An integrated gas well deliverability evaluation method

Abstract

The present application relates to a kind of integrated gas well productivity evaluation method, comprising the following steps: S1, obtaining gas well relevant data: formation pressure, gas well standard production gas and bottom hole flowing pressure data;S2, solving laminar flow term coefficient A, turbulence term coefficient B, solve gas well open flow capacity;A, B coefficient is solved using plotting method, corresponding linear formula is obtained using linear regression fitting, the intercept and slope of formula are A, B value;A, B and P e Substitute binomial formula (2), open flow capacity q AOF Is solved: S3, if binomial productivity equation coefficient A, B exists negative value, using pressure term correction value correction to obtain positive value coefficient A' and B';Then, based on A' and B' are substituted into formula (2) to obtain open flow capacity q AOF The gas well productivity evaluation method of the present application makes full use of the data obtained during the development of gas well for analysis and evaluation, and realizes efficient and accurate evaluation combined with the characteristics of gas well, which is of great significance for production guidance.

Description

Technical Field

[0001] This invention relates to a method for evaluating the productivity of gas wells, belonging to the field of oil and gas field development technology. Background Technology

[0002] In the development of gas fields, gas well productivity and dynamic prediction are crucial throughout the entire production process. Their accuracy directly impacts the overall development effectiveness and benefits of the gas field, forming the foundation for its scientific development. Gas well productivity is a parameter reflecting the current production capacity of a gas well, primarily influenced by reservoir geological conditions, drilling and completion techniques, and reservoir stimulation. How to accurately conduct gas well productivity assessments has always been a hot research topic both domestically and internationally.

[0003] In the book "Natural Gas Engineering", the gas well productivity formula under the quasi-steady state is a binomial productivity equation (Li Shilun et al. Natural Gas Engineering [M]. Beijing: Petroleum Industry Press, 2008). This productivity equation is widely used in various gas fields. Based on the binomial productivity equation of gas wells, Zhang Kai et al. combined the iterative calculation method of non-Darcy coefficients to derive a gas well productivity evaluation method applicable to the early stage of development of strongly heterogeneous carbonate gas reservoirs (Zhang Kai, Yang Shan, Zhao Xiang, Yan Yuhan, Peng Xiaojuan. Gas well productivity evaluation method in the early stage of development of strongly heterogeneous carbonate gas reservoirs. Science and Industry, 2021, 21(1): 231-234.).

[0004] Based on the binomial production capacity equation, Chen Chunyan et al. derived a binomial production capacity equation of degree n based on the actual gas reservoir, which effectively solved the difficulty in evaluating the production capacity of gas wells in the high-pressure gas reservoir of Longwangmiao Formation in Moxi (Chen Chunyan, Ruan Jifu, Wu Lihua, Liu Liujun, Yang Hui, Zhong Liping. Production capacity equation and solution method of gas wells in high-pressure gas reservoir of Longwangmiao Formation in Moxi Block. Oil and Gas Well Testing, 2021, 30(2): 67-73.).

[0005] Ma Shuai et al. considered the formation pressure drop within the effective supply range during the test process based on the traditional binomial method, and obtained a new binomial productivity equation by regression. They successfully solved the abnormal situation of the conventional binomial productivity equation for high-pressure and low-permeability wells, and provided a solution for the correction of abnormal productivity of high-pressure and low-permeability gas wells (Ma Shuai, Zhang Fengbo, Wang Wenjuan, Cha Yuqiang, Wang Yanli. Improvement and solution of binomial productivity equation for high-pressure and low-permeability gas wells. Journal of Southwest Petroleum University: Natural Science Edition, 2020, 42(4): 121-126).

[0006] After analyzing PVT data, simulated wells and field example wells of typical gas reservoirs in my country, Sun Hedong et al. clarified the applicable conditions of the simplified method of the binomial pressure method for gas well productivity evaluation (Sun Hedong, Meng Guangren, Cao Wen, Su Xiaobin, Liang Zhidong, Zhang Runjie, Zhu Songbai, Wang Shengjun. Applicable conditions of binomial pressure method and pressure leveling method for gas well productivity evaluation. Natural Gas Industry, 2020, 40(1): 69-75).

[0007] In summary, the binomial method remains the mainstream method in current capacity evaluation research.

[0008] The most common method for increasing production capacity is conventional backpressure testing (also known as multi-point testing). This method involves shutting in the well to determine the maximum wellhead (or bottomhole) pressure when there is no fluid accumulation at the bottom. After the well is opened, tests are conducted sequentially according to the designed operating procedure. At each test flow rate, production continues until the wellhead pressure stabilizes, and then the standard state gas production rate q is precisely measured. sc and bottom hole flowing pressure P wf (Li Shilun et al. Natural Gas Engineering [M]. Beijing: Petroleum Industry Press, 2008).

