Method and device for determining gas well productivity calculation parameters

Abstract

The invention relates to the technical field of gas well exploitation, and discloses a method and device for determining gas well productivity calculation parameters, and the method comprises the following steps: S1, building a relational expression between the gas well test gas production rate and the flow pressure gradient according to the test data of a gas well subjected to productivity well test in a gas reservoir; s2, obtaining a static pressure gradient of the gas well in the gas reservoir based on a relational expression between a gas well test gas production rate and a flow pressure gradient, and then determining a to-be-developed productivity to calculate a middle formation pressure of a production layer of the gas well; s3, the test yield of the gas well is calculated according to the capacity to be developed, the flow pressure gradient of the well is obtained, and then the middle flow pressure of a production layer of the well is calculated; and S4, establishing a binomial productivity equation according to the test data of the gas well subjected to productivity well testing in the gas reservoir, and finally determining a productivity correction coefficient. According to the method, the calculation work of the other gas well productivity calculation parameters in the gas reservoir area can be carried out only by carrying out productivity well testing work once, and the cost and the period of gas well productivity calculation are remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas exploration, in particular to gas well production, more particularly to a method and device for determining gas well productivity calculation parameters. BACKGROUND

[0002] In recent years, with the development of theory and technology, the proportion of deep natural gas reserves discovered is increasing. From 2008 to 2017, deep reserves accounted for 34.8% of the newly added proven geological reserves of natural gas in China. As of the end of 2018, the cumulative proven geological reserves of deep gas fields under development in China reached 332 billion cubic meters, and the deep natural gas production in 2018 reached 428 billion cubic meters, accounting for 30.2% of the total natural gas production in China. These data are only for deep carbonate gas reservoirs, and the proportion of carbonate and clastic rocks is even larger. These gas reservoirs have the common characteristics of diverse reservoir types, complex gas-water relationship, low initial productivity of gas wells, and easy sand production during production.

[0003] In order to obtain high yield, artificial fracturing or acid fracturing technology must be used to improve single well productivity. At the same time of improving gas well productivity, a large amount of acid liquid needs to be injected into the formation. Influenced by factors such as gas reservoir burial depth, test cost, and wellbore multiphase flow, it is difficult to accurately obtain parameters such as bottom hole static pressure and flowing pressure of the gas well, thus posing new challenges for accurate calculation of gas well productivity. Productivity test is the most effective method for accurately calculating gas well productivity (also known as "gas well open flow potential"), which can accurately measure parameters such as bottom hole pressure. However, productivity test has the problems of long test period and high test cost, and if the gas reservoir is deep and acidic, the test cost will be even higher, which makes it difficult for the gas reservoir to carry out a large number of productivity tests. Further, gas wells often produce gas field water during testing, and gas-liquid two-phase pipe flow often occurs in the wellbore. The current gas-liquid two-phase pipe flow pressure drop calculation models for calculating the bottom hole pressure parameters of gas wells mainly include Duns & Ros model, Orkiszewski model, Beggs & Bril model, Beggs & Brill Revised model, Mukherjee & Bril model, Hagedorn-Brown model, Aziz-Govier-Fogarasi model, Gray model, and Ansari model. These methods all have various limitations, resulting in low accuracy of bottom hole pressure calculation. For example, the Aziz-Govier-Fogarasi model is mainly suitable for bubbly flow and slug flow, and the Gray model is mainly suitable for annular-mist flow. However, in the early stage of the wellbore, multiple flow states may coexist, and the flow state may change during production, thus reducing the calculation reliability of the above models to some extent.

[0004] The invention patent with publication number CN111088974A discloses a method for determining the productivity evaluation of low-permeability gas wells by using the current commercial well testing software to interpret the back pressure testing well final shut-in pressure recovery test section, obtaining the relevant parameters of low-permeability gas wells, and then converting the back pressure testing well into a modified isochronal well test for productivity evaluation according to these parameters.

[0005] For example, the invention patent with publication number CN111199010A discloses a method and device for calculating the productivity of gas wells in tight gas reservoirs based on modified isochronal well testing. According to the production and pressure data during the flow period under different working systems of modified isochronal well testing, the gas well productivity equation set at the end of the flow period and the gas well productivity equation set at the end of the pressure recovery period under different working systems are obtained through the pressure drop superposition principle. The two equation sets are combined and simplified to obtain the simplified productivity equation set. The measured pressure data and production data of modified isochronal well testing under different working systems are substituted into the simplified productivity equation set for data fitting to determine the productivity equation coefficients. The productivity equation coefficients are substituted into the binomial productivity equation to realize the calculation of the productivity of gas wells in tight gas reservoirs.

