Device and method for testing liquid or gas production profile of undersaturated gas reservoir

Abstract

The invention discloses an under-saturated gas reservoir liquid production or gas production profile testing device and method, and belongs to the technical field of gas production. The under-saturated gas reservoir liquid production or gas production profile testing device comprises an original well casing, and a testing mechanism is arranged in the original well casing; the testing mechanism comprises an oil pipe, a screen pipe is coaxially and fixedly arranged at the end, away from a wellhead, of the oil pipe, a gas anchor is arranged at the end, close to the screen pipe, in the oil pipe, and a packer is arranged at the end, away from the gas anchor, of the screen pipe. A water suction pump is arranged in the oil pipe and connected with a steel wire rope winding mechanism on the ground through a steel wire rope. A testing system capable of monitoring temperature and pressure in real time is arranged on the outer wall, close to the gas anchor, of the oil pipe. The water suction pump is arranged and can replace an underground power system pulled out of an original well, so that the actual output conditions, including the liquid production capacity and the gas production capacity corresponding to each perforation section, of each perforation section are tested, the production dynamic state of each production layer section is determined, and effective data support for judging the liquid production or gas production section is formed; the testing device is simple, the cost is low, and the testing method is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas production, and particularly relates to a liquid or gas profile testing device and a testing method for an undersaturated gas reservoir. Background Art

[0002] Unconventional oil and gas (such as shale gas, coalbed methane, etc.) underpressure reservoirs often adopt the process technologies of vertical well multi-layer combined production or horizontal well segmented fracturing multi-segment combined production. Among them, the identification of the main gas supply layers in vertical well multi-layer combined production, the evaluation of the fracturing transformation effect of each section of the horizontal well, and the solution of bottleneck problems such as low gas well productivity caused by difficult reservoir pressure reduction due to the communication between some sections and aquifers during the drainage process all rely on the accurate testing of the liquid or gas profile of the underpressure reservoir. In order to find the main water-producing layers, provide references for fracturing layer selection and optimization of fracturing process parameters in the development stage, and then take targeted water shutoff measures for abnormal water-producing sections to maximize the single-well productivity. For the testing of the liquid or gas profile, first, the liquid production and gas production corresponding to each section need to be obtained, and then the production dynamics of each production section are determined to form effective data support for judging the liquid or gas profile. Therefore, the current traditional testing processes for liquid or gas profile are all used to measure the liquid production and gas production of each production section.

[0003] The traditional liquid profile testing process technology has poor adaptability to unconventional oil and gas underpressure reservoirs, and mainly has the following deficiencies: for unconventional oil and gas underpressure reservoirs, before the production profile testing tools and instruments enter the well, the downhole power system needs to be removed, and the formation produced fluid cannot flow by self-jetting, so the actual production situation of each section cannot be tested; the traditional liquid profile testing device requires a large number of supporting equipment, with high costs and great implementation difficulties. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned deficiencies of the prior art and provide a liquid or gas profile testing device for an undersaturated gas reservoir.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A liquid or gas profile testing device for an undersaturated gas reservoir, including a production casing, and a testing mechanism is arranged inside the production casing;

[0007] The testing mechanism includes a tubing string, a screen pipe is coaxially and fixedly arranged at one end of the tubing string away from the wellhead, a gas anchor is arranged at one end of the tubing string close to the screen pipe, and a packer is arranged at one end of the screen pipe away from the gas anchor;

[0008] A submersible pump is arranged inside the tubing string, and the submersible pump is connected to a wire rope winding mechanism on the ground through a wire rope;

[0009] A testing system capable of real-time monitoring of temperature and pressure is arranged on the outer wall of the tubing string close to the gas anchor.

[0010] The present invention also provides a method for testing the liquid or gas production profile of an undersaturated gas reservoir.

[0011] A method for testing the liquid or gas production profile of an undersaturated gas reservoir is implemented based on a testing device for the liquid or gas production profile of an undersaturated gas reservoir. The testing method includes the following steps:

[0012] Step 1: Pull out the original well string, then conduct hole cleaning. After confirming that the entire wellbore is unobstructed, lower the testing mechanism to the bottom of the well so that the packer is located between the first perforation interval and the second perforation interval.