[0009] In recent years, as the exploration of new gas reservoirs has progressed from the initial shallow and medium-depth terrestrial layers to the deep terrestrial layers and then to the marine layers, the reservoirs, fluids, drilling and completion processes, and stimulation technologies have also become different. As a result, more and more "abnormal" situations have been encountered during multi-point well testing in actual production testing.

[0010] There are two main problems:

[0011] 1) The gas reservoirs in the new area are generally low-permeability to tight gas reservoirs. During the testing period, the flow rate reached a stable state in a short time under each testing regime. The data collected made it impossible to directly calculate the production capacity using the production capacity formula.

[0012] 2) Implementing integrated engineering and geology: With the improvement of the transformation technology, some new wells adopt large-scale volumetric fracturing. Insufficient backflow during the testing period leads to increased near-well pollution and increased gas well skin coefficient, resulting in significant errors in production capacity evaluation during the testing period. Summary of the Invention

[0013] The purpose of this invention is to address the anomalies existing in the application of existing technologies in new gas reservoirs, and to overcome the limitations and large errors of the traditional binomial evaluation method, thereby providing a gas well productivity evaluation method.

[0014] To achieve the aforementioned objectives, the following technical solutions are provided:

[0015] An integrated gas well productivity evaluation method includes the following steps:

[0016] S1. Obtain gas well-related data: Formation pressure P e Standard gas production q of gas well sc and bottom hole flowing pressure P wf data;

[0017] S2. Solve for the laminar flow coefficient A and the turbulent flow coefficient B to calculate the gas well's free-flow rate q. AOF ;

[0018] Based on the binomial production capacity equation (1), the coefficients A and B are determined using a graphical method, with q sc x-axis Plot the vertical axis and use linear regression to fit the corresponding linear formula, where the intercept and slope are values ​​A and B, respectively.

[0019]

[0020] P e p represents formation pressure, in MPa; wf q represents the bottom hole flowing pressure, in MPa; sc Indicates standard gas production volume, m 3 / d; A represents the laminar flow term coefficient; B represents the turbulent flow term coefficient.

[0021] Place A, B, and P e Substituting into the binomial formula (2), the unobstructed flow rate q is obtained. AOF :

[0022]

[0023] S3. If the coefficients A and B of the binomial capacity equation have negative values, the positive coefficients A' and B' are obtained by correcting with the pressure term correction value; then, based on A' and B', the unobstructed flow rate q is calculated by substituting them into the binomial formula (2). AOF ;

[0024] The method for obtaining positive coefficients A' and B' by correcting the pressure term is as follows: add a correction coefficient C to the pressure term to obtain equation (3);

[0025]

[0026] With q sc x-axis Plotting the ordinate, a linear regression fit is used to obtain the corresponding linear formula. The intercept and slope in the formula are the corresponding A' and B' of the binomial formula, respectively. Then, the unobstructed flow rate q is calculated according to the binomial formula (2). AOF .

[0027] S4. If the gas well has undergone large-scale modification or incomplete backflow during testing leads to inaccurate gas well productivity evaluation, then correct the skin coefficient S in the laminar flow term A to obtain a new laminar flow term A'; then calculate the unobstructed flow rate q. AOF ;

[0028]

[0029] Specifically, this includes the following two methods: obtaining the gas well skin coefficient based on pressure recovery well testing or obtaining the gas well skin coefficient based on dynamic fitting, and a new laminar flow term coefficient A'.

[0030] S401. The skin coefficient of the gas well is obtained based on the pressure recovery test:

[0031] Perform pressure recovery tests to obtain the bottom hole pressure at the shut-in time and the pressure recovery data when the shut-in time is Δt; calculate the skin coefficient S.

[0032] If the skin coefficient S is positive, substitute the skin coefficient S value into the value of the laminar flow term coefficient A obtained by the binomial capacity equation (1); then, calculate the new coefficient A' corresponding to S = 0 (decontamination), and obtain the new coefficients A' and B in the binomial capacity formula;

[0033]

[0034]

[0035]

[0036] In the formula, Viscosity is T; temperature is T. is the deviation coefficient; K is the permeability; h is the effective thickness of the gas layer; r w r is the radius of the well bottom; e γ is the seepage radius; S is the skin coefficient; β is the turbulence coefficient, a coefficient introduced in the derivation; g This represents the relative density of natural gas.