[0006] The essence of the above prior art is still to determine the productivity calculation parameters of new test gas wells through productivity testing, so there are still the problems and deficiencies of high test cost and difficulty in carrying out productivity testing work in large quantities as described in the background art. SUMMARY

[0007] To solve the problems and deficiencies in the prior art, the present application proposes a method and device for determining the productivity calculation parameters of new test gas wells. The method uses a small number of test data for productivity testing to establish a relationship between the test gas production and the flow pressure gradient, accurately calculates the formation pressure and bottom hole flowing pressure parameters of the gas well to be tested for productivity calculation, and uses the binomial productivity equation obtained from productivity testing to solve the gas reservoir productivity correction coefficient. On this basis, the "one-point method" productivity formula is used to calculate the productivity of the gas well, and the accurately calculated open flow capacity provides technical support for the reasonable production scale and the prediction of cumulative gas production of the gas well.

[0008] To achieve the above-mentioned application purposes, the technical solutions of the present application are as follows:

[0009] The present application proposes a method for determining the productivity calculation parameters of gas wells. Since only a small number of gas wells in the gas reservoir can carry out productivity testing, for gas wells that cannot carry out productivity testing, the conventional "one-point method" productivity prediction formula is usually used to calculate the productivity of the gas well (the formula (1) below is the "one-point method" productivity prediction formula). The test gas production parameter q g can be directly measured on the production site, but the productivity correction coefficient a and the middle formation pressure p Rand the middle stream pressure p of the producing layer of the gas well wf The three parameters need to be calculated.

[0010]

[0011] On the basis of not widely carrying out productivity test in the gas reservoir area, the application proposes the productivity correction coefficient a of the gas well which does not carry out productivity test, the middle formation pressure p of the producing layer of the gas well R and the middle stream pressure p of the producing layer of the gas well wf The calculation method of the three parameters mainly includes the following steps:

[0012] (1) Establish the relationship between the gas test production and the stream pressure gradient

[0013] According to the test data of the gas well which has carried out productivity test in the gas reservoir area, the vertical depth data of the downhole pressure gauge, the gas test production of each test system, the stream pressure data of the downhole pressure gauge and the wellhead oil pressure data are obtained, and then the stream pressure gradient corresponding to each system is calculated through the following formula (2):

[0014]

[0015] In the formula: D i represents the stream pressure gradient corresponding to the i-th test system, and the unit is MPa / 100m; p wfi represents the stream pressure corresponding to the i-th test system, and the unit is MPa; p cfi represents the wellhead oil pressure corresponding to the i-th test system, and the unit is MPa; H is the vertical depth of the pressure gauge, and the unit is m;

[0016] According to the test production and the stream pressure gradient corresponding to each test system, the professional drawing software such as Excel, Originlab, Sigmplot and Matlab is used for drawing, and the following relationship between the test production and the stream pressure gradient is established by linear regression:

[0017] D=a·q g +b (3);

[0018] In the formula: q g represents the gas test production, and the unit is 10 4 m 3 / d; D represents the stream pressure gradient, and the unit is MPa / 100m; a and b are constants, and are dimensionless.

[0019] In this invention, the pressure gauge is generally lowered to the bottom of the well using a steel wire traction method. Therefore, the lowering point is the position where the pressure gauge is lowered into the wellbore. Furthermore, the length of the steel wire lowered into the well is the inclined depth of the pressure gauge. If it is a vertical well, the inclined depth is equal to the vertical depth. If it is an inclined well, the vertical depth can be calculated by referring to the inclined depth and vertical depth obtained during well logging.

[0020] In this invention, if multiple wells in a gas reservoir area have undergone production testing, after calculating the test gas production and flow pressure gradient corresponding to each test regime of the gas well according to the above method, the test gas production and flow pressure gradient corresponding to each test regime of each gas well are plotted on a graph for regression to obtain the final relationship between the test gas production and flow pressure gradient.

[0021] (2) Determine the formation pressure in the middle of the producing layer of the gas well for which production calculation is to be carried out.

