Method and device for evaluating flowback effect of shale gas well

Abstract

The invention discloses a shale gas well flowback effect evaluation method and device which are applied to a shale gas well, and the method comprises the steps that firstly, the equivalent ground total flow is calculated according to the wellhead instantaneous gas production rate, the wellhead instantaneous water production rate, the volume coefficient of dimensionless gas and the volume coefficient of dimensionless water; then, according to the equivalent ground total flow, the original stratum pseudo-pressure and the gas well bottom hole flow pseudo-pressure, the yield regularized pressure is calculated, and a relation curve of the yield regularized pressure, the size of the gas well throttling valve in the flowback stage and time is drawn; and under the condition that the relation curve shows that the gas well productivity is enhanced and the reservoir is improved, an equivalent ground total flow and time double logarithmic curve is drawn, comprehensive parameters of the shale gas well are obtained according to the equivalent ground total flow and time double logarithmic curve, and finally the corresponding relation between the comprehensive parameters of the shale gas well and the final recoverable reserves is established. The shale gas well type is determined through the corresponding relation, the reservoir improvement degree after shale gas well fracturing transformation can be reflected, and the gas well flowback stage effect can be evaluated.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas field development, and in particular to a method and device for evaluating the flowback effect of a shale gas well. Background Art

[0002] Shale gas reservoirs are unconventional resources. In order to develop shale gas at scale, a combination of "long well section horizontal wells + volume fracturing technology" must be adopted. At present, shale gas in southern Sichuan mainly relies on the "10,000 cubic meters of liquid + 1,000 cubic meters of sand" volume fracturing construction scale, with more than 1,000 wells in production. After the fracturing of shale gas wells, they usually go through two stages: flowback and production. Under the same geological conditions, affected by the fracturing process, the degree of fracturing transformation of gas wells is different, showing different flowback and production characteristics. At present, shale gas wells in southern Sichuan carry out post-fracturing flowback by gradually enlarging the oil nozzle, which can not only remove the liquid and non-supporting proppant in the wellbore, but also clear the channel for gas seepage. At the same time, the flowback stage is also an important stage for evaluating the post-fracturing effect of the gas well and maintaining the formation energy to the greatest extent.

[0003] Due to the complex laws of the shale gas well backflow stage, and the fact that most domestic and foreign oil companies pursue short-term returns and high test production, they often ignore the characteristics of the backflow stage and focus on the production stage to obtain high EUR (Estimated Ultimate Recovery). No relevant research has been carried out on the use of the characteristics of the shale gas well backflow stage to achieve effect evaluation. With the increase in domestic shale gas reserves and production, the existing shale gas well production effect evaluation technology is only applicable to the gas well production stage after the backflow is completed, and has not yet achieved the evaluation of the gas well effect in the backflow stage. The data samples of shale gas well backflow stage are becoming increasingly huge. How to obtain key information from the huge data body is an important way to evaluate the shale gas well effect in the backflow stage of shale gas wells and guide the maintenance of gas well production capacity in the later stage. Therefore, the existing problems of difficult data analysis, insufficient effect evaluation methods, and lack of timeliness of effect evaluation in the backflow stage of shale gas horizontal wells need to be solved urgently. Summary of the invention

[0004] The purpose of this application is to provide a method and device for evaluating the flowback effect of a shale gas well in order to overcome the existing technical defects. The type of shale gas well is determined by corresponding relationships, which can reflect the degree of reservoir improvement after shale gas well fracturing and evaluate the effect of the gas well flowback stage.

[0005] The purpose of this application is achieved through the following technical solutions:

[0006] In the first aspect, the present application proposes a method for evaluating the flowback effect of a shale gas well, which is applied to a shale gas well and comprises:

[0007] The equivalent total surface flow is calculated based on the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas, and the volume coefficient of the dimensionless water;

[0008] Calculate the production regularization pressure according to the equivalent total surface flow, the original formation pseudo pressure and the gas well bottom flow pseudo pressure, and draw a relationship curve between the production regularization pressure, the gas well throttle valve size and time during the flowback stage;

[0009] When the relationship curve indicates that the gas well productivity is enhanced and the reservoir is improved, a double logarithmic curve of equivalent surface total flow and time is drawn, and comprehensive parameters of the shale gas well are obtained according to the double logarithmic curve of equivalent surface total flow and time;

[0010] A corresponding relationship between the comprehensive parameters of the shale gas well and the final recoverable reserves is established, and the type of the shale gas well is determined based on the corresponding relationship.