[0037] Based on the updated A' and B, the unobstructed flow rate q is calculated using the binomial formula (2). AOF ;

[0038] S402. The skin coefficient of the gas well is obtained based on dynamic fitting:

[0039] Using the Blasingame plot method, a typical production decline curve plot was established by introducing pseudo-pressure normalized production and pseudo-material balance time. After fitting the normalized production expression formula, the production integral expression, the production integral derivative expression, and the formula corresponding to the actual production data of the gas reservoir, the corresponding skin coefficient S can be obtained.

[0040] If the skin coefficient S is positive, substitute the value of skin coefficient S into the value of laminar flow coefficient A obtained by the binomial capacity equation (1); then, calculate the new coefficient A' corresponding to S = 0 (decontamination), and obtain the new coefficients A' and B in the binomial capacity formula; solve q based on the updated A' and B. AOF .

[0041] This invention makes full use of the data obtained during the gas well development process, combines the effects of influencing factors during the gas well construction process, and conducts analysis and evaluation in sequence. It achieves high-efficiency and accurate evaluation by combining the characteristics of gas wells, and can complete the evaluation of gas well production capacity at the lowest production cost, which is of great significance for production guidance.

[0042] Furthermore, the integrated gas well production capacity evaluation method also includes step S5: calculating q according to the one-point method production capacity formula (23). AOF :

[0043]

[0044] In the formula,

[0045] Based on A(A'), B(B'), and q obtained in steps S2-S4 AOF Substituting into equation (22), we obtain the coefficient α of the one-point method production capacity formula (23):

[0046]

[0047] Then, the coefficient α is substituted into the one-point production capacity formula (23) to calculate the production capacity of the wells that have undergone one-point production capacity testing in each gas reservoir. This can be used to solve the problem again for gas wells whose production capacity has been calculated, to verify the accuracy of the one-point production capacity formula (23), or to quickly solve the problem for gas wells whose production capacity has not yet been calculated.

[0048] The above A(A'), B(B'), q AOF Including A, B, q AOF Or A', B, q AOF Or A', B', q AOF Several scenarios.

[0049] In actual gas reservoir development, to reduce development costs and improve efficiency, only a portion of gas wells typically undergo production testing. This makes single-point production evaluation increasingly important. Based on the unobstructed flow rate q obtained from the completed production tests... AOF Calculate the coefficient α of the one-point method production capacity formula for other gas wells in the gas reservoir to realize one-point method production capacity assessment, improve production efficiency, and reduce costs and increase efficiency.

[0050] Furthermore, step S3 specifically includes:

[0051] 301. Adding a correction factor C to the pressure term yields equation (3):

[0052]

[0053] 302, with q sc x-axis Plot the graph on the ordinate and use the linear regression formula to obtain the corresponding linear equation; calculate the coefficient of determination R of the linear equation. 2 When A' and B' are positive and R 2 When large enough (usually R) 2If the coefficient of determination is greater than 0.9, the goodness of fit is considered to meet the requirements, and step 303 is performed. Otherwise, the correction coefficient C is adjusted, linear regression is performed again, and the coefficient of determination R is calculated. 2 Preferably, R 2 Large enough means that when A' and B' are positive, then R 2 Greater than 0.9; R may also be 2 If A' and B' become negative after exceeding a certain value, then A' and B' should be ensured to be positive first, and then R should be taken. 2 Maximum value.

[0054] 303. The intercept and slope in the formula are the corresponding A' and B' values ​​of the binomial formula corrected by the pressure term correction value; then, based on A' and B', the unobstructed flow rate q is calculated by substituting them into formula (2). AOF .

[0055] Further, step S401 is,

[0056] Assume the gas well production time is t. p If the shut-in time is Δt, then the pressure-recovery unsteady flow equation has three forms: pressure, pressure square, and pseudo-pressure. The pressure form equation is:

[0057] Pressure type:

[0058]

[0059] In the formula, P i P represents the original formation pressure. ws The bottom hole pressure is the pressure when the well is shut in for a time of Δt. This represents the average pressure.

[0060] Pressure recovery value:

[0061]

[0062] △P ws =P ws -P wf (t p )

[0063] In the formula, P ws P is the bottom hole pressure when the shut-in time is Δt; wf (t p () represents the bottom hole pressure at the time of well shut-in.

[0064] From equation (4), it can be seen that the pressure recovery data P ws —— The relationship is linear, with the slope m of the line being...