[0022] For the same gas reservoir, due to the interconnectedness of the reservoir, the static pressure gradient of different gas wells is the same. When the gas production is 0, it means that there is no fluid flow in the wellbore, which is the static pressure gradient. Therefore, when the tested gas production is 0, according to the above formula (3), the static pressure gradient value D0 can be calculated to be equal to the coefficient b. Based on this, according to the formation pressure P in the middle of the producing layer of a certain gas well that has undergone production testing... RC Vertical depth H in the middle of the producing layer C And the middle depth H of the producing layer of the gas well for which production calculations are to be carried out. NC The formation pressure p in the middle of the producing layer of the gas well for which production capacity calculation is to be carried out can be calculated using the following formula (4). RNC ;

[0023]

[0024] In the formula: P RC This indicates the formation pressure in the middle of the producing layer of a gas well that has undergone production testing, expressed in MPa; H C This indicates the vertical depth of the middle of the producing formation in a gas well that has undergone production testing, in meters (m); H NC D0 represents the vertical depth of the middle of the producing formation of the gas well for which production calculations are to be performed, in meters; D0 represents the static pressure gradient, in MPa / 100m; p RNC This indicates the formation pressure in the middle of the producing layer of the gas well for which production calculations are to be carried out, in MPa.

[0025] (3) Determine the mid-flow pressure of the production zone of the gas well for which production calculation is to be carried out.

[0026] During the oil well testing phase, gas production and wellhead oil pressure tests are conducted. Therefore, the test production rate q of the gas well is calculated based on the production capacity to be achieved. gNC Substituting into formula (3), the flowing pressure gradient D of the well can be obtained. NCBased on this, the vertical depth H of the middle of the producing layer of the gas well is calculated according to the production capacity to be carried out. NC and wellhead oil pressure p cfNC The mid-flow pressure p of the producing layer of the gas well for which production capacity calculation is to be carried out can be calculated using the following formula (5). wfNC ;

[0027] p wfNC =0.01H NC ·D NC +p cfNC (5);

[0028] In the formula: p wfNC This indicates the mid-flow pressure of the producing formation of the gas well for which production calculations are to be performed, in MPa and H. NC D represents the vertical depth of the middle of the producing formation of the gas well for which production calculations are to be performed, in meters. NC This represents the flowing pressure gradient of the gas well for which production calculations are to be performed, in MPa / 100m; p cfNC This indicates the wellhead oil pressure of the gas well for which production capacity calculations are to be carried out, in MPa.

[0029] (4) Calculate the value of the capacity correction factor α.

[0030] For gas wells in the gas reservoir area that have undergone production testing, the normalized pressure squared difference corresponding to each testing regime is calculated using formation pressure, test production under each testing regime, and mid-flow pressure in the producing layer. Then draw the binomial production capacity equation diagram (see appendix). Figure 4 The values ​​of coefficients A and B of the binomial production capacity equation are obtained by regression. Based on this, the corresponding binomial production capacity equation is established (see formula (6)). Then, the unobstructed flow rate q of the gas well that has undergone production capacity testing is solved according to formula (6). AOF ;

[0031]

[0032] In the formula: p sc This represents atmospheric pressure, with a value of 0.101, and the unit is MPa.

[0033] It should be noted that when the flowing pressure p in the middle of the gas well producing formation... wf When the pressure is equal to atmospheric pressure, the corresponding test production q of the gas well g =q AOF This refers to testing the gas production volume, also known as the unobstructed flow rate.

[0034] Based on this, the value of the production capacity correction coefficient α is calculated using the following formula (7). If multiple wells have been tested for production capacity in the gas reservoir, the arithmetic mean of the α values ​​calculated for each well can be used to obtain the α value of the gas reservoir. If only one well has been tested for production capacity, the α value of that well is used instead of the α value of the gas reservoir.

[0035]

[0036] According to the test production q of the gas well to be developed, the production of the gas well is calculated gNC And the above four steps calculate the middle formation pressure p of the production layer of the gas well to be developed RNC , the middle flow pressure p of the production layer cfNC And the value of the productivity correction coefficient α, put the four parameters into formula (1), that is, the productivity (gas well open flow capacity) of the gas well without conducting productivity test is calculated.

[0037] Based on the same inventive concept, another aspect of the present application also provides a device for determining gas well productivity calculation parameters. Since the principle of solving the problem of the device is similar to that of the method for determining gas well productivity calculation parameters, the implementation of the device can be referred to the implementation of the method, and the repeated parts will not be described again. The term "unit" or "module" used below can be a combination of software and / or hardware that implements a predetermined function. Although the device described below is preferably implemented in software, hardware, or a combination of software and hardware is also possible and contemplated. Figure 2 The structure diagram of a device for determining gas well productivity calculation parameters provided by an embodiment of the present application is shown in Figure 2 The device can include:

[0038] A gas well test gas production and flow pressure gradient relationship establishing module is configured to establish a relationship between gas well test gas production and flow pressure gradient based on test data of gas wells in the gas reservoir region that have conducted productivity test;

[0039] A gas well production layer middle formation pressure calculation module is configured to obtain the static pressure gradient of the gas well in the gas reservoir region based on the relationship between the gas well test gas production and the flow pressure gradient, and then determine the middle formation pressure of the production layer of the gas well to be developed;

[0040] A gas well production layer middle flow pressure calculation module is configured to obtain the flow pressure gradient of the well to be developed based on the test production of the well, and then calculate the middle flow pressure of the production layer of the well;

[0041] A productivity correction coefficient calculation module is configured to establish a binomial productivity equation based on the test data of the gas wells in the gas reservoir region that have conducted productivity test, and finally determine the productivity correction coefficient.

[0042] The system, device, model or unit described in the above scheme can be specifically implemented by a computer chip or entity, or by a product with certain functions. For the convenience of description, when describing the above device, various units are described respectively based on functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0043] Further, another aspect of the present application provides a computer device, comprising a processor, an input device, an output device and a memory, which are connected with each other; wherein the memory is configured to store a computer program, the computer program comprises program instructions, and the processor is configured to invoke the program instructions to execute the steps of the method for determining the calculation parameter of gas well productivity.

[0044] Further, another aspect of the present application provides a computer readable storage medium, characterized by: the computer readable storage medium stores a computer program, the computer program comprises program instructions, and the program instructions, when executed by a processor, cause the processor to execute the steps of the method for determining the calculation parameter of gas well productivity.

[0045] In the present application, the processor can be a central processing unit (CPU). The processor can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations thereof.

[0046] The memory, as a non-transitory computer readable storage medium, can be configured to store non-transitory software programs, non-transitory computer executable programs and units, such as the corresponding program units in the method of the present application. The processor executes various functions and application programs of the processor and work data processing by running the non-transitory software programs, instructions and modules stored in the memory, that is, implements the method for determining the calculation parameter of gas well productivity.

[0047] The memory can include a program storage area and a data storage area, wherein the program storage area can store an operating system and at least one application program required by a function; and the data storage area can store data created by the processor and the like. In addition, the memory can include a high-speed random access memory, and can also include a non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state memory device. In some embodiments, the memory can optionally include a memory remotely arranged with respect to the processor, and these remote memories can be connected to the processor through a network. Examples of the above network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0048] The one or more units are stored in the memory and, when executed by the processor, perform the method of determining the gas well productivity calculation parameter.

[0049] Those skilled in the art will understand that the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects.

[0050] Advantages of the present application:

[0051] 1. The present application uses a small number of test data for productivity test to establish a relationship between the test gas production and the flow pressure gradient, accurately calculates the formation pressure and the bottom hole flowing pressure parameters of the gas well to be developed for productivity calculation, and then uses the two test productivity equations obtained by the productivity test to solve the gas reservoir productivity correction coefficient. On this basis, the "one-point method" productivity formula is used to calculate the gas well productivity, and the accurate calculation of the gas well open flow capacity provides technical support for the reasonable production scale and the prediction of the cumulative gas production of the gas well. Therefore, the present application only needs to carry out a productivity test, and then the productivity calculation parameters of the remaining gas wells to be developed for productivity calculation in the gas reservoir region can be calculated, which significantly reduces the cost and period of the gas well productivity calculation.

[0052] 2. The present application is based on the analysis and calculation based on the measured data, and the error of the calculation result is small and the accuracy is high.

[0053] 3. The present application is not only suitable for determining the productivity calculation parameters of the gas well in the conventional gas reservoir such as carbonate rock and clastic rock, but also suitable for determining the productivity calculation parameters of the unconventional gas well such as shale gas and coalbed methane, and has wide application range and strong adaptability.