[0011] In a possible implementation, the step of obtaining the comprehensive parameters of the shale gas well according to the double logarithmic curve of the equivalent total surface flow rate and time includes:

[0012] Determining the linear flow stage of the shale gas well according to the double logarithmic curve of equivalent total surface flow and time;

[0013] Obtaining a slope value of the linear flow stage;

[0014] The slope value is used in combination with PVT related parameters to calculate the comprehensive parameters of the shale gas well.

[0015] In a possible implementation, the PVT-related parameters include formation temperature, formation porosity, gas viscosity, and gas comprehensive compressibility coefficient, and the shale gas well comprehensive parameters include: The calculation formula is: Where T represents the formation temperature, φ represents the formation porosity, m represents the slope value, μ represents the gas viscosity, c t Indicates the comprehensive compressibility factor of gas.

[0016] In a possible implementation, the equivalent total surface flow q tol The calculation formula is: tol =(q g *B g +q w *B w ) / B g , where q g is the instantaneous gas production at the wellhead of the shale gas well, q w is the instantaneous water production at the wellhead of the shale gas well, B g is the volume coefficient of the dimensionless gas, B w is the dimensionless volume coefficient of water.

[0017] In a possible implementation, the calculation formula for the production regularization pressure is: Where RNP is the yield normalization pressure, m(p i ) is the original formation pseudo pressure, m(p wf ) is the pseudo bottom flow pressure of the gas well.

[0018] In a possible implementation manner, the double logarithmic curve of equivalent total surface flow and time further includes a skin influence stage and a pseudo-steady-state flow stage.

[0019] In the second aspect, the present application also proposes a shale gas well flowback effect evaluation device, the device comprising:

[0020] The first calculation module is used to calculate the equivalent surface total flow rate according to the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas and the volume coefficient of the dimensionless water;

[0021] A curve drawing module is used to calculate the production regularization pressure according to the equivalent total surface flow, the original formation pseudo pressure and the gas well bottom flow pseudo pressure, and draw a relationship curve between the production regularization pressure, the gas well throttle valve size and time during the flowback stage;

[0022] The second calculation module is used to draw a double logarithmic curve of equivalent surface total flow and time when the relationship curve indicates that the gas well productivity is enhanced and the reservoir is improved, and to obtain the comprehensive parameters of the shale gas well according to the double logarithmic curve of equivalent surface total flow and time;

[0023] The determination module is used to establish a corresponding relationship between the comprehensive parameters of the shale gas well and the final recoverable reserves, and determine the type of the shale gas well through the corresponding relationship.

[0024] In a third aspect, the present application further proposes a computer device, comprising a processor and a memory, wherein the memory stores a computer program, and the computer program is loaded and executed by the processor to implement the method for evaluating the shale gas well backflow effect as described in any one of the first aspects.

[0025] In a fourth aspect, the present application further proposes a computer-readable storage medium, in which a computer program is stored. The computer program is loaded and executed by a processor to implement the evaluation method for the backflow effect of a shale gas well as described in any one of the first aspects.

[0026] The above-mentioned main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application; and in the present application, (non-conflicting options) options and other options can also be freely combined. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0027] The present application discloses a method and device for evaluating the flowback effect of a shale gas well, which are applied to a shale gas well. First, an equivalent surface total flow is calculated according to the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas, and the volume coefficient of the dimensionless water. Then, the production regularization pressure is calculated according to the equivalent surface total flow, the original formation pseudo-pressure, and the gas well bottom flow pseudo-pressure. A relationship curve between the production regularization pressure, the gas well throttle valve size, and time in the flowback stage is plotted. When the relationship curve indicates that the gas well production capacity is enhanced and the reservoir is improved, a double logarithmic curve of the equivalent surface total flow and time is plotted. The comprehensive parameters of the shale gas well are obtained according to the double logarithmic curve of the equivalent surface total flow and time. Finally, a corresponding relationship between the comprehensive parameters of the shale gas well and the final recoverable reserves is established. The type of the shale gas well is determined through the corresponding relationship. This can reflect the degree of reservoir improvement after the shale gas well is hydraulically fractured and the effect of the gas well flowback stage is evaluated. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic flow chart of a method for evaluating the flowback effect of a shale gas well proposed in an embodiment of the present application is shown.