[0065]

[0066] The bottom hole pressure recovery value at Δt = 1h is

[0067]

[0068] According to the above formula, we can obtain:

[0069] Formation flow coefficient:

[0070]

[0071] Penetration rate:

[0072]

[0073] Epidermal coefficient:

[0074]

[0075] If the epidermal coefficient S is positive, substituting S into the following formula will give the values ​​of coefficients A and B.

[0076]

[0077]

[0078] Then, by setting the skin coefficient S = 0, we can obtain the new coefficient A', thus obtaining the new coefficients A' and B in the binomial productivity formula;

[0079] Based on the updated A' and B, the unobstructed flow rate q is calculated using equation (1). AOF .

[0080] In the formula, γ g Indicates the relative density of natural gas; Where K is the formation flow coefficient, K is the permeability, and T is the temperature. r is the gas deviation coefficient; w r is the bottom radius of the well (replaced by the drill bit radius). wa The apparent contamination radius fitted to blasingame; r e γ is the seepage radius; β is the turbulence coefficient, a coefficient introduced in the derivation; g S is the relative density of natural gas; S is the skin coefficient. The compression factor is 1.

[0081] If the skin coefficient S is positive, it indicates that the gas well is contaminated, and the binomial production capacity formula is inaccurate. Considering that the contamination can be gradually resolved after the gas well is put into production and the true production capacity of the gas well is released, the skin coefficient S = 0 is set to obtain a new coefficient A', which is the accurate coefficient and can accurately assess the true production capacity of the gas well.

[0082] Furthermore, in step S402,

[0083] Using the Blasingame plot method, a typical yield decline curve plot was established by introducing pseudo-pressure normalized yield and pseudo-material balance time; after fitting, the corresponding permeability K and skin coefficient S can be obtained.

[0084] Normalized output expression

[0085]

[0086] Production integral expression

[0087]

[0088] Production integral derivative expression

[0089]

[0090] Substitute equations (11) to (13) into the graph to establish a typical output decline curve.

[0091] Furthermore, in step S402, the Blasingame diagram method is used.

[0092] The formula corresponding to the actual production data of the gas reservoir is:

[0093] Normalized output expression

[0094]

[0095] Production integral expression

[0096]

[0097] Production integral derivative expression

[0098]

[0099] After fitting, the corresponding permeability K, epidermal coefficient S, etc. can be obtained.

[0100]

[0101] The skin coefficient S of the gas well was obtained by fitting and solving the matching problem using the Blasingame plot method.

[0102] Penetration rate k is

[0103]

[0104] r wa for

[0105]

[0106] The epidermal coefficient S is...

[0107]

[0108] If the epidermal coefficient S is positive, substitute the epidermal coefficient S into the production capacity formula (1) to obtain the values ​​of coefficients A and B, and then set S = 0 to obtain the new coefficient A'; solve q based on the updated A' and B. AOF If the epidermal coefficient S is negative or zero, calculate q according to the values ​​of coefficients A and B. AOF .

[0109] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0110] This invention employs a combination of macroscopic and microscopic methods, as well as testing and production approaches. It addresses situations where conventional binomial formulas are inapplicable or where evaluations contain errors by classifying and correcting them according to different causes. Appropriate correction methods are then applied to update coefficients and evaluate the effects, thereby establishing a new method suitable for evaluating the production capacity of gas wells in new areas. This provides technical support for accurately evaluating gas well production capacity and scientifically developing gas fields.

[0111] (1) In response to the serious bottom pollution caused by large-scale volumetric fracturing, which leads to large errors in gas well productivity evaluation, a method was established to determine the binomial productivity equation by combining the skin coefficient with the dynamics of productivity testing.

[0112] (2) Based on the binomial production capacity equation, a set of gas well production capacity evaluation processes for different working conditions was systematically established. Attached Figure Description

[0113] Figure 1 This is a flowchart illustrating the main technical process of the present invention.

[0114] Figure 2 The figures show the binomial curve before and after C-value correction.

[0115] Figure 3 This is a standard binomial curve during the testing period.

[0116] Figure 4 The production curve of a gas well shows that a certain well underwent large-scale volumetric fracturing. During the trial production period, the well's pressure and production showed a "double increase" trend and then maintained stable production.

[0117] Figure 5 The gas well test production data were fitted into the Blasingame model.

[0118] Figure 6 To obtain the α-plot (linear regression) for a gas reservoir using the one-point method.

[0119] Figure 7 It is a curve showing the relationship between gas well production capacity and storage capacity.

[0120] Figure 8 It is a curve showing the relationship between gas well productivity and storage / permeability. Detailed Implementation

[0121] The integrated gas well productivity evaluation method of this invention has the following main process: Figure 1 As shown, it mainly includes the following aspects:

[0122] (1) Data selection

[0123] (2) Calculate the values ​​of coefficients A and B in the binomial formula.