[0054] 4. The present application has no special requirements for the development well type of the gas well, and is suitable for straight wells, horizontal wells, inclined wells, highly deviated wells, and multi-lateral wells.

[0055] 5. The present application mainly uses the analytical method for solving, does not need to carry out iterative calculation, and does not need to use professional pipe flow software operation. The whole calculation process can be completed by using conventional office or graphic processing software such as Excel, Originlab, Sigmplot, and Matlab, and the operation is simple and efficient. BRIEF DESCRIPTION OF DRAWINGS

[0056] The foregoing and subsequent specific description of the present application will become more apparent when read in conjunction with the following drawings, in which:

[0057] Figure 1 is a flow chart of the method of the present application;

[0058] Figure 2 is a structural diagram of the device of the present application;

[0059] Figure 3 A relationship curve between gas production and flow pressure gradient is tested for the present application;

[0060] Figure 4 A binomial deliverability equation diagram is shown for the present application.

[0061] Figure 5 A relationship curve between gas production and flow pressure gradient is tested for the present application.

[0062] Figure 6 A binomial deliverability equation diagram is shown for the present application.

[0063] In the drawings:

[0064] 201, a gas well test gas production and flow pressure gradient relationship establishment module; 202, a gas well production layer middle formation pressure calculation module; 203, a gas well production layer middle flow pressure calculation module; 204, a deliverability correction coefficient calculation module. DETAILED DESCRIPTION

[0065] In order for those skilled in the art to better understand the technical solutions in the present application, the following will further illustrate the technical solutions for achieving the purposes of the present application through several specific embodiments. It should be noted that the technical solutions claimed by the present application include but are not limited to the following embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts should fall within the scope of protection of the present application.

[0066] Taking a carbonate gas reservoir in the central region of Sichuan Basin as an example, the method proposed in the present application is used to determine the deliverability calculation parameters of the gas wells in the gas reservoir to be developed for deliverability calculation. Among them, the ST1 well in the gas reservoir carried out a deliverability test, and the deliverability of three gas wells ST001-X1, ST001-X2, ST001-X4, which did not carry out deliverability test, needs to be calculated.

[0067] The ST1 well deliverability test is as follows: the deliverability test was carried out in April 2023, the production layer middle vertical depth of the well is 5204.7m, the pressure gauge was lowered to a vertical depth of 4929m during the test, and four system gas production tests were carried out during the test, and the test data are shown in Table 1. At the same time, using the shut-in pressure buildup test data obtained from the test gas well, the production layer middle formation pressure of the gas well is obtained through the test interpretation software as 47.382MPa.

[0068] Table 1 Summary of ST1 well deliverability test data

[0069]

[0070] Because the gas reservoir is a high and steep structure gas reservoir, the vertical depths of the middle production zones of the three gas wells ST001-X1, ST001-X2 and ST001-X4 are quite different, and the basic test conditions are shown in Table 2.

[0071] Table 2 Basic test conditions of three gas wells to be developed for productivity calculation

[0072]

[0073] (1) Establish the relationship between the test gas production and the flow pressure gradient of the gas well

[0074] The flow pressure data of the downhole pressure gauge, the wellhead oil pressure data and the vertical depth of the pressure gauge under four test systems of the ST1 well are substituted into the following formula (2) to calculate the flow pressure gradient corresponding to each test system (see Table 1);

[0075]

[0076] wherein p wfi represents the flow pressure corresponding to the i-th test system; p cfi represents the wellhead oil pressure corresponding to the i-th test system;

[0077] Then the test gas production and the flow pressure gradient data of each test system are plotted (see the attached figure), and based on the relationship curve between the test gas production and the flow pressure gradient, the linear regression is carried out to establish the relationship between the test gas production and the flow pressure gradient of the ST1 well, and the relationship is shown in the following formula (3); Figure 5

[0078] D = 0.00105q g + 0.243 (3);

[0079] wherein q g represents the test gas production of the ST1 well; D represents the flow pressure gradient; a and b are constants.

[0080] (2) Determine the formation pressure parameters of the middle production zone of the gas well to be developed for productivity calculation

[0081] According to the above formula (3), when the test gas production of the gas well is 0, the static pressure gradient D0 of the gas well in the entire gas reservoir region can be obtained, and D0 = 0.243 MPa / 100 m is calculated in this embodiment. The formation pressure of the middle production zone of the gas well which has carried out the productivity test is 47.382 MPa, and the formation pressure of the middle production zone of the gas well which has not carried out the productivity test is calculated by using formula (4), and the calculation results are shown in Table 3.

[0082]

[0083] ​Table 3 Formation pressure in the middle of the production layer of three gas wells to be developed for capacity calculation

[0084]

[0085] (3) Determine the flow pressure parameter in the middle of the production layer of the gas well to be developed for capacity calculation

[0086] Using the test gas production of the three gas wells to be developed for capacity calculation in Table 2, the flow pressure gradient of each gas well is calculated by substituting formula (3), and then the flow pressure gradient is substituted into the following formula (5) to calculate the flow pressure parameter in the middle of the production layer of each well. The calculation results are shown in Table 4.

[0087] p wfNC = 0.01H NC ·D NC + p cfNC (5);

[0088] Wherein, p wfNC represents the flow pressure in the middle of the production layer of the gas well to be developed for capacity calculation; D NC represents the flow pressure gradient of the gas well to be developed for capacity calculation; p cfNC represents the wellhead oil pressure of the gas well to be developed for capacity calculation;

[0089] Table 4 Test basic situation table of three gas wells to be developed for capacity calculation

[0090]

[0091] (4) Determine the value of the gas reservoir capacity correction coefficient α

[0092] Using the flow pressure gradient calculated by the four test systems of ST1 well, the flow pressure at each system pressure gauge is converted to the middle of the production layer, and the normalized pressure square difference corresponding to each system is calculated (Table 5 for calculation results); and a relationship diagram of test gas production and normalized pressure square difference is established (see Appendix Figure 6 ), regression is carried out through the relationship diagram, and thus the binomial capacity equation of ST1 well is established (see formula (6)). Then, the open flow capacity of ST1 well is calculated as 420.71×10 4 m 3 / d by using formula (6) to back-calculate.

[0093] Table 5 Calculation table of normalized pressure square difference of ST1 well

[0094]

[0095]

[0096] Finally, the capacity correction coefficient α value of the gas reservoir can be determined by using formula (7):

[0097]

[0098] In summary, the middle layer pressure, the middle layer flow pressure and the productivity correction coefficient obtained by using the above steps are used to calculate the open flow capacity of the three gas wells to be developed by the following formula (1), and the calculation results are shown in Table 6.

[0099]

[0100] Wherein, q g represents the test gas production of the gas well.

[0101] Table 6 Productivity calculation results of three gas wells to be developed

[0102]

[0103] The above is only a preferred embodiment of the present application, and does not hinder the present application in any form. Any simple modification or equivalent change made on the basis of the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for determining gas well productivity calculation parameters, characterized in that, The method includes the following steps: Step S1. Based on the test data of gas wells that have undergone production testing in the gas reservoir area, establish the relationship between the gas production and the flowing pressure gradient of the gas well test; Step S2. Based on the relationship between gas well test production and flowing pressure gradient, obtain the static pressure gradient of gas wells in the gas reservoir area, and then determine the formation pressure in the middle of the producing layer of the gas well to be used for production calculation. Step S3. Calculate the test production of the gas well based on the production capacity to be developed, obtain the flowing pressure gradient of the well, and then calculate the flowing pressure in the middle of the producing layer of the well; Step S4. Based on the gas well test data of the gas reservoir area where production capacity testing has been carried out, establish a binomial production capacity equation and finally determine the production capacity correction coefficient.

2. The method for determining gas well productivity calculation parameters according to claim 1, characterized in that, Step S1 includes: Based on the test data of gas wells that have been tested for production capacity in the gas reservoir area, the vertical depth of the downhole pressure gauge and the flowing pressure data and wellhead oil pressure data at the downhole pressure gauge corresponding to each test regime are obtained, and the flowing pressure gradient corresponding to each test regime is calculated. Based on the test gas production and flow pressure gradient corresponding to each test regime, a relationship between the test gas production and flow pressure gradient is established through regression.

3. The method for determining gas well productivity calculation parameters according to claim 1, characterized in that, Step S2 includes: The formation pressure in the middle of the producing layer of the gas well to be tested for production capacity is obtained based on the static pressure gradient, the formation pressure in the middle of the producing layer of the gas well that has already undergone production capacity testing in the gas reservoir area, the vertical depth in the middle of the producing layer, and the depth in the middle of the producing layer of the gas well to be tested for production capacity.

4. The method for determining gas well productivity calculation parameters according to claim 1, characterized in that, Step S3 includes: The test production of the gas well to be used for production capacity calculation is substituted into the relationship between the test gas production and the flowing pressure gradient of the gas well to obtain the flowing pressure gradient value of the well; then, based on the vertical depth of the middle of the producing layer and the oil pressure at the wellhead of the gas well to be used for production capacity calculation, the flowing pressure in the middle of the producing layer of the well is calculated.

5. The method for determining gas well productivity calculation parameters according to claim 1, characterized in that, Step S4 includes: Based on the formation pressure of the gas wells that have undergone production testing in the gas reservoir area, the bottom-hole flowing pressure and test production corresponding to each test regime, calculate the normalized pressure square difference corresponding to each test regime, draw a binomial production capacity equation diagram, obtain the values ​​of the binomial production capacity equation coefficients A and B through regression, and establish the corresponding binomial production capacity equation. The unobstructed flow rate of the gas wells that have undergone capacity testing is obtained based on the binomial capacity equation. Then, the capacity correction coefficient is calculated based on the coefficients A and B of the binomial capacity equation and the unobstructed flow rate of the gas wells that have undergone capacity testing.

6. The method for determining gas well productivity calculation parameters according to claim 2, characterized in that, In step S1, the calculation expressions for the flow pressure gradient corresponding to each test regime are as follows: Among them, D i p represents the flow pressure gradient corresponding to the i-th test regime; wfi p represents the mid-flow pressure of the gas well producing formation corresponding to the i-th test regime; cfi H represents the wellhead oil pressure corresponding to the i-th test regime; H is the vertical depth of the pressure gauge.

7. The method for determining gas well productivity calculation parameters according to claim 3, characterized in that, In step S2, the calculation expression for the formation pressure in the middle of the producing layer of the gas well to be calculated is as follows: Among them, P RC This indicates the formation pressure in the middle of the producing layer of a gas well that has undergone production testing; H C This indicates the vertical depth of the middle section of the producing formation in a gas well that has undergone production testing; H NC D0 represents the vertical depth of the middle of the producing formation of the gas well for which production calculations are to be performed; p represents the static pressure gradient. RNC This indicates the formation pressure in the middle of the producing layer of the gas well for which production calculations are to be carried out.

8. The method for determining gas well productivity calculation parameters according to claim 4, characterized in that, In step S3, the calculation expression for the mid-flow pressure of the producing formation of the gas well to be used for production capacity calculation is as follows: p wfNC =0.01H NC ·D NC +p cfNC (5); Where, p wfNC H represents the mid-flow pressure of the producing formation of the gas well for which production calculations are to be performed. NC D indicates the vertical depth of the middle of the producing layer of the gas well for which production calculations are to be carried out; NC This represents the flowing pressure gradient of the gas well for which production capacity calculations are to be performed; p cfNC This indicates the wellhead oil pressure of the gas well for which production capacity calculations are to be carried out.

9. An apparatus for determining calculation parameters of gas well productivity, characterized in that, The apparatus is used to implement the method according to any one of claims 1-8, and the apparatus comprises: The module for establishing the relationship between gas well test production and pressure gradient is used to establish the relationship between gas well test production and pressure gradient based on the test data of gas wells that have undergone production testing in the gas reservoir area. The gas well production zone mid-formation pressure calculation module obtains the static pressure gradient of gas wells in the gas reservoir area based on the relationship between gas well test production and flowing pressure gradient, and then determines the mid-formation pressure of the gas well to be calculated for production capacity. The gas well production zone mid-flow pressure calculation module obtains the flow pressure gradient of the well based on the test production of the gas well to be developed, and then calculates the flow pressure in the middle of the production zone of the well. The production capacity correction coefficient calculation module establishes a binomial production capacity equation based on the test data of gas wells that have undergone production capacity testing in the gas reservoir area, and finally determines the production capacity correction coefficient.

10. A computer device, characterized in that: The device includes a processor, an input device, an output device, and a memory, which are interconnected. The memory is used to store a computer program, which includes program instructions. The processor is configured to invoke the program instructions to execute the method described in any one of claims 1-8.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, the computer program including program instructions that, when executed by a processor, cause the processor to perform the method described in any one of claims 1-8.

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