the pressure changes, a pressure change curve is obtained to calculate the hydrate reservoir permeability.

[0015] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, the pressure supply system includes a pressure source, which is a pressure device loaded with fluid, and the pressure device is arranged in the accommodating space.

[0016] Both the sealing housing and the pressure device are provided with multiple openings, including a pressure balance port, a fluid inlet / outlet, and a first through hole; wherein the fluid inlet / outlet includes a fluid inlet and a fluid outlet.

[0017] The pressure balance port and fluid inlet / outlet on the sealing housing and the pressure balance port and fluid inlet / outlet on the pressure device are respectively provided and connected by fluid pipes; the first through hole on the sealing housing is the wire harness outlet and the first through hole on the pressure device is the piston through hole.

[0018] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, the pressure control system includes a pressure reduction system mounted on the pressure supply system via a bracket;

[0019] The pressure reduction system includes a drive device, a transmission device, and a piston; wherein the piston is disposed in the pressure appliance, and the piston rod passes through the piston through hole;

[0020] The driving device drives the piston rod of the piston to move up and down along the axis of the pressure device through the transmission device;

[0021] When the piston rod moves upward, it reduces the pressure inside the pressure device, making the pressure lower than the formation pressure; when the piston rod moves downward, it discharges the fluid that entered the pressure device.

[0022] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, the driving device is a motor and the transmission device is a gear transmission device;

[0023] The gear transmission device includes a first connecting member and a second connecting member, the second connecting member being fixed on the first connecting member; the drive shaft of the motor is connected to the second connecting member, a screw is connected to the outside of the first connecting member, and the piston rod passes through the first connecting member and the second connecting member;

[0024] When the drive shaft of the motor rotates, it drives the first connecting member and the second connecting member to move on the piston rod, and at the same time drives the first connecting member and the second connecting member to move on the screw.

[0025] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, the control and data processing system includes a controller and a data center connected by a wiring harness. The data center is located outside the test well, and the controller is detachably installed in the accommodating space. The wiring harness passes through the wiring harness outlet and connects the controller and the control center.

[0026] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, filters are provided on both the fluid inlet and outlet of the sealed housing.

[0027] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, the fluid isolation system includes a gas storage tank and a rubber tire connected by a gas pipeline;

[0028] A valve body is installed on the gas pipeline, and both the gas storage tank and the valve body are connected to the control and data processing system to control the gas intake of the gas pipeline;

[0029] The gas storage tank is detachably installed in the accommodating space, and the rubber tire is installed at both ends of the sealed housing.

[0030] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, multiple valve bodies are all solenoid valves.

[0031] As an improvement to the technical solution of the hydrate downhole permeability monitoring device of the present invention, a plurality of pressure sensors are installed on the pressure device of the pressure system and / or the gas storage tank of the fluid isolation system.

[0032] The beneficial effects of this invention are:

[0033] In this invention, a pressure disturbance method is used. When the pressure is restored, a pressure recovery curve is obtained, and then the permeability of the hydrate reservoir is calculated. This solves the problem in the prior art where insufficient pressure reduction capacity during cable formation testing leads to a small pressure wave influence range and inaccurate permeability results. Furthermore, a fluid isolation system restricts the sealed casing within the test section of the test well and prevents external fluids from entering the test section, thus avoiding the influence of hydrate decomposition and drilling mud skin on the formation pressure response during testing. Attached Figure Description

[0034] Figure 1 is a schematic diagram of the structure of the present invention.

[0035] Explanation of reference numerals in the attached drawings: 1-Sealed housing; 2-Pressure tank; 3-Piston; 4-Air tank; 5-Motor; 6-Gear transmission device; 7-Wire harness; 8-Controller; 9-Bracket; 10-Pressure balance port; 11-1-First solenoid valve; 11-2-First solenoid valve; 11-3-First solenoid valve; 12-1-First pressure sensor; 12-2-Second pressure sensor; 13-Filter screen; 14-Rubber tire; 15-First connector; 16-Second connector; 17-Drive shaft; 18-Screw. Detailed implementation method:

[0036] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.