[0029] Figure 2 A schematic diagram of the relationship between the normalized pressure of production, the nozzle size and the time provided in the embodiment of the present application is shown.

[0030] Figure 3 A schematic diagram of a double logarithmic curve of equivalent total surface flow and time proposed in an embodiment of the present application is shown.

[0031] Figure 4 A schematic diagram of the relationship between the pressure and time for normalizing the output proposed in the embodiment of the present application is shown.

[0032] Figure 5 Another schematic diagram of the relationship between production normalization pressure, nozzle size and time provided in an embodiment of the present application is shown.

[0033] Figure 6 The relationship curves between production normalization pressure and time, and nozzle size and time are shown.

[0034] Figure 7 A double logarithmic graph of the equivalent total surface flow rate and time for the H1 well is shown.

[0035] Figure 8 The linear flow stage corresponding to the selection of the relationship curves between the normalized pressure and time and the nozzle size and time of the H1 well production is shown.

[0036] Fig. 9 The gas well flowback stage in the well area where the H1 well is located is shown The relationship curve between value and EUR. DETAILED DESCRIPTION

[0037] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0038] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0039] In the prior art, due to the problems of difficult data analysis, insufficient effect evaluation means and lack of timeliness of effect evaluation in the flowback stage of shale gas horizontal wells, in order to solve the above problems, considering the existence of gas-water two-phase flow in the actual shale gas well flowback process, and based on the principle of total equivalent surface flow in multiphase flow, this application proposes a shale gas well flowback effect evaluation method and device, which determines the shale gas well type through the corresponding relationship, can reflect the degree of reservoir improvement after shale gas well fracturing transformation and evaluate the effect of the gas well flowback stage, which is described in detail below.

[0040] Please refer to Figure 1 , Figure 1 The flowchart of a method for evaluating the flowback effect of a shale gas well proposed in an embodiment of the present application is shown. The method is applied to a shale gas well and includes the following steps:

[0041] S100, calculating an equivalent total surface flow rate according to the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas, and the volume coefficient of the dimensionless water.

[0042] In the data processing of the shale gas well flowback stage, according to the instantaneous gas production and instantaneous water production recorded in the hourly period of the shale gas well flowback stage, the total equivalent surface flow of the gas well with hourly recording frequency is calculated through the equivalent surface flow principle. The equivalent surface total flow q tol The calculation formula is: tol =(q g *Bg +q w *B w ) / B g , where q g is the instantaneous gas production at the wellhead of the shale gas well, q w is the instantaneous water production at the wellhead of the shale gas well, B g is the volume coefficient of the dimensionless gas, B w is the volume coefficient of dimensionless water. The unit of instantaneous gas production and water production at the wellhead of shale gas well is m 3 / h, the volume coefficient of dimensionless gas and the volume coefficient of dimensionless water are decimals.

[0043] S200, calculating the production regularization pressure according to the equivalent total surface flow, the original formation pseudo pressure and the gas well bottom flow pseudo pressure, and drawing a relationship curve between the production regularization pressure, the gas well throttle valve size and time in the backflow stage.

[0044] The production normalization pressure can reflect the production capacity of the gas well, and the calculation formula is: Where RNP is the yield normalization pressure, m(p i ) is the original formation pseudo pressure, m(p wf ) is the bottom flow pseudo pressure of the gas well, m(p) represents the gas pseudo pressure, and the unit is MPa2 / (mPa·s). μ represents gas viscosity and z represents gas deviation factor.

[0045] After calculating the production normalization pressure (RNP), the relationship curve between the production normalization pressure (RNP), the size of the gas well throttle valve (nozzle) (CS) and time (t) in the flowback stage is plotted in the rectangular coordinate system to determine the change in the production capacity of the shale gas well and whether the reservoir has been effectively improved. Please refer to Figure 2 , Figure 2 The schematic diagram of the relationship between the production normalization pressure, the nozzle size and time provided in the embodiment of the present application is shown. In the figure, as time changes, the nozzle size also increases accordingly. When the nozzle size increases, the production normalization pressure value corresponding to the backflow data is significantly reduced, indicating that the production capacity of the shale gas well is significantly enhanced. At the same time, the slope of the curve gradually decreases and flattens from ① to ④, and the ordinate intercept b value of the production normalization pressure gradually decreases, indicating that the contact area between the fracture and the matrix increases, effectively improving the reservoir.