[0124] Select pressure and production data from at least three systems that are relatively stable during multi-point testing and can reflect the true situation of gas wells.

[0125] Binomial formula for production calculation principle: The conventional binomial production capacity formula is equation (1), which is obtained by calculating the formation pressure P. e In this case, q is obtained through testing sc and p wf Data, calculate the coefficients A and B in the formula; combine the values ​​of A and B with p e Substituting the values ​​into Equation 2 will yield the gas well production capacity (according to Equation (2), A and B in the binomial formula should both be positive values).

[0126]

[0127]

[0128]

[0129]

[0130] In the formula p e p wf q sc A and B represent formation pressure (MPa), bottom hole flowing pressure (MPa), and gas production (m³), respectively. 3 / d; laminar flow term coefficient; turbulent flow term coefficient.

[0131] 1) Determining the coefficients of A and B using the graphical method

[0132] According to the formula, with q sc x-axis Plot the vertical axis and use linear regression to obtain the corresponding linear formula, where the intercept and slope are the values ​​of A and B, respectively, as in equation (1).

[0133] 2) Cases where A and B have negative values: Positive coefficients are obtained through pressure correction.

[0134] Principle: By correcting the C value of the pressure term, the binomial curve is transformed into a straight line with normal (A and B are positive) and a sufficiently high linear fit.

[0135] ① Add a correction factor C to the pressure term (Equation 3).

[0136]

[0137] ② with q sc x-axis Plotting the ordinate, a linear regression formula is used to obtain the corresponding linear equation; if the linear regression equation R... 2 If the value is sufficiently large (generally greater than 0.9), then the intercept and slope in the formula are the corresponding A and B values ​​for the binomial formula, respectively; otherwise, the correction coefficient C is replaced, and the calculation is repeated. Preferably, the linear regression fitting formula R... 2 Greater than 0.95.

[0138] like Figure 2 The figure shows the binomial curve before and after C-value correction. From... Figure 2 As can be seen from graph a, the initial values ​​of A (52.396) and B (-0.2577) obtained through multiple regression do not meet the condition that both A and B are positive. Therefore, C-value correction is performed, and a C-value of 780 is chosen, which results in a high goodness of fit (R²). 2 =0.9519), the values ​​of A and B are 18.018 and 0.111 respectively, both positive values. Calculate q. AOF The unobstructed flow rate is 1.2706 million cubic meters per day.

[0139] 3) Inaccurate gas well productivity evaluation due to incomplete backflow during testing and large-scale volumetric fracturing: Correct the skin coefficient S in the laminar flow coefficient A value.

[0140] ① Obtain the skin coefficient of the gas well through pressure recovery testing

[0141] Based on the principle of pressure field superposition, assuming the gas well production time is tp and the subsequent shut-in time is Δt, the pressure-recovery unsteady flow equation has three forms: pressure, pressure square, and pseudo-pressure. The pressure form equation is as follows:

[0142] Pressure type:

[0143]

[0144] Pressure recovery value:

[0145]

[0146] △P ws =P ws -P wf (t p )

[0147] In the formula P ws P wf (t p ) are the bottom hole pressure when the shut-in time is Δt and the bottom hole pressure at the shut-in time, respectively.

[0148] From equation (4), it can be seen that the pressure recovery data P ws —— The relationship is expressed as a linear one, with the slope of the line being...

[0149]

[0150] The bottom hole pressure recovery value at Δt = 1h is

[0151]

[0152] The formation flow coefficient, permeability, and skin coefficient can be obtained from the above formula:

[0153]

[0154]

[0155]

[0156] ② The skin coefficient of the gas well is obtained by dynamic fitting.

[0157] Using the Blasingame plot method, a typical yield decline curve plot was established by introducing pseudo-pressure normalized yield and pseudo-material balance time. The corresponding formula is:

[0158] Normalized output expression

[0159]

[0160] Production integral expression

[0161]

[0162] Production integral derivative expression

[0163]

[0164] The formula corresponding to the actual production data of the gas reservoir is:

[0165] Normalized output expression

[0166]

[0167] Production integral expression

[0168]

[0169] Production integral derivative expression

[0170]

[0171] After fitting, the corresponding permeability, epidermal coefficient, and other values ​​can be obtained.

[0172]

[0173] The penetration rate k is

[0174]

[0175] r wa That is

[0176]

[0177] S is...