[0037] As shown in Figure 1, a hydrate downhole permeability monitoring device includes a sealed housing 1, a pressure system, a fluid isolation system, a control and data processing system, a detection system, and multiple valve bodies;

[0038] The control and data processing system is connected to the pressure system, fluid isolation system, detection system, and multiple valve bodies, respectively.

[0039] The control and data processing system is used to control the start and stop of pressure systems, fluid isolation systems and detection systems, as well as to control the opening and closing of multiple valves;

[0040] A receiving space that communicates with the outside is formed inside the sealed housing 1;

[0041] The pressure system is located in the accommodating space. The pressure system includes a pressure supply system and a pressure control system. The pressure supply system is used to provide pressure; the pressure control system is used to adjust the pressure within the test section.

[0042] A fluid isolation system is installed on the sealing housing 1. The fluid isolation system is used to restrict the sealing housing 1 within the test section of the test well and to prevent fluids outside the test section from entering the test section.

[0043] The detection system includes multiple pressure sensors, which monitor the pressure value of the pressure system and transmit the pressure value data to the control and data processing system.

[0044] The fluid isolation system confines the sealed housing 1 within the test section. The pressure value within the test section is detected by the detection system, and the pressure value within the test section is adjusted by the pressure system to disturb the pressure within the test section. The pressure change curve is obtained by the pressure change value to calculate the permeability of the hydrate reservoir.

[0045] In detail, this invention employs a pressure perturbation method. When the pressure is restored, a pressure recovery curve is obtained, and the permeability of the hydrate reservoir is then calculated. This solves the problem in the prior art where insufficient pressure reduction capacity during cable stratum testing leads to a small pressure wave influence range and inaccurate permeability results.

[0046] The fluid isolation system restricts the sealing shell 1 within the test section of the test well and prevents fluids outside the test section from entering it, thus avoiding the formation pressure response from being easily affected by hydrate decomposition and drilling mud during testing.

[0047] In some embodiments of the present invention, the pressure supply system includes a pressure source, which is a pressure device filled with fluid, and the pressure device is disposed in the accommodating space.

[0048] Both the sealing housing 1 and the pressure device are provided with multiple openings, including a pressure balance port 10, a fluid inlet and outlet and a first through hole;

[0049] The pressure balance port 10 and fluid inlet / outlet on the sealing housing 1 and the pressure balance port 10 and fluid inlet / outlet on the pressure device are respectively provided and connected through a fluid channel; the first through hole on the sealing housing 1 is the outlet of the wire harness 7 and the first through hole on the pressure device is the through hole of the piston 3.

[0050] Since hydrates are abundant in a low-temperature and high-pressure environment, the sealing shell 1 is not made of a material resistant to low-temperature and high-pressure conditions. The sealing shell 1 is used to protect the various devices inside and prevent the infiltration of pore fluids, and its airtightness is required to be high.

[0051] In this embodiment, the pressure supply system includes a pressure source that provides pressure to the test section. The pressure source is a pressure vessel containing fluid; in this invention, pressure vessel 2 is used as an example. Pressure vessel 2 is detachably mounted on a sealing housing 1. Both the sealing housing 1 and pressure vessel 2 include four openings: a pressure balance port 10, a fluid inlet, a pressure outlet, and a first through hole. The corresponding pressure balance port 10, fluid inlet, and pressure outlet are connected via fluid channels.

[0052] Furthermore, filters 13 are provided on both the fluid inlet and the fluid outlet on the sealed housing 1. The filters 13 are used to prevent mud, sand and other debris in the test well from entering the pressure tank 2.

[0053] Furthermore, the pressure control system includes a pressure reduction system mounted on the pressure supply system via a bracket 9, which can reduce the pressure in the test section.

[0054] The pressure inside pressure tank 2 is reduced to achieve a pressure disturbance effect. Furthermore, a pressure sensor is installed inside pressure tank 2 to obtain the pressure value in real time, thus achieving pressure monitoring. It should be noted that, due to the need for real-time pressure monitoring, the pressure tank 2 must be kept airtight.

[0055] In detail, the pressure reduction system includes a drive device, a transmission device, and a piston 3; wherein, the piston 3 is disposed in the pressure device, and the piston rod 19 passes through the through hole of the piston 3; the drive device drives the piston rod 19 of the piston 3 to move up and down along the axis of the pressure device through the transmission device; when the piston rod 19 moves upward, it reduces the pressure inside the pressure device, making the pressure lower than the formation pressure; when the piston rod 19 moves downward, it discharges the fluid that has entered the pressure device.

[0056] During pressure reduction, power is provided by the drive device and transmitted through the transmission device, so that the piston 3 moves up and down along the axis of the pressure tank 2. When the piston 3 moves upward, the pressure in the pressure tank 2 is reduced to be lower than the bottom pressure. When the piston 3 moves downward, the pressure in the pressure tank 2 is discharged. Here, the pressure is the fluid that entered the pressure tank 2 during the pressure recovery phase. Moreover, during the discharge process, the fluid is discharged through the fluid outlet. Under the action of the fluid, the filter screen 13 is cleaned.

[0057] In a specific embodiment of this method, the driving device is a motor 5, and the transmission device is a gear transmission device 6. The gear transmission device 6 includes a first connecting member 15 and a second connecting member 16, with the second connecting member 16 fixed to the first connecting member 15. The drive shaft 17 of the motor 5 is connected to the second connecting member 16. A screw 18 is connected to the outer side of the first connecting member 15, and a piston rod 19 passes through the first connecting member 15 and the second connecting member 16. When the drive shaft 17 of the motor 5 rotates, it drives the first connecting member 15 and the second connecting member 16 to move on the piston rod 19, and simultaneously drives the first connecting member 15 and the second connecting member 16 to move on the screw 18. Preferably, the drive shaft 17 can also be a screw.

[0058] In some embodiments of the present invention, the control and data processing system includes a controller 8 and a data center connected via a wiring harness 7. The data center is located outside the test well, and the controller 8 is detachably installed in the accommodating space. The wiring harness 7 passes through its outlet and connects the controller 8 and the control center. The controller 8 is detachably installed within the sealed housing 1, while the data center can be located outside the test well for operation by testing personnel. The controller 8 can send and receive signals, directly controlling the opening and closing of each valve and the start and stop of the drive device, and collecting pressure data from multiple pressure sensors in the detection system, uploading it to the data center via the wiring harness 7. The data center can store and visualize the measured pressure change data, and can calculate the permeability of the test section using a pre-defined mathematical model. Testing personnel can issue commands from the data center to perform related operations.

[0059] In some embodiments of the present invention, the fluid isolation system includes a gas storage tank 4 and a rubber tire 14 connected by a gas channel; a valve body is provided on the gas channel, and both the gas storage tank 4 and the valve body are connected to a control and data processing system to control the air intake of the gas channel; the gas storage tank 4 is detachably disposed in the accommodating space, and the rubber tire 14 is disposed at both ends of the sealing housing 1.

[0060] The gas storage tank 4 is filled with gas, which inflates the rubber tire 14. When the rubber tire 14 is inflated, the sealing shell 1 can be fixed in a certain test section of the test well and the fluid outside the test section can be isolated from entering the test section. This avoids the formation pressure response being easily affected by hydrate decomposition and drilling mud during the test.

[0061] Furthermore, both ends of the sealing housing 1 are provided with arc-shaped grooves to fix the rubber tire 14 in the arc-shaped grooves.

[0062] In some embodiments of the present invention, multiple pressure sensors are installed on the pressure apparatus of the pressure system and / or the gas storage tank 4 of the fluid isolation system to obtain pressure value data of the pressure tank 2 and / or the gas storage tank 4. The pressure sensors are used to convert pressure signals into electrical signals.

[0063] In some embodiments of the present invention, multiple valve bodies are detachably mounted on a fluid passage and / or a gas passage for controlling the opening and closing of the fluid passage and / or gas passage. All valve bodies are solenoid valves and can be controlled by a control and data processing system.