[0013] Step 2: Consult the original production report to obtain the actual daily flowing pressure drop ΔP0 and the daily liquid production W0 of the original well before testing.

[0014] Step 3: Determine the value a of the one-way moving distance of the submersible pump and the value b of the up-and-down frequency.

[0015] Step 4: Drag the tubing to make the packer located between each perforation interval in turn, conduct a pumping test for a time t, and obtain the gas production, liquid production of the formation during pumping when the packer is located between each perforation interval, as well as the changes in the pressure values and temperature values measured by the testing system before and after each pumping.

[0016] Step 5: Calculate the cumulative liquid production and cumulative gas production of each perforation interval within the time t.

[0017] Preferably, the step 3 includes the following sub-steps:

[0018] Step 31: Convert the daily liquid production:

[0019]

[0020] In the formula, D is the inner diameter of the tubing, s is the one-way moving distance, n is the up-and-down frequency, and k is the pump efficiency;

[0021] Step 32: Let j = 0, and n0 is 2 - 3;

[0022] Step 33: Set the value of n as n j , k = 0.8, and obtain the value s of the one-way moving distance j ;

[0023]

[0024] Step 34: Determine the setting depth h1 of the submersible pump;

[0025] h1 = H1 - P 当前 ×100 + s j +20 (3)

[0026] Wherein, H1 is the running-in depth of the testing system when the packer is located between the first perforation section and the second perforation section, and P 当前 is the pressure value measured by the testing system at the current moment, with the unit of MPa. Multiply P 当前 by 100 to convert the pressure value into the water column height;

[0027] Adjust the running-in depth of the water pump to h1;

[0028] Step 35: With the one-way moving distance being sj and the up-and-down frequency being n j Start the water pump. The running time of the water pump is t, and measure the change ΔP in the pressure value measured by the testing system before and after this pumping w ;

[0029] Step 36: When make n j+1 = n j (1 + 20%), and enter Step 37;

[0030] When make n j+1 = n j (1 - 20%), and enter Step 37;

[0031] where ε is the error setting value, which is greater than 0;

[0032] Otherwise, enter Step 38;

[0033] Step 37: Let j = j + 1, and enter Step 33;

[0034] Step 38: a = s j and b = n j .

[0035] Preferably, Step 4 includes the following sub-steps:

[0036] Step 41: Let i = 1;

[0037] Step 42: Start the water pump with the one-way moving distance being a and the up-and-down frequency being b. The running time of the water pump is t, and record the gas production Q0, liquid production W0 of the formation during the corresponding pumping period when the packer is not set and located between the first perforation section and the second perforation section, as well as the change ΔP0 in the pressure value measured by the testing system before and after this pumping and the change ΔT0 in the measured temperature value;

[0038] Step 43: Start the water pump with the one-way moving distance being a and the up-and-down frequency being b. The running time of the water pump is t, and record the gas production Q i and liquid production W iAnd the change Δ in the pressure value measured by the test system before and after this pumping i , the change ΔT in the measured temperature value i ;

[0039] Step 44, let i = i + 1;

[0040] Step 45, drag the tubing upward to make the packer seal between the i-th perforation interval and the (i + 1)-th perforation interval, and record the pressure value P measured by the test system at the current moment 当前 ;

[0041] Determine the lowering depth h of the water pump when the packer seals between the i-th perforation interval and the (i + 1)-th perforation interval i ;

[0042] h i = H i - P 当前 ×100 + a + 20 (4)

[0043] In the formula, H i is the lowering depth of the test system when the packer is between the i-th perforation interval and the (i + 1)-th perforation interval, P 当前 is the pressure value measured by the test system at the current moment, with the unit of MPa, P 当前 ×100 converts the pressure value into the water column height;

[0044] Adjust the lowering depth of the water pump to h i ;

[0045] Then enter Step 43.

