A method for classifying shale gas well types based on improved Duong method production decline analysis

Abstract

This invention relates to the field of shale gas exploration and development technology, and in particular to a method for classifying shale gas wells based on an improved Duong method for production decline analysis. This invention proposes a method for classifying shale gas wells based on an improved Duong method for production decline analysis. It fully considers the unique reservoir production mechanisms (different ratios of free gas and adsorbed gas), more complex seepage channels (micro-nano pores, etc.), and stronger reservoir heterogeneity of deep shale gas. Furthermore, production decline is influenced by numerous factors such as geology, engineering, and development. This invention establishes a shale gas well classification method based on an improved Duong method for production decline analysis, overcoming the limitations of existing methods that only address shallow and medium-depth shale gas and fail to consider the unique geological, engineering, and development characteristics of deep shale gas exploration and development. This method is more accurate, efficient, and better applicable to the efficient classification and management of deep shale gas wells.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of shale gas exploration and development, and particularly relates to a shale gas well type classification method based on improved Duong method production decline analysis. BACKGROUND

[0002] Traditional factors affecting shale gas well production decline include development and geology. At present, the production decline law and well type classification method of deep shale gas with a depth of 3500 meters or more are not clear. This is mainly because, compared with shallow shale gas, the reservoir space (molecular pores, micro-nano pores, etc.), production mechanism (matrix surface adsorption, gas desorption, diffusion, free gas, etc.), and reservoir percolation channel (fracture network formed by fracturing, natural fractures, micro-nano or molecular pores) of deep shale gas are more complex, and the reservoir heterogeneity is stronger, resulting in that the existing shale gas production decline analysis and well type classification method are not applicable to deep shale gas.

[0003] The commonly used shale gas production decline analysis methods in China at present include the exponential decline and hyperbolic decline empirical formula proposed by Arps (1945), the extended exponential decline, and the Duong decline model method. The Arps decline method continuously solves and analyzes the change law of the decline exponent D and b. However, in general, the quality of production data is greatly affected by factors such as shale gas well fracturing fluid flowback, water production, adjustment of oil nozzle size, coiled tubing well passage, and repeated fracturing, resulting in great uncertainty of the analysis result of the Arps decline method. Wang Chuanjie et al. (2014) considered that the traditional Arps production decline analysis method must be modified before being applied to shale gas wells. In addition, the improved Duong decline, power exponential decline, and improved power exponential decline are suitable for boundary-dominated flow and linear flow. Wang Ke et al. (2019) proposed that the Duong method can be used to accurately estimate the ultimate reserves (EUR) only when the gas well enters the boundary flow, and data fluctuation has a great impact on the Duong method.

[0004] Moreover, the above methods are only applicable to shallow shale gas, and do not consider the unique geological engineering and development characteristics of deep shale gas exploration and development, and cannot well study and classify deep shale gas with a depth of 3500 meters or more. Therefore, there is a need for a shale gas well type classification method that overcomes the above problems. SUMMARY

[0005] The present application aims at overcoming the above-mentioned deficiencies in the prior art, and provides a shale gas well type classification method based on improved Duong method production decline analysis.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0007] A shale gas well type classification method based on improved Duong method production decline analysis, comprising the following steps:

[0008] S1: obtaining actual production data of a shale gas well to be classified; the actual production data includes actual daily production time, actual daily gas production and actual cumulative gas production;

[0009] S2: obtaining gas well analysis parameters, and obtaining initial daily gas production according to the gas well analysis parameters, and corresponding abandonment date at a preset abandonment pressure;

[0010] S3: obtaining the gas well analysis parameters of the shale gas well to be classified at the abandonment date;

[0011] S4: obtaining predicted daily gas production and predicted cumulative gas production of the improved Duong method production decline analysis before the abandonment date according to the gas well analysis parameters at the abandonment date, and generating a shale gas well production decline curve;

[0012] S5: dividing the shale gas well production decline curve into three decline stages, and classifying the shale gas well to be classified according to the proportion of the duration of each decline stage to the whole life cycle time of the gas well;

[0013] Among them, the three decline stages include early decline stage, middle decline stage and late decline stage; the first classification includes early decline stage dominant type, middle decline stage dominant type and late decline stage dominant type;

[0014] S6: classifying the shale gas well to be classified according to the relationship between the actual daily gas production and the predicted daily gas production in the shale gas well production decline curve; the second classification includes normal production well, pressure relief production well and pathological well.

[0015] As a preferred scheme of the present application, the gas well analysis parameters include the straight line intercept A and the straight line slope-m of the rectangular coordinate curve, and the time function t a and a of the traditional Duong method cumulative production; and the gas well analysis parameters satisfy the following formula:

[0016] Ln(q / G P )=A-m×Ln(t),

[0017]

[0018] a=e A ,

[0019] Among them, Ln() is the natural logarithm symbol with constant e as the base, q is the actual daily gas production, G p is the actual cumulative gas production, and t is the actual daily production time.

[0020] As a preferred embodiment of the present invention, the method for obtaining the initial daily gas production in step S2 is as follows:

[0021] Based on the actual cumulative gas production G p Let t be the ordinate. a Plot G as the x-axis. p With t a The slope of the straight line passing through the origin is the initial daily gas production q1.

[0022] As a preferred embodiment of the present invention, the calculation formulas for the predicted daily gas production and the predicted cumulative gas production in step S4 are as follows:

[0023]

[0024] G P，改进Duong法 =q1×t a ,

[0025] Where, q 改进Duong For the predicted daily gas production, G P，改进Duong法 The predicted cumulative gas production is [value].

[0026] As a preferred embodiment of the present invention, the shale gas well production decline curve is expressed in terms of t a q is the x-coordinate 改进Duong The vertical axis is denoted by .

[0027] As a preferred embodiment of the present invention, the abandonment date in S2 is obtained based on IHS Harmony software and mathematical analytical model of multi-stage fracturing shale gas horizontal wells.

[0028] As a preferred embodiment of the present invention, the mathematical analytical model based on multi-stage fracturing shale gas horizontal well includes the following assumptions: the reservoir is horizontal and homogeneous, the reservoir thickness is equal, the internal temperature of the reservoir is constant, there is no fluid flow at the end of the horizontal well, and the flow in the reservoir is single-phase.

[0029] As a preferred embodiment of the present invention, S6 further includes plotting the actual daily gas production on the shale gas well production decline curve.

[0030] As a preferred embodiment of the present invention, the criteria for the second category classification are as follows:

[0031] When the actual daily gas production equals the predicted daily gas production, it is classified as a normal production well;

[0032] When the actual daily gas production is greater than the predicted daily gas production, it is classified as a pressure relief production well;

[0033] When the actual daily gas production is less than the predicted daily gas production, the well is classified as a sick well.

[0034] An electronic device includes at least one processor and a memory communicatively connected to the at least one processor; the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method described above.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention proposes a shale gas well classification method based on an improved Duong method for production decline analysis. Due to the adsorption characteristics (free gas content around 85%) and strong stress sensitivity of deep shale gas reservoirs (stress sensitivity can reduce the stable production period by one year and cumulative gas production by 20%), the production decline characteristics and classification methods for deep shale gas differ from other developed shale gas types. Addressing the practical needs of advanced prediction of deep gas well production decline and dynamic evaluation of the effects of post-production well allocation and drainage / gas production measures, this invention establishes two deep shale gas well classification methods. These methods provide technical support for shale gas regional comparison, well production system formulation, precise well classification management, dynamic change analysis of well production parameters, and gas field capacity construction planning. This method overcomes the limitations of existing methods, which only address shallow and medium-depth shale gas and fail to consider the unique geological, engineering, and development characteristics of deep shale gas exploration and development. It is more accurate, efficient, and better applicable to the efficient classification and management of deep shale gas wells. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating a method for classifying shale gas well types based on an improved Duong method production decline analysis, as described in Embodiment 1 of the present invention.

[0038] Figure 2 This is a schematic diagram illustrating the acquisition of parameters A and m in a shale gas well type classification method based on an improved Duong method production decline analysis, as described in Embodiment 5 of the present invention.

[0039] Figure 3 This is a schematic diagram illustrating the acquisition of parameters A and m in a shale gas well type classification method based on improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0040] Figure 4 This is a schematic diagram illustrating the acquisition of parameters A and m in a shale gas well type classification method based on an improved Duong method production decline analysis, as described in Embodiment 5 of the present invention.

[0041] Figure 5This is a schematic diagram illustrating the initial daily gas production of well A1 in a shale gas well type classification method based on improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0042] Figure 6 This is a schematic diagram illustrating the initial daily gas production of well A2 in a shale gas well type classification method based on an improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0043] Figure 7 This is a schematic diagram illustrating the initial daily gas production of well A3 in a shale gas well type classification method based on an improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0044] Figure 8 In the shale gas well type classification method based on the improved Duong method production decline analysis described in Embodiment 5 of the present invention, well A1 is obtained in P... 废弃 The corresponding obsolescence date T 废弃 A schematic diagram;

[0045] Figure 9 In the shale gas well type classification method based on the improved Duong method production decline analysis described in Embodiment 5 of the present invention, well A2 is obtained in P... 废弃 The corresponding obsolescence date T 废弃 A schematic diagram;

[0046] Figure 10 In the shale gas well type classification method based on the improved Duong method production decline analysis described in Embodiment 5 of the present invention, well A3 was obtained in P... 废弃 The corresponding obsolescence date T 废弃 A schematic diagram;

[0047] Figure 11 The shale gas well type classification method based on the improved Duong method production decline analysis described in Embodiment 5 of the present invention is based on the abandoned date T. 废弃 Gas well analysis parameters A, m, a, t a A schematic diagram;

[0048] Figure 12 This is a schematic diagram of the shale gas well production decline curve of well A1 in a shale gas well type classification method based on improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0049] Figure 13 This is a schematic diagram of the shale gas well production decline curve of well A2 in the shale gas well type classification method based on the improved Duong method production decline analysis described in Embodiment 5 of the present invention.

[0050] Figure 14This is a schematic diagram of the shale gas well production decline curve of well A3 in a shale gas well type classification method based on improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0051] Figure 15 This is a schematic diagram showing the proportion of the three stages of wells A1, A2, and A3 in the total life cycle of a shale gas well in a shale gas well type classification method based on improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0052] Figure 16 This is a schematic diagram of the shale gas well production decline curves of wells A1, A2, and A3 in a shale gas well type classification method based on improved Duong method production decline analysis as described in Embodiment 5 of the present invention.

[0053] Figure 17 This is a schematic diagram of an electronic device according to Embodiment 6 of the present invention, which utilizes a shale gas well type classification method based on the improved Duong method production decline analysis described in Embodiment 1. Detailed Implementation

[0054] 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.

[0055] Example 1

[0056] like Figure 1 As shown, a method for classifying shale gas well types based on improved Duong method production decline analysis includes the following steps:

[0057] S1: Obtain the actual production data of the shale gas wells to be classified; the actual production data includes the actual daily production time, the actual daily gas production, and the actual cumulative gas production.

[0058] S2: Obtain gas well analysis parameters, and based on the gas well analysis parameters, obtain the initial daily gas production and the corresponding abandonment date at the preset abandonment pressure;

[0059] S3: Obtain the well analysis parameters of the shale gas well to be classified at the date of abandonment;

[0060] S4: Based on the gas well analysis parameters at the abandoned date, obtain the predicted daily gas production and predicted cumulative gas production of the improved Duong method production decline analysis before the abandoned date, and generate the shale gas well production decline curve.

[0061] S5: Divide the shale gas well production decline curve into three decline stages, and classify the shale gas wells to be classified into the first category according to the different proportions of the duration of each decline stage to the total life cycle of the gas well;

[0062] The three decreasing stages include the initial decreasing stage, the middle decreasing stage, and the final decreasing stage; specifically:

[0063] Initial stage of decline: In the initial stage of gas well production, after the predicted daily gas production has reached its maximum value, the horizontal axis adopts dimensionless time ta (dimensionless three-digit number), which is the first optimal fitting stage of the predicted daily gas production curve.

[0064] Mid-decline phase: Starting from the dimensionless time ta (dimensionless three-digit number) at the end of the initial decline phase, this is the second optimal fitting phase of the predicted daily gas production curve.

[0065] The final stage of decline: Starting from the dimensionless time ta (dimensionless three-digit number) at the end of the middle stage of decline, it is the third best-fit stage of the predicted daily gas production curve.

[0066] The first classification includes early-stage decline-dominant, mid-stage decline-dominant, and late-stage decline-dominant types. Based on this first classification standard, the following guiding strategies can be used to operate modified gas wells:

[0067] The type of gas well dominated by the initial decline phase indicates that the stress sensitivity of this type of gas well is relatively the strongest. The stable production period and cumulative gas production are also most affected by the production allocation in the initial decline phase. In the initial decline phase of this type of gas well, pressure maintenance and production control should be adopted to maximize the stable production period and cumulative gas production. It is important to avoid excessive daily gas production in the initial decline phase, as strong stress sensitivity can cause premature closure of the fracturing fractures, which in turn leads to a significant reduction in the stable production period and cumulative gas production.

[0068] Mid-term decline dominant type: This indicates that the stress sensitivity of this type of gas well is relatively strong. In the early stage of decline, phased production control and pressure maintenance should be adopted for this type of gas well; in the mid-term decline, strict pressure maintenance and production control should be implemented to maximize the stable production period and cumulative gas production.

[0069] The type of gas well dominated by the late decline stage indicates that the stress sensitivity of this type of gas well is relatively weak. In the early stage of the decline, pressure release production (i.e., without controlling the gas flow rate) can be adopted. In the middle stage of the decline, phased production control and pressure maintenance should be adopted. Finally, in the late stage of the decline, strict pressure maintenance and production control should be implemented to maximize the stable production period and cumulative gas production.

[0070] S6: Based on the relationship between the actual daily gas production and the predicted daily gas production in the shale gas well production decline curve, the shale gas wells to be classified are further divided into a second category; the second category includes normal production wells, depressurized production wells, and diseased wells. Normal production wells: Gas wells whose actual daily gas production equals the declining predicted daily gas production, and which have not experienced abnormal operating conditions such as casing deformation, fracturing loss, or adjacent well leakage.

[0071] Depressurization production wells: Gas wells that do not use measures such as nozzles or throttle valves to restrict the flow of natural gas.

[0072] Sick wells: Gas wells whose actual daily gas production is less than the predicted daily gas production. The auxiliary gas production measures (such as drainage gas production) usually adopted for this type of gas well are not ideal, or abnormal conditions such as tubing breakage, casing deformation, fracturing loss, and cross-flow to adjacent wells occur.

[0073] The criteria for the second category are as follows:

[0074] When the actual daily gas production equals the predicted daily gas production, it is classified as a normal production well;

[0075] When the actual daily gas production is greater than the predicted daily gas production, it is classified as a pressure relief production well;

[0076] When the actual daily gas production is less than the predicted daily gas production, the well is classified as a sick well.

[0077] After classification according to the second category standard, it is indicated that the following guidance strategies can be used to operate modified gas wells:

[0078] Once a well is identified as being in normal production, it is understood that no human intervention is necessary at this stage. This avoids the negative impacts of blindly intervening in the normal production of this type of well (such as blindly increasing the well's output, causing premature closure of artificially fractured cracks, and reducing the well's cumulative gas production).

[0079] For wells identified as being in a "pathological" state, auxiliary gas production measures (such as foam drainage and gas lift) are typically ineffective or result in abnormal conditions like tubing rupture. This provides technical support for developing targeted production stabilization measures for these wells. For example, it allows for optimizing the injection ratio of foam drainage agents for wells using foam drainage, ultimately achieving the desired results, increasing production, and eventually removing them from the "pathological" category to become normal production wells.

[0080] The identified depressurized production wells provide technical support for developing targeted phased pressure control production strategies for gas wells, thereby increasing the final recoverable reserves of the gas wells and ultimately converting these wells into normal production wells.

[0081] With the gradual increase in domestic deep shale gas production, the practical significance of conducting comprehensive classification of deep shale gas wells is becoming increasingly important. This method addresses the practical needs of predicting the decline in deep gas well production in advance and dynamically evaluating the effectiveness of post-production measures such as rational well allocation and drainage for gas production. It establishes two classification methods for deep shale gas wells, avoiding the need to determine the stress sensitivity type and drainage effectiveness of each well through experiments on reservoir conditions. This provides technical support for shale gas regional comparison, well production system formulation, precise well classification management, analysis of dynamic changes in well production parameters, and the preparation of gas field capacity construction plans.

[0082] In general, the decline in production of deep shale gas wells can be divided into three stages: early, middle, and late decline. The adsorption characteristics of deep shale gas reservoirs (free gas accounts for approximately 85%, as confirmed by molecular simulation experiments; free gas dominates with increasing burial depth, and adsorption capacity decreases with higher temperatures, reaching near-equilibrium at pressure 15 MPa) and their strong stress sensitivity (stress sensitivity can reduce the stable production period by one year and cumulative gas production by 20%, with varying degrees of stress sensitivity affecting wells with different fracture development characteristics) determine that the decline in production and the classification methods for deep shale gas differ from those for other types of shale gas. This method fills the gap in well classification methods based on production decline prediction for deep shale gas, providing technical support for the formulation and precise classification of production systems for different types of deep shale gas wells.

[0083] Example 2

[0084] This embodiment is a specific implementation of the method described in Embodiment 1, including the following steps:

[0085] S1: Obtain the actual production data of the shale gas wells to be classified; the actual production data includes the actual daily production time t (unit: h) and the actual daily gas production q (unit: 10). 4 m 3 / d) and actual cumulative gas production G p (Unit: 10) 4 m 3 / d).

[0086] S2: Obtain gas well analysis parameters, and based on these parameters, determine the initial daily gas production and the corresponding abandonment date at the preset abandonment pressure. The gas well analysis parameters include the linear intercept A and slope -m of the rectangular coordinate curve, and the time function t for the cumulative production using the traditional Duong method. a and a.

[0087] S21: Obtain parameters A and m. Based on the actual production data, calculate Ln(q / G). P)=Am×Ln(t), where A is the intercept of the line on the rectangular coordinate curve; -m is the slope of the line.

[0088] S22: Obtain parameters a and t a According to a = e A , t a This is the time function for accumulating output using the traditional Duong method.

[0089] S23: Obtain the accurate initial daily gas production q1 (unit: 10) 4 m 3 / d). Based on the actual cumulative gas production G p (Unit: 10) 4 m 3 / d) is the ordinate, t a Plot G as the x-axis. p With t a The slope of the straight line passing through the origin is the most accurate q1.

[0090] S24: Obtain the gas well's abandoned pressure P predicted by analytical method. 废弃 (Unit: MPa) Corresponding obsolescence date T 废弃 .

[0091] S3: Obtain the shale gas well to be divided at the date of abandonment T. 废弃 Gas well analysis parameters A, m, a, t a .

[0092] S4: Based on the gas well analysis parameters at the abandoned date, obtain the predicted daily gas production and predicted cumulative gas production of the improved Duong method production decline analysis before the abandoned date, and generate the shale gas well production decline curve.

[0093] S41: Get the value at the expiration date T 废弃 Predicting daily gas production q using the improved Duong method's declining production analysis 改进Duong , (Unit: 10) 4 m 3 / d).

[0094] S42: Get the value at the expiration date T 废弃 Predicting cumulative gas production G using the improved Duong method's declining production analysis P，改进Duong法 G P，改进Duong法 =q1×t a (Unit: 10) 4 m 3 / d).

[0095] S43: with t a q is the x-coordinate改进Duong Plot the shale gas well production decline curve with y as the vertical axis.

[0096] S5: Divide the shale gas well production decline curve into three decline stages, and classify the shale gas wells to be classified into the first category according to the different proportions of the duration of each decline stage to the total life cycle of the gas well.

[0097] S51: Based on the three-stage characteristics of production decline in deep shale gas wells (i.e., initial decline, middle decline, and final decline), identify the optimal production decline curves for each well across these three stages. Each decline stage is represented by t... a q is the x-coordinate 改进Duong Plot the shale gas well production decline curve with y as the vertical axis.

[0098] S52: Based on the different proportions of the duration of each of the three stages of production decline in deep shale gas wells to the total life cycle of the gas well (including: early stage of decline-dominant, mid-stage of decline-dominant, and late stage of decline-dominant), the first category of shale gas wells to be classified is completed.

[0099] S6: The shale gas wells to be classified are classified into a second category based on the relationship between the actual daily gas production and the predicted daily gas production in the shale gas well production decline curve; the second category includes normal production wells, depressurized production wells, and diseased wells.

[0100] The criteria for the second category are as follows:

[0101] When the actual daily gas production q = the predicted daily gas production q 改进Duong At that time, it was classified as a normal production well;

[0102] When the actual daily gas production q > the predicted daily gas production q 改进Duong At that time, it was classified as a pressure relief production well;

[0103] When the actual daily gas production q < the predicted daily gas production q 改进Duong At that time, it was classified as a pathological well.

[0104] Example 3

[0105] The difference between this embodiment and embodiment 2 is that step S6 further includes plotting the actual daily gas production on the shale gas well production decline curve to facilitate comparison when performing the second classification.

[0106] Example 4

[0107] The difference between this embodiment and the previous embodiment is that the abandonment date in S2 is obtained based on IHS Harmony software and mathematical analytical model analysis based on multi-stage fracturing shale gas horizontal wells.

[0108] The mathematical analytical model for multi-stage fracturing shale gas horizontal wells references a linear composite model (theoretically detailed in Ozkan et al. 2009, SPE 125043 and SPE 121290). This model primarily considers two types of reservoirs: the internal reservoir of the SRV (stimulated reservoir) and the unstimulated external reservoir. The horizontal well penetrates the internal SRV reservoir. The model includes the following assumptions: the reservoir is horizontal and homogeneous, the reservoir thickness is uniform, the internal reservoir temperature is constant, there is no fluid flow at the end of the horizontal well, and the flow within the reservoir is single-phase.

[0109] Example 5

[0110] This embodiment is a specific application of the method described in Embodiment 4, specifically for classifying shale gas wells A1, A2, and A3 into different types, including the following steps:

[0111] S1: As shown in Table 1, obtain the actual production data of shale gas wells A1, A2, and A3 to be classified.

[0112] Table 1. Actual production data of shale gas wells A1-A3 collected by the gas reservoir management PCS system.

[0113]

[0114] S2: Obtain gas well analysis parameters, and based on the gas well analysis parameters, obtain the initial daily gas production and the corresponding abandonment date at the preset abandonment pressure.

[0115] S21: Obtain parameters A and m. For example... Figures 2-4 As shown, based on the actual production data, parameters for classifying shale gas wells A1, A2, and A3 are determined. Figures 2-4 It can be seen that the parameters of well A1 are A = 1.8114, m = 1.4054; the parameters of well A2 are A = 1.0482, m = 1.2539; and the parameters of well A3 are A = 2.2996, m = 1.5154.

[0116] S22: Obtain parameters a and t a As shown in Table 2.

[0117] Table 2 shows the parameters 'a' and 't' obtained from wells A1, A2, and A3 in the shale gas well classification method. a

[0118]

[0119]

[0120] S23: Obtain the accurate initial daily gas production q1 (unit: 10) 4 m 3 / d). The initial daily gas production q1 of the shale gas wells A1, A2, and A3 to be divided are as follows: Figures 5-7 As shown.

[0121] S24: As Figures 8-10 As shown, the analytical method is used to predict the gas well's abandonment pressure P. 废弃 (Unit: MPa) Corresponding obsolescence date T 废弃 .

[0122] S3: As shown in Table 3 and Figure 11 As shown, the shale gas well to be divided was obtained on the abandonment date T. 废弃 Gas well analysis parameters A, m, a, t a .

[0123] Table 3 shows the parameter t obtained from wells A1, A2, and A3 using the analytical method and HIS Harmony software. a

[0124]

[0125] S4: Based on the gas well analysis parameters at the abandoned date, obtain the predicted daily gas production and predicted cumulative gas production from the improved Duong method production decline analysis before the abandoned date, and generate the shale gas well production decline curve.

[0126] S41: Get the value at the expiration date T 废弃 Predicting daily gas production q using the improved Duong method's declining production analysis 改进Duong , (Unit: 10) 4 m 3 / d).

[0127] S42: Get the value at the expiration date T 废弃 Predicting cumulative gas production G using the improved Duong method's declining production analysis P，改进Duong法 G P，改进Duong法 =q1×t a (Unit: 10) 4 m 3 / d).

[0128] S43: with t a q is the x-coordinate 改进Duong Using the vertical axis as the ordinate, plot the shale gas well production decline curves. The production decline curves for shale gas wells A1, A2, and A3 to be classified are shown below. Figures 12-14 As shown.

[0129] S5: Divide the shale gas well production decline curve into three decline stages, and classify the shale gas wells to be classified into the first category according to the different proportions of the duration of each decline stage to the total life cycle of the gas well.

[0130] S51: Based on the three-stage characteristics of production decline in deep shale gas wells (i.e., initial decline, middle decline, and final decline), identify the optimal production decline curves for each well across these three stages. Each decline stage is represented by t... a q is the x-coordinate 改进Duong Plot the shale gas well production decline curve with y as the vertical axis.

[0131] S52: Based on the different proportions of the duration of each of the three stages of production decline in deep shale gas wells to the total lifespan of the well (including: early decline-dominant, mid-decline-dominant, and late decline-dominant), the first category of the shale gas wells to be classified is completed. For example... Figure 15 As shown, wells A1 and A3 are identified as gas wells in the early stage of decline, while well A2 is identified as a gas well in the middle stage of decline.

[0132] S6: Based on the relationship between the actual daily gas production and the predicted daily gas production in the shale gas well production decline curve, the shale gas wells to be classified are further divided into a second category; the second category includes normal production wells, depressurized production wells, and diseased wells. Figures 12-14 as well as Figure 16 It can be seen that A1: q = q 改进Duong A2: q>q 改进Duong A3: q 改进Duong This indicates that Well A3 is a pathological well. Furthermore, actual production practice shows that Well A3 was recently subjected to cross-flow from a neighboring well, confirming that it is indeed a pathological well, demonstrating the practical value of this method in field applications.

[0133] Example 6

[0134] like Figure 17 As shown, an electronic device includes at least one processor, a memory communicatively connected to the at least one processor, and at least one input / output interface communicatively connected to the at least one processor. The memory stores instructions executable by the at least one processor, which, when executed, enable the at least one processor to perform a shale gas well type classification method based on improved Duong method production decline analysis as described in the foregoing embodiments. The input / output interface may include a display, keyboard, mouse, and USB interface for inputting and outputting data.

[0135] ​Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0136] When the integrated units of this invention are implemented as software functional units and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this invention, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0137] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A shale gas well type classification method based on improved Duong method production decline analysis, characterized in that, The method comprises the following steps: S1: obtaining actual production data of a shale gas well to be classified; The actual production data comprises actual daily production time, actual daily gas production and actual cumulative gas production; S2: calculating gas well analysis parameters according to the actual production data obtained in S1, obtaining initial daily gas production according to the gas well analysis parameters, and obtaining an abandonment date corresponding to a preset abandonment pressure; S3: obtaining gas well analysis parameters of the shale gas well to be classified at the abandonment date; S4: obtaining predicted daily gas production and predicted cumulative gas production of the improved Duong method production decline analysis before the abandonment date according to the gas well analysis parameters at the abandonment date, and generating a shale gas well production decline curve; S5: dividing the shale gas well production decline curve into three decline stages, and classifying the shale gas well to be classified according to different proportions of the duration of each decline stage in the whole life cycle time of the gas well; The three decline stages comprise an initial decline stage, a middle decline stage and a final decline stage; and the first classification comprises an initial decline stage dominant type, a middle decline stage dominant type and a final decline stage dominant type; S6: classifying the shale gas well to be classified according to the relationship between the actual daily gas production and the predicted daily gas production in the shale gas well production decline curve; and the second classification comprises a normal production well, a pressure relief production well and a sick well.

2. The method according to claim 1, wherein, The gas well analysis parameters include a straight line intercept of a rectangular coordinate curve A and a straight line slope m , and a time function of cumulative production of a conventional Duong method and a ; and the gas well analysis parameters satisfy the following formula: ， ， ， wherein, Ln () is the natural logarithm symbol with base e, is the actual daily gas production, is the actual cumulative gas production, is the actual daily production time.

3. The method according to claim 2, wherein, The method for obtaining the initial daily gas production in S2 is as follows: with the actual cumulative gas production as the ordinate, with the elapsed time as the abscissa, a straight line is drawn through the origin, and the slope of this line is the initial daily gas production .

4. The method according to claim 3, wherein, The calculation formulae of the predicted daily gas production and the predicted cumulative gas production in S4 are as follows: ， ， wherein, is the predicted daily gas production, is the predicted cumulative gas production.

5. The method according to claim 4, wherein, The shale gas well production decline curve, with as the horizontal coordinate, as the vertical coordinate.

6. The method of claim 1, wherein the method is characterized by, The abandonment date in S2 is obtained based on IHS Harmony software and a mathematical analysis model of multi-stage fractured shale gas horizontal wells.

7. The method according to claim 6, wherein, The mathematical analysis model of multi-stage fractured shale gas horizontal wells comprises the following assumptions: the reservoir is horizontal and homogeneous, the reservoir thickness is equal, the internal temperature of the reservoir is constant, there is no fluid flow at the end of the horizontal well, and the reservoir is single-phase flow.

8. The method according to claim 1, wherein, S6 further comprises plotting the actual daily gas production on the shale gas well production decline curve.

9. The method according to claim 8, wherein, The criteria for the second classification are as follows: When the actual daily gas production = the predicted daily gas production, the well is classified as a normal production well; When the actual daily gas production > the predicted daily gas production, the well is classified as a pressure relief production well; When the actual daily gas production < the predicted daily gas production, the well is classified as a sick well.

10. An electronic device, comprising: The device comprises at least one processor and a memory connected to the at least one processor in communication; the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to execute the method in any one of claims 1 to 9.

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