[0064] As a specific embodiment of the present invention, the present invention achieves the effect of pressure disturbance by setting a pressure system in the test section. Since the pressure tank 2 has a large capacity and its initial low pressure can be adjusted as needed, the connected reservoir can generate a large pressure disturbance, effectively overcoming the shortcomings of the limited detection range of existing cable formation testing methods.

[0065] Existing formation testing methods measure the pressure response as the formation pressure itself, which is easily affected by hydrate decomposition and drilling fluid mud. This invention, however, measures the pressure response within the pressure tank 2, and with the filtration effect of the filter screen 13, minimizes the influence of drilling fluid mud. Furthermore, by controlling formation pressure fluctuations, it is possible to maintain formation pressure above the hydrate phase equilibrium pressure to prevent hydrate decomposition from interfering with monitoring results; conversely, it is also possible to maintain formation pressure below the hydrate phase equilibrium pressure to investigate the specific impact of hydrate decomposition on monitoring results and elucidate its mechanism.

[0066] In a specific embodiment of the present invention, multiple valve bodies are connected to the controller 8. The multiple valve bodies include a first solenoid valve 11-1, a second solenoid valve 11-2, and a third solenoid valve 11-3. The first solenoid valve 11-1 and the second solenoid valve 11-2 are disposed on the fluid channel connecting two fluid inlets and outlets. Specifically, the first solenoid valve 11-1 is disposed on the fluid channel connecting two fluid inlets, the second solenoid valve 11-2 is disposed on the fluid channel connecting two fluid outlets, and the third solenoid valve 11-3 is disposed on the gas channel connecting the gas storage tank 4 and the rubber tire 14.

[0067] Multiple pressure sensors are connected to the controller 8. The multiple pressure sensors include a first pressure sensor 12-1 and a second pressure sensor 12-2. The first pressure sensor 12-1 is installed on the gas storage tank 4, and the second pressure sensor 12-2 is installed on the pressure tank 2.

[0068] This invention is installed in a test section of the test well through a fluid isolation system, which is enclosed by pore fluid; the main data center is generally located outside the test well.

[0069] The specific working steps of this invention are as follows:

[0070] a. Assemble the present invention and test its airtightness.

[0071] b. Power on and perform a self-test to confirm that all components of the invention are working properly; turn off the power to the drive device and initially set each solenoid valve to the closed state.

[0072] c. Place the present invention in the designated test section of the test well, open the third solenoid valve 11-3 of the gas channel to allow the rubber tire 14 to expand, thereby restricting and fixing the sealing housing 1 in the test section and preventing fluids outside the test section of the test well from entering the test section. Close the third solenoid valve 11-3 of the gas channel.

[0073] d. Turn on the power to motor 5, control motor 5 to make piston 3 move upward, and reduce the pressure in pressure tank 2.

[0074] When the pressure inside pressure tank 2 is lower than the reservoir pore pressure by a certain value, piston 3 reaches the upper limit position, opens the first solenoid valve 11-1 of the fluid inlet, and the reservoir pore fluid enters the pressure tank 2. The second pressure sensor 12-2 records the pressure change data. When the pressure and pore pressure are consistent, the first solenoid valve 11-1 of the fluid inlet is closed, the pressure data is uploaded to the central data center, and then the permeability is calculated based on the pressure recovery data.

[0075] e. Open the first solenoid valve 11-1 at the fluid inlet and the second solenoid valve 11-2 at the fluid outlet, control the motor 5, drive the piston 3 to move downward, discharge the pore fluid from the pressure tank 2, and at the same time clean the filter screen 13.

[0076] f. When piston 3 reaches the lower limit, turn off the power to motor 5, and close the first solenoid valve 11-1 at the fluid inlet and the second solenoid valve 11-2 at the fluid outlet.

[0077] Repeat the above steps for the next test.

[0078] After the test is completed, open the first solenoid valve 11-1 of the gas channel to deflate the rubber tire 14, so that it is no longer in close contact with the test well wall; then the device can be pulled out of the test well for recovery by a cable.

[0079] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

Claims

1. A hydrate downhole permeability monitoring device, characterized in that, It includes a sealed housing, a pressure system, a fluid isolation system, a control and data processing system, a detection system, and multiple valve bodies; The control and data processing system is connected to the pressure system, the fluid isolation system, the detection system, and the plurality of valve bodies, respectively. The control and data processing system is used to control the start and stop of the pressure system, the fluid isolation system and the detection system, as well as to control the opening and closing of the plurality of valve bodies; The sealed housing forms an accommodating space that communicates with the outside world; The pressure system is disposed in the accommodating space. The pressure system includes a pressure supply system and a pressure control system. The pressure supply system is used to provide pressure. The pressure control system is used to adjust the pressure within the test section. The fluid isolation system is disposed on the sealing housing. The fluid isolation system is used to restrict the sealing housing within the test section of the test well and to prevent fluids outside the test section from entering the test section. The detection system includes multiple pressure sensors, which are used to monitor the pressure value of the pressure system and transmit the pressure value data to the control and data processing system. The fluid isolation system confines the sealed housing within the test section. The detection system detects the pressure value within the test section. The pressure system adjusts the pressure value within the test section to disturb the pressure. By analyzing the pressure changes, a pressure change curve is obtained to calculate the hydrate reservoir permeability.

2. The hydrate downhole permeability monitoring device of claim 1, wherein, The pressure supply system includes a pressure source, which is a pressure device loaded with fluid, and the pressure device is disposed in the accommodating space; Both the sealing housing and the pressure device are provided with multiple openings, including a pressure balance port, a fluid inlet and outlet, and a first through hole; wherein the fluid inlet and outlet include a fluid inlet and a fluid outlet. The pressure balance port and fluid inlet / outlet on the sealing housing and the pressure balance port and fluid inlet / outlet on the pressure device are respectively provided and connected by fluid pipes; the first through hole on the sealing housing is the wire harness outlet and the first through hole on the pressure device is the piston through hole.

3. The hydrate downhole permeability monitoring device of claim 2, wherein, The pressure control system includes a pressure reduction system mounted on the pressure supply system via a bracket. The pressure reduction system includes a drive device, a transmission device, and a piston; wherein the piston is disposed in the pressure appliance, and the piston rod passes through the piston through hole; The driving device drives the piston rod of the piston to move up and down along the axis of the pressure device through the transmission device; When the piston rod moves upward, it reduces the pressure inside the pressure device, making the pressure lower than the formation pressure; when the piston rod moves downward, it discharges the fluid that entered the pressure device.

4. The hydrate downhole permeability monitoring device of claim 3, wherein, The driving device is an electric motor, and the transmission device is a gear transmission device; The gear transmission device includes a first connecting member and a second connecting member, the second connecting member being fixed on the first connecting member; the drive shaft of the motor is connected to the second connecting member, a screw is connected to the outside of the first connecting member, and the piston rod passes through the first connecting member and the second connecting member; When the drive shaft of the motor rotates, it drives the first connecting member and the second connecting member to move on the piston rod, and at the same time drives the first connecting member and the second connecting member to move on the screw.

5. The hydrate downhole permeability monitoring device of claim 2, wherein, The control and data processing system includes a controller and a data center connected by a wiring harness. The data center is located outside the test well, and the controller is detachably installed in the accommodating space. The wiring harness passes through the wiring harness outlet and connects the controller and the control center.

6. The hydrate downhole permeability monitoring device of claim 2, wherein, Filter screens are provided on the fluid inlet and outlet of the sealed housing.

7. The hydrate downhole permeability monitoring device of claim 1, wherein, The fluid isolation system includes a gas storage tank and a rubber tire connected by a gas pipeline; A valve body is installed on the gas pipeline, and both the gas storage tank and the valve body are connected to the control and data processing system to control the gas intake of the gas pipeline; The gas storage tank is detachably installed in the accommodating space, and the rubber tire is installed at both ends of the sealed housing.

8. The hydrate downhole permeability monitoring device of claim 1, wherein, All of the valve bodies are solenoid valves.

9. The hydrate downhole permeability monitoring device of claim 1, wherein, Multiple pressure sensors are mounted on the pressure apparatus of the pressure system and / or the gas storage tank of the fluid isolation system.

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