[0178]

[0179] Substituting the skin coefficient into the production capacity formula (1), we can find the values ​​of coefficients A and B. Then, ignoring the influence of the skin coefficient, we can find the new coefficient A', and obtain the new coefficients A' and B in the binomial production capacity formula, formula (21).

[0180]

[0181]

[0182]

[0183] like Figures 3 to 5 As shown. Figure 3 This is the initial binomial curve during the testing of a certain well. The graph shows that the values ​​of A and B for this well are 85.171 and 4.6975, respectively. Based on the initial binomial productivity formula, the well's q is calculated. AOF It is 231,500 cubic meters per day.

[0184] Figure 4 This reflects the trial production situation after the well test. The test employed large-scale volumetric fracturing stimulation, with an injection volume of 7248.41 m³. 3 During this period, the flowback rate was 52.78%, and no pressure recovery test was conducted. After the trial production, the well's pressure and production showed a "double increase" trend and then maintained stable production.

[0185] Therefore, the well test data was fitted into the Blasingame model. Figure 5 From Equation 20, we obtain S = 4.85 for the well. Substituting this value into the A value in Equation 1, we obtain A' (S = 0) as 47.64. Therefore, we obtain the actual q after the pollution is removed. AOFIt is 648,100 cubic meters per day.

[0186] (3) Using the binomial formula to calculate the product

[0187] Substituting the positive values ​​of A (A') and B into Formula 2, we can obtain the corresponding unobstructed flow rate q. AOF .

[0188] (4) Derivation of the production capacity formula for the one-point method

[0189] In actual gas reservoir development, in order to reduce development costs and further improve efficiency, multi-point well testing is usually carried out on only a portion of the gas wells. This makes single-point production capacity evaluation increasingly important, and the principle is as follows:

[0190] After simplifying the binomial production capacity equation in equation (1), we get:

[0191] P D =α(q) g / q AOF )+(1-α)(q g / q AOF ) 2

[0192] In the formula,

[0193]

[0194] Solving equation (22) yields the following results.

[0195]

[0196] This formula allows for a more accurate determination of production from wells undergoing point-based production testing in various gas reservoirs.

[0197] like Figure 6 As shown, q has been obtained through the above steps. AOF , with A+Bq AOF Plotting A as the x-axis and A as the y-axis, and using linear regression to fit the corresponding linear formula, we obtain the α-plot of the gas reservoir using the one-point method (linear regression).

[0198]

[0199] According to equation (22), the α value of the new gas reservoir is obtained by linear regression as 0.51. Figure 6 Substituting this value into equation (23), we obtain the one-point method production capacity formula suitable for the gas reservoir in this area. Equation (24) can be used to evaluate the production capacity of one-point method test wells in this area.

[0200] The present invention will be further described in detail below with reference to experimental examples and specific embodiments. However, this should not be construed as limiting the scope of the above-mentioned subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0201] <Example 1>

[0202] In the past two years, 19 new wells have been drilled in the Western Sichuan New Area, of which 14 have undergone multi-point testing, but only 2 can be evaluated using conventional productivity formulas. The above methods can be used to effectively evaluate the productivity of all 14 wells.

[0203] Table 1. Testing Well Status in Western Sichuan New Area

[0204]

[0205] 1) The production effect after negative correction of coefficients A and B of the binomial curve

[0206] Correlation analyses were conducted using both single-factor and multi-factor methods. The analyses showed that the production capacity pattern of the Leikoupo Formation gas reservoir in western Sichuan is consistent with the geological understanding of the reservoir in its early stages (mainly a porous reservoir, with a positive correlation between reservoir properties and production capacity). Therefore, the overall production capacity assessment of the gas reservoir is considered accurate. Figure 7 , Figure 8 ). Figure 7 It is a curve showing the relationship between gas well production capacity and storage capacity. Figure 8 It is a curve showing the relationship between gas well productivity and storage / permeability.

[0207] 2) The use of large-scale volumetric fracturing and incomplete flowback during testing led to errors in the gas well productivity assessment. Correction was performed on one deep well to determine the productivity after decontamination. The corrected productivity matched the well's trial production and subsequent production, indicating that the corrected productivity assessment was more accurate.

[0208] <Example 2>

[0209] Similar to Example 1, the gas field in the Western Sichuan New Area was analyzed using a one-point method formula to determine production. The results are as follows:

[0210] The alpha values ​​of each gas reservoir in the new area were obtained (Table 2).

[0211] Table 2. One-point method α table for gas reservoirs in the new area

[0212]

[0213] Based on the α value of the one-point method for gas reservoirs in the new area, a new one-point method production calculation formula is formed:

[0214]

[0215] In the formula,

[0216] Calculate the unobstructed flow rate q of the gas well using the production formula of the one-point method in the new area. AOF The compliance rate of capacity evaluation reached over 85% (Table 3).

[0217] Table 3. Evaluation Table of the Effect of the One-Point Method (Unit: 10,000 cubic meters / day)

[0218] hashtag Binary capacity New Area One-Point Production Capacity error Accuracy (%) CG561 12.9 12.92 0.19 99.81 CH100 40.37 31.64 -21.63 78.37 X202 40.173 38.26 -4.76 95.24 X5 15.04 12.6 -16.24 83.76 X2 127.17 129.22 1.61 98.39 X856 101.91 109.53 7.48 92.52 X851 151.4 146.57 -3.19 96.81 PZ6-2D 157.2 153.52 -2.34 97.66 YS1 82 68.18 -16.85 83.15 PZ4-4D 150.83 115.24 -23.59 76.41 PZ5-4D 113.01 85.28 -24.54 75.46 PZ3-4D 320.32 320.45 0.04 99.96 PZ8-5D 109.86 92.76 -15.56 84.44 PZ4-5D 127.06 100.53 -20.88 79.12 average 110.66 101.19 -10.02 88.65

Claims

1. An integrated gas well productivity evaluation method, comprising the following steps: S1. Obtain gas well-related data: Formation pressure P e Gas well production q under standard conditions sc and bottom hole flowing pressure P wf data; S2. Solve for the laminar flow coefficient A and the turbulent flow coefficient B to calculate the gas well's free-flow rate q. AOF ; Based on the binomial production capacity equation (1), the coefficients A and B are determined using a graphical method, with q sc x-axis Plot the vertical axis and use linear regression to fit the corresponding linear formula, where the intercept and slope are values ​​A and B, respectively. （1） P e Represents formation pressure, in MPa; Indicates bottom hole flowing pressure, MPa; This indicates the standard gas production rate, in m³. 3 / d; A represents the laminar flow term coefficient; B represents the turbulent flow term coefficient; Place A, B, and P e Substituting into the binomial formula (2), the unobstructed flow rate q is obtained. AOF : （2） S3. If the coefficients A and B of the binomial capacity equation have negative values, the positive coefficients A' and B' are obtained by correcting with the pressure term correction value; then, based on A' and B', the unobstructed flow rate q is calculated by substituting them into the binomial formula (2). AOF ; The method for obtaining positive coefficients A' and B' by correcting the pressure term is as follows: add a correction coefficient C to the pressure term to obtain equation (3). （3） With q sc x-axis Plotting the ordinate, a linear regression fit is used to obtain the corresponding linear formula. The intercept and slope in the formula are the corresponding A' and B' of the binomial formula, respectively. Then, the unobstructed flow rate q is calculated according to the binomial formula (2). AOF ; S4. If the gas well has undergone large-scale modification or the backflow during testing is incomplete, leading to inaccurate evaluation of the gas well's production capacity, then the skin coefficient S in the laminar flow term A should be corrected to obtain a new laminar flow term A', and then the unobstructed flow rate q should be calculated. AOF ; Specifically, this includes the following two methods: obtaining the gas well skin coefficient based on pressure recovery well testing or obtaining the gas well skin coefficient based on dynamic fitting, and then solving for the new laminar flow term coefficient A'; S401. The skin coefficient of the gas well is obtained based on the pressure recovery test: Perform pressure recovery tests to obtain the bottom hole pressure at the shut-in time and the pressure recovery data when the shut-in time is Δt; calculate the skin coefficient S. S402. The skin coefficient of the gas well is obtained based on dynamic fitting: Using the Blasingame plot method, a typical production decline curve plot was established by introducing pseudo-pressure normalized production and pseudo-material balance time. The corresponding skin coefficient S was obtained by fitting the formula corresponding to the actual production data of the gas reservoir using the normalized production expression formula, the production integral expression, and the production integral derivative expression. If the skin coefficient S is positive, substitute the value of the skin coefficient S into the value of the laminar flow coefficient A obtained by the binomial capacity equation (1); then, calculate the new coefficient A' corresponding to S=0, and obtain the new coefficients A' and B in the formula of the binomial capacity equation (1); In the formula, Viscosity is T; temperature is T. is the deviation coefficient; K is the permeability; h is the effective thickness of the gas layer; r w r is the radius of the well bottom; e γ is the seepage radius; S is the skin coefficient; β is the turbulence coefficient; γ g The relative density of natural gas; Based on the updated A' and B, the unobstructed flow rate q is calculated using the binomial formula (2). AOF .