[0046] Preferably, in Step 5, the serial number of the perforation interval farthest from the bottom of the well is N, and the calculation formulas for the cumulative liquid production volume and cumulative gas production volume of the i-th perforation interval within time t are as follows:

[0047] N i = Q0 - Q1 (i = 1) (5)

[0048] N i = Q i-1 - Q i (1 < i < N) (6)

[0049] N i = Q i-1 (i = N) (7)

[0050] M i = W0 - W1 (i = 1) (8)

[0051] M i = W i-1 - W i (1 < i < N) (9)

[0052] M i = W i-1 (i = N)(10)

[0053] In the formula, N i is the cumulative gas production of the i-th perforation interval within time t, Q i is the gas production during the corresponding pumping period when the packer is located between the i-th and the (i + 1)-th perforation intervals, Q i-1 is the gas production during the corresponding pumping period when the packer is located between the (i - 1)-th and the i-th perforation intervals; M i is the cumulative liquid production of the i-th perforation interval within time t, W i is the liquid production during the corresponding pumping period when the packer is located between the i-th and the (i + 1)-th perforation intervals, W i-1 is the liquid production during the corresponding pumping period when the packer is located between the (i - 1)-th and the i-th perforation intervals.

[0054] Preferably, t is 0.5 hour.

[0055] The beneficial effects of the present invention are as follows:

[0056] The present invention provides a submersible pump, which can replace the downhole power system removed from the original well, so as to test the actual production conditions of each perforation interval, including the liquid production and gas production corresponding to each perforation interval, and further determine the production dynamics of each production interval, forming an effective data support for judging the liquid or gas production profile; the testing device of the present invention is simple, low in cost, and the testing method is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The specification drawings forming a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application.

[0058] Figure 1 is a schematic structural diagram of the liquid or gas production profile testing device for an undersaturated gas reservoir of the present invention when located in a horizontal well;

[0059] Figure 2 is a schematic structural diagram of the liquid or gas production profile testing device for an undersaturated gas reservoir of the present invention when located in a vertical well;

[0060] Wherein:

[0061] 1 - First perforation interval, 2 - Packer, 3 - Screen pipe, 4 - Gas anchor, 5 - Testing system, 6 - Oil pipe, 7 - Submersible pump, 8 - Steel wire rope, 9 - Steel wire rope winding mechanism, 10 - Casing, 11 - Second perforation interval, 12 - Third perforation interval. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0063] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0064] In the present invention, terms such as "upper", "lower", "bottom", "top", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relational terms determined for facilitating the description of the structural relationship of each component or element of the present invention and do not specifically refer to any component or element in the present invention and should not be construed as a limitation to the present invention.

[0065] In the present invention, terms such as "connected" and "coupled" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances and should not be construed as a limitation to the present invention.

[0066] The present invention will be further described below with reference to the drawings and embodiments.

[0067] Embodiment 1:

[0068] As Figure 1 or Figure 2 shown, a test device for the liquid or gas production profile of an undersaturated gas reservoir includes a production casing 10, and a test mechanism is arranged inside the production casing 10;

[0069] The test mechanism includes a tubing 6. One end of the tubing 6 far from the wellhead is coaxially and fixedly provided with a screen pipe 3. One end of the tubing 6 close to the screen pipe 3 is provided with a gas anchor 4. One end of the screen pipe 3 far from the gas anchor 4 is provided with a packer 2;

[0070] A submersible pump 7 is arranged inside the tubing 6. The submersible pump 7 is connected to a wire rope winding mechanism 9 on the ground through a wire rope 8;

[0071] A test system 5 capable of real-time monitoring of temperature and pressure is arranged on the outer wall of the tubing 6 close to the gas anchor 4.

[0072] Among them, when the liquid or gas profile testing device for an undersaturated gas reservoir in this application is located in a horizontal well, as Figure 1 shown, when the liquid or gas profile testing device for an undersaturated gas reservoir in this application is located in a vertical shaft, as Figure 2 shown.

[0073] Example 2:

[0074] An undersaturated gas reservoir liquid or gas profile testing method is implemented based on the undersaturated gas reservoir liquid or gas profile testing device in Example 1. The testing method includes the following steps:

[0075] Step 1: Pull out the original well string, then conduct hole cleaning. After confirming that the entire wellbore is unobstructed, lower the testing mechanism to the bottom of the well so that the packer 2 is located between the first perforation section 1 and the second perforation section 11. In this application, i is used to represent the serial number of the perforation section. When i = 1, it represents the first perforation section 1; when i = 2, it represents the second perforation section 11, and so on. Among them, the first perforation section 1 is close to the bottom of the well.