[0046] It is worth noting that the relationship curve is depicted by the double-porosity Wattenbarger model of shale gas reservoir seepage, which assumes that the shale gas reservoir is a closed rectangular gas reservoir with multiple symmetrical fractures, in which the horizontal section length of the shale gas well is the width of the gas reservoir and is located in the center of the gas reservoir. The gas flows to the center of the horizontal well, and the gas reservoir is a double-porosity plate model composed of fractures and matrix. The gas well production solution of the double-porosity plate model is: q D represents dimensionless output, dimensionless; t D represents dimensionless time, Dimensionless; A m It represents the area of ​​gas flow from the matrix to the crack, that is, the contact area between the matrix and the crack, m 2 , K m represents the matrix permeability of shale gas reservoir, mD; T represents the formation temperature, °F; φ represents the formation porosity, a decimal; μ represents the gas viscosity, mPa·s; c t Indicates the comprehensive compressibility coefficient of gas, pas -1 .

[0047] S300. When the relationship curve indicates that the gas well productivity is enhanced and the reservoir is improved, a double logarithmic curve of the equivalent surface total flow and time is drawn, and the comprehensive parameters of the shale gas well are obtained based on the double logarithmic curve of the equivalent surface total flow and time.

[0048] Step S300 also includes the following sub-steps: determining the linear flow stage of the shale gas well according to a double logarithmic curve of equivalent surface total flow and time;

[0049] Get the slope value of the linear flow stage;

[0050] The slope value is used in combination with PVT related parameters to calculate the comprehensive parameters of shale gas wells.

[0051] PVT related parameters include formation temperature, formation porosity, gas viscosity and gas comprehensive compressibility coefficient. Please refer to Figure 3 , Figure 3 The schematic diagram of the double logarithmic curve of the equivalent total surface flow and time proposed in the embodiment of the present application is shown, in which the horizontal axis is the logarithmic value of time and the vertical axis is the equivalent total surface flow q tol After the curve is drawn, it is divided into three parts: skin effect stage, linear flow stage and quasi-steady state flow stage. The corresponding slope value (-1 / 2) is obtained through the linear flow stage, and the comprehensive parameters of shale gas wells are determined by combining the slope value with PVT related parameters. Comprehensive parameters of shale gas wells Characterize the conductivity of shale gas wells in the flowback stage, and the calculation formula is: Where T represents the formation temperature, φ represents the formation porosity, m represents the slope value, μ represents the gas viscosity, c t Indicates the comprehensive compression coefficient of gas. To reflect the ultimate recoverable reserves (EUR) and to evaluate the flowback effect of shale gas wells.

[0052] Figure 4 The diagram shows the relationship between the normalized pressure and time of the production proposed in the embodiment of the present application. The deviation from the straight line segment in the skin effect stage is due to the influence of the skin effect of the gas well (the change of streamlines when the gas flows from the shale formation to the wellbore and the additional pressure loss caused by the limited conductive fractures), resulting in an intercept value b between the curve and the ordinate. Therefore, the improvement degree of the shale gas well reservoir can be qualitatively reflected according to the size of the b value. The overall curve of the figure is expressed as:

[0053] S400: Establish a corresponding relationship between comprehensive parameters of shale gas wells and final recoverable reserves, and determine the type of shale gas wells through the corresponding relationship.

[0054] A corresponding relationship (linear) between the comprehensive parameters of shale gas wells and the ultimate recoverable reserves is established. The types of shale gas wells are divided into high-yield wells (greater than 120 million cubic meters), medium-yield wells (between 100 million and 120 million cubic meters) and low-yield wells (less than 100 million cubic meters) according to the ultimate recoverable reserves (EUR). A typical curve chart of high-, medium- and low-yield wells is established. The comprehensive parameters of shale gas wells can directly identify the type of shale gas wells, predict the EUR value of the shale gas well, and realize the rapid evaluation of the flowback effect of shale gas wells.

[0055] Next, the above method is verified by selecting a shale gas well H1 with a horizontal section length of 2000 meters, an original formation pressure Pi of 80MPa, a reservoir temperature T of 296.06℉, a porosity φ of 5.0%, a gas viscosity μ of 0.037mPa·s, a gas deviation factor z of 1.506, a gas volume coefficient of 0.0027, a water volume coefficient of 1.01, and a comprehensive compressibility coefficient of 0.00314Mpa. -1 .