2. The integrated gas well productivity evaluation method according to claim 1, characterized in that, It also includes step S5: If only some gas wells are tested at multiple points, then the unobstructed flow rate q is calculated according to the one-point method production capacity formula (23). AOF : （23） In the formula, Based on A or A', B or B', q obtained in steps S2-S4 AOF Substituting into equation (22), we obtain the coefficient α of the one-point method production capacity formula (23): （22） Then, the coefficient α is substituted into the one-point production capacity formula (23), and the production capacity of the wells for one-point production capacity testing of each gas reservoir is calculated.

3. The integrated gas well productivity evaluation method according to claim 1, characterized in that, Step S3 is as follows: S301. Add a correction factor C to the pressure term to obtain equation (3): （3） S302, with q sc x-axis Plot the graph on the ordinate and use the linear regression formula to obtain the corresponding linear equation; calculate the coefficient of determination R of the linear equation. 2 When A' and B' are positive and R 2 If the coefficient of determination is greater than 0.9, the goodness of fit is considered to meet the requirements, and step S303 is performed. Otherwise, the correction coefficient C is adjusted, linear regression is performed again, and the coefficient of determination R is calculated. 2 ; S303, the intercept and slope in the formula are the corresponding A' and B' values ​​of the binomial formula corrected by the pressure term correction value; then, based on A' and B', the unobstructed flow rate q is calculated by substituting them into formula (2). AOF .

4. The integrated gas well productivity evaluation method according to claim 1, characterized in that, Step S401 is, Assume the gas well production time is t. p If the shut-in time is Δt, then the pressure-recovery unsteady flow equation has three forms: pressure, pressure square, and pseudo-pressure. The pressure form equation is: Pressure type: （4） In the formula, P i P represents the original formation pressure. ws The bottom hole pressure is the pressure when the well is shut in for a time of Δt. Average pressure; Pressure recovery value: （5） In the formula, The bottom hole pressure is the pressure when the well is shut in for a time of Δt. This represents the bottom hole pressure at the moment of well shut-in. As can be seen from equation (4), the pressure recovery data The relationship is linear, with the slope m being... （6） The bottom hole pressure recovery value at Δt=1h is （7） According to the above formula, we can obtain: Formation flow coefficient: （8） Penetration rate: （9） Epidermal coefficient: （10） If the epidermal coefficient S is positive, substituting S into the following formula will give the values ​​of coefficients A and B. Then, by setting the skin coefficient S=0, we can obtain the new coefficient A', thus obtaining the new coefficients A' and B in the binomial production capacity formula; Based on the updated A' and B, the unobstructed flow rate q is calculated using equation (1). AOF ; In the formula, γ g Indicates the relative density of natural gas; Where K is the formation flow coefficient, K is the permeability, and T is the temperature. r is the gas deviation coefficient; w The bottom radius is represented by the drill bit radius instead; r e γ is the seepage radius; β is the turbulence coefficient; g S is the relative density of natural gas; S is the skin coefficient. The compression factor is 1.

5. The integrated gas well productivity evaluation method according to claim 1, characterized in that, In step S402, The Blasingame plot method was used to establish a typical yield decline curve plot by introducing pseudo-pressure normalized yield and pseudo-material balance time; after fitting, the corresponding permeability K and skin coefficient S were obtained. Normalized output expression （11） Where, r wa The apparent contamination radius fitted to blasingame; Production integral expression （12） Production integral derivative expression （13） Substitute equations (11) to (13) into the graph to establish a typical output decline curve.

6. The integrated gas well productivity evaluation method according to claim 5, characterized in that, In step S402, the Blasingame diagram method is used. The formula corresponding to the actual production data of the gas reservoir is: Normalized output expression （14） Production integral expression （15） Production integral derivative expression （16） After fitting, the corresponding permeability K and epidermal coefficient S are obtained. （17） The skin coefficient S, r of the gas well was obtained by fitting and solving the matching problem using the Blasingame plot method. wa The apparent pollution radius fitted to blasingame.

7. The integrated gas well productivity evaluation method according to claim 6, characterized in that, Penetration rate k is （18） r wa for （19） The epidermal coefficient S is... （20） If the skin coefficient S is positive, substitute the skin coefficient S into the binomial capacity equation (1) to obtain the values ​​of coefficients A and B, and then set S=0 to obtain the new coefficient A'; based on the updated A' and B, solve for the unobstructed flow rate q. AOF If the skin coefficient S is negative or zero, calculate the unobstructed flow rate q according to the values ​​of coefficients A and B. AOF .

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