[0076] Step 2: Consult the original production report to obtain the actual daily flowing pressure drop ΔP0 and the daily liquid production W0 of the original well before testing.

[0077] Step 3: Determine the value a of the one-way moving distance of the submersible pump 7 and the value b of the up-and-down frequency.

[0078] Specifically, Step 3 includes the following sub-steps:

[0079] Step 31: Convert the daily liquid production:

[0080]

[0081] In the formula, D is the inner diameter of the tubing 6, s is the one-way moving distance, n is the up-and-down frequency, and k is the pump efficiency;

[0082] Step 32: Let j = 0, n0 is 2 - 3, and n0 is the initial value of the up-and-down frequency.

[0083] Step 33: Set the value of n as n j , k = 0.8, and obtain the value s of the one-way moving distance j ;

[0084]

[0085] Step 34: Determine the setting depth h1 of the submersible pump 7;

[0086] h1 = H1 - P 当前 ×100 + s j +20 (3)

[0087] Wherein, H1 is the running-in depth of the testing system 5 when the packer 2 is located between the first perforation section 1 and the second perforation section 11, P 当前 is the pressure value measured by the testing system 5 at the current moment, with the unit of MPa, P 当前 is multiplied by 100 to convert the pressure value into the water column height;

[0088] Adjust the running-in depth of the water pump 7 to h1;

[0089] Step 35, with the one-way moving distance being s j and the up-and-down frequency being n j Start the water pump 7, the running time of the water pump 7 is t, with the unit of hour, and measure the change ΔP in the pressure value measured by the testing system 5 before and after this pumping w ;

[0090] Step 36, when , let n j+1 = n j (1 + 20%), and enter Step 37;

[0091] When , let n j+1 = n j (1 - 20%), and enter Step 37;

[0092] where ε is the error setting value, which is greater than 0;

[0093] Otherwise, enter Step 38;

[0094] Step 37, let j = j + 1, and enter Step 33;

[0095] Step 38, a = s j , b = n j .

[0096] Step 4, by dragging the tubing 6, make the packer 2 located between each perforation section in turn, conduct a pumping test for time t, and obtain the gas production, liquid production of the formation during pumping when the packer 2 is located between each perforation section, as well as the changes in the pressure value and the measured temperature value measured by the testing system 5 before and after each pumping.

[0097] Specifically, the said Step 4 includes the following sub-steps:

[0098] Step 41, let i = 1;

[0099] Step 42: Start the water pump 7 with a one-way moving distance of a and a lifting and lowering frequency of b. The running time of the water pump 7 is t. Record the formation gas production Q0, liquid production W0 during the pumping period when the packer 2 is not set between the first perforation section 1 and the second perforation section 11, and the change ΔP0 in the pressure value measured by the test system 5 and the change ΔT0 in the measured temperature value before and after this pumping.

[0100] Step 43: Start the water pump 7 with a one-way moving distance of a and a lifting and lowering frequency of b. The running time of the water pump 7 is t. Record the formation gas production Q i , liquid production W i and the change ΔP i in the pressure value measured by the test system 5 and the change ΔT i in the measured temperature value before and after this pumping when the packer 2 is set between the i-th perforation section and the (i + 1)-th perforation section;

[0101] Step 44: Let i = i + 1;

[0102] Step 45: Drag the tubing 6 upward to set the packer 2 between the i-th perforation section and the (i + 1)-th perforation section, and record the pressure value P 当前 measured by the test system 5 at the current moment;

[0103] Determine the setting depth h i of the water pump 7 when the packer 2 is set between the i-th perforation section and the (i + 1)-th perforation section;

[0104] h i = H i - P 当前 × 100 + a + 20 (4)

[0105] In the formula, H i is the setting depth of the test system 5 when the packer 2 is between the i-th perforation section and the (i + 1)-th perforation section, P 当前 is the pressure value measured by the test system 5 at the current moment, with the unit of MPa. P 当前 × 100 converts the pressure value to the water column height;

[0106] Adjust the setting depth of the water pump 7 to h i ;

[0107] Then enter Step 43.

[0108] Step 5: Calculate the cumulative liquid production and cumulative gas production of each perforation section within the time t.

[0109] Specifically, in the said Step 5, the serial number of the perforation section farthest from the bottom of the well is N. The calculation formulas for the cumulative liquid production and cumulative gas production of the i-th perforation section within the time t are as follows:

[0110] N i = Q0 - Q1 (i = 1) (5)

[0111] N i = Q i-1 - Q i (1 < i < N) (6)

[0112] N i = Q i-1 (i = N) (7)

[0113] M i = W0 - W1 (i = 1) (8)

[0114] M i = W i-1 - W i (1 < i < N) (9)

[0115] M i = W i-1 (i = N) (10)

[0116] Wherein, N i is the cumulative gas production of the i-th perforation interval within time t, Q i is the gas production during the corresponding pumping period when the packer 2 is located between the i-th perforation interval and the (i + 1)-th perforation interval, Q i-1 is the gas production during the corresponding pumping period when the packer 2 is located between the (i - 1)-th perforation interval and the i-th perforation interval; M i is the cumulative liquid production of the i-th perforation interval within time t, W i is the liquid production during the corresponding pumping period when the packer 2 is located between the i-th perforation interval and the (i + 1)-th perforation interval, W i-1 is the liquid production during the corresponding pumping period when the packer 2 is located between the (i - 1)-th perforation interval and the i-th perforation interval.

[0117] Specifically, t is 0.5 hour.

[0118] The present invention is provided with a water pump, which can replace the downhole power system removed from the original well, so as to test the actual production conditions of each perforation interval, including the liquid production and gas production corresponding to each perforation interval, and further determine the production dynamics of each production interval, forming an effective data support for judging the liquid or gas profile; in addition, the present invention also obtains the changes in the pressure values and temperature values measured by the test system 5 before and after pumping when the packer 2 is located in the corresponding interval, which can provide data support for analyzing the gas or liquid supply capacity of the formation; the test device of the present invention is simple and low in cost, and the test method is simple.

[0119] Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, it is not a limitation of the present invention. Those skilled in the art should understand that various modifications or variations that can be made without creative efforts on the basis of the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A device for testing liquid production or gas profile of an undersaturated gas reservoir, comprising an original well casing, wherein a testing mechanism is arranged in the original well casing; characterized in that: The testing mechanism comprises an oil pipe, a screen is coaxially fixedly arranged at one end of the oil pipe away from the wellhead, an air anchor is arranged at one end of the oil pipe close to the screen, and a packer is arranged at one end of the screen away from the air anchor; A water pump is arranged in the oil pipe, and the water pump is connected to a wire rope winding mechanism on the ground through a wire rope; A testing system capable of real-time monitoring of temperature and pressure is arranged on the outer wall of the oil pipe close to the air anchor.

2. A method for testing liquid production or gas profile of an undersaturated gas reservoir, implemented based on the device for testing liquid production or gas profile of an undersaturated gas reservoir as claimed in claim 1, characterized in that: The test method comprises the following steps: Step 1: pull out the original well string, then clear the well, confirm that the entire wellbore is unobstructed, and then lower the testing mechanism to the bottom of the well so that the packer is located between the first perforation section and the second perforation section; Step 2, check the original production report to obtain the actual daily flow pressure drop ΔP0 and daily liquid production W0 of the original well before the test; Step 3, determining the value a of the one-way moving distance of the water pump and the value b of the lifting and lowering frequency; Step 4, by dragging the tubing, the packer is positioned between each perforation section in turn, and a pumping test is performed for a time t, to obtain the formation gas production and liquid production during the pumping period when the packer is positioned between each perforation section, as well as the changes in the pressure value and the temperature value tested by the test system before and after each pumping; Step 5: Calculate and obtain the cumulative liquid production and cumulative gas production of each perforation section within time t.

3. The method for testing liquid production or gas profile of an undersaturated gas reservoir according to claim 2, characterized in that: The step 3 includes the following sub-steps: Step 31, convert daily liquid production: In the formula, D is the inner diameter of the oil pipe, s is the one-way moving distance, n is the lifting and lowering frequency, and k is the pump efficiency; Step 32, let j=0, n0 be 2-3; Step 33, set the value of n to n j , k = 0.8, and the value of the one-way moving distance is obtained as s j ; Step 34, determining the lowering depth h1 of the water pump; h1=H1-P 当前 ×100+s j +20 (3) Where H1 is the depth of the test system when the packer is located between the first perforation section and the second perforation section, P 当前 It is the pressure value tested by the test system at the current moment, in MPa, P 当前 ×100 converts the pressure value into water column height; Adjust the lowering depth of the water pump to h1; Step 35, take the one-way moving distance as s j , the lifting and lowering frequency is n j Start the pump, the pump runs for t, and measure the change ΔP of the pressure value tested by the test system before and after the pumping. w ; Step 36, when When n j+1 =n j (1+20%), go to step 37; when When n j+1 =n j (1-20%), go to step 37; Where ε is the error setting value, which is greater than 0; Otherwise, proceed to step 38; Step 37, let j=j+1, and go to step 33; Step 38, a=s j , b=n j .

4. The method for testing liquid production or gas profile of an undersaturated gas reservoir according to claim 3, characterized in that: The step 4 includes the following sub-steps: Step 41, let i=1; Step 42, start the pumping pump with a one-way moving distance of a and a lifting and lowering frequency of b, and the pumping pump running time is t, and record the formation gas production Q0 and liquid production W0 during the corresponding pumping period when the packer is located between the first perforation section and the second perforation section without setting, as well as the change ΔP0 of the pressure value tested by the test system before and after the pumping, and the change ΔT0 of the measured temperature value; Step 43: Start the pump with a one-way moving distance of a and a lifting and lowering frequency of b. The pump running time is t. Record the formation gas production Q during the pumping period when the packer is located between the i-th perforation section and the i+1-th perforation section and is set. i , liquid production W i And the change of pressure value tested by the test system before and after the pumping ΔP i , the change of the measured temperature value ΔT i ; Step 44, let i=i+1; Step 45, drag the tubing upward to set the packer between the i-th perforation section and the i+1-th perforation section, and record the pressure value P tested by the test system at the current moment. 当前 ; Determine the pump's lowering depth h when the packer is set between the i-th perforation section and the i+1-th perforation section i ; h i =H i -P 当前 ×100+a+20 (4) In the formula, H i is the running depth of the test system when the packer is located between the i-th perforation section and the i+1-th perforation section, P 当前 It is the pressure value tested by the test system at the current moment, in MPa, P 当前 ×100 converts the pressure value into water column height; Adjust the lowering depth of the water pump to h i ; Then proceed to step 43.

5. The method for testing liquid production or gas profile of an undersaturated gas reservoir according to claim 4, characterized in that: In step 5, the serial number of the perforation section farthest from the bottom of the well is N, and the calculation formulas for the cumulative liquid production and the cumulative gas production of the i-th perforation section within time t are as follows: N i =Q0-Q1(i=1) (5) N i =Q i-1 -Q i (1<i<N) (6) N i =Q i-1 (i=N) (7) M i =W0-W1(i=1) (8) M i =W i-1 -W i (1<i<N) (9) M i =W i-1 (i=N) (10) Where N i is the cumulative gas production of the i-th perforation section within time t, Q i is the gas production during the pumping period when the packer is located between the i-th perforation section and the i+1-th perforation section, Q i-1 is the gas production during the corresponding pumping period when the packer is located between the i-1th perforation section and the i-th perforation section; M i is the cumulative liquid production of the i-th perforation section in time t, W i is the liquid production during the pumping period when the packer is located between the i-th perforation section and the i+1-th perforation section, W i-1 is the liquid production during the pumping period when the packer is located between the i-1th perforation section and the i-th perforation section.

6. The method for testing liquid production or gas profile of an undersaturated gas reservoir according to claim 3, characterized in that: t is 0.5 hours.

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