[0056] According to the instantaneous gas production and instantaneous water production recorded in the hourly flowback stage, the total equivalent surface flow rate of the gas well will be obtained through the equivalent flow principle. Combined with the bottom hole pressure data recorded in the hourly flowback stage, as well as parameters such as porosity, gas viscosity, and gas deviation factor, the production normalization pressure data is obtained. For specific analysis data, see Table 1:

[0057] Table 1 H1 well flowback stage data processing table

[0058]

[0059] Figure 5 Another curve diagram of the relationship between the normalized pressure, nozzle size and time provided in the embodiment of the present application is shown. The dark color in the figure represents the normalized pressure, and the light color represents the nozzle size. Figure 6 The relationship curves of production regularization pressure and time, and nozzle size and time are shown. The shaded part indicates that the reservoir fracturing transformation effect of the well is good. When the nozzle size gradually increases, the corresponding RNP value decreases, and the production capacity of the gas well is enhanced. At the same time, the slope of the curve gradually decreases and flattens from ① to ⑥, and the intercept b value of the curve and the RNP ordinate gradually decreases, indicating that the contact area between the fracture and the matrix increases, which effectively improves the reservoir.

[0060] According to S300, Figure 7 The double logarithmic curve of the equivalent total surface flow rate of H1 well and time is shown. Figure 8 The relationship curves between normalized pressure and time, and nozzle size and time of H1 well production are shown. The corresponding linear flow stage (the shaded part in the figure) is selected, and the slope m of the curve in this stage is obtained to be 181.314. According to Obtain the formula and substitute the value of m to obtain the value of The value is 1488m 2 ·mD 1 / 2 ,according to Fig. 9 The gas well flowback stage in the well area where the H1 well is located is shown The relationship curve between the value and EUR can be used to calculate the EUR size of the well. Substituting the value into the relational formula, we can get the EUR value of the well to be 90 million cubic meters, which classifies the well as a low-yield well. The value is used to quantitatively evaluate the flowback effect of gas wells.

[0061] This application is used to carry out the evaluation of the effect of the flowback stage of shale gas wells. By relying on the hourly data of the flowback stage and combining it with the regularized curve, the flowback effect of the gas well can be predicted, providing certain guidance for the evaluation of the development effect of shale gas wells and the optimization of development technology policies.

[0062] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0063] First, based on the principle of equivalent flow, full use of hourly high-frequency data during the flowback stage of shale gas wells can timely and effectively reflect the changes in shale gas well production dynamics over time and the changes in the degree of reservoir improvement during the flowback period.

[0064] Second, the comprehensive parameters of shale gas wells during the flowback stage of shale gas wells can be used to quickly evaluate the final recoverable reserves of the gas wells during the flowback stage of shale gas wells.

[0065] Third, by establishing a shale gas well flowback stage effect evaluation chart for the block, the purpose of classifying and evaluating the flowback effect of shale gas wells in the block and timely assessing the investment risk of gas wells can be achieved.

[0066] A possible implementation of a shale gas well flowback effect evaluation device is provided below, which is used to execute the various execution steps and corresponding technical effects of the shale gas well flowback effect evaluation method shown in the above embodiments and possible implementations. The device includes:

[0067] The first calculation module is used to calculate the equivalent surface total flow rate according to the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas and the volume coefficient of the dimensionless water;

[0068] The curve drawing module is used to calculate the production regularization pressure according to the equivalent total surface flow, the original formation pseudo pressure and the gas well bottom flow pseudo pressure, and draw the relationship curve between the production regularization pressure, the gas well throttle valve size and time in the backflow stage;

[0069] The second calculation module is used to draw a double logarithmic curve of equivalent surface total flow and time when the relationship curve indicates that the gas well productivity is enhanced and the reservoir is improved, and to obtain the comprehensive parameters of the shale gas well according to the double logarithmic curve of equivalent surface total flow and time;

[0070] The determination module is used to establish the corresponding relationship between the comprehensive parameters of the shale gas well and the final recoverable reserves, and determine the type of the shale gas well through the corresponding relationship.

[0071] This preferred embodiment provides a computer device, which can implement the steps in any embodiment of the shale gas well backflow effect evaluation method provided in the embodiments of the present application. Therefore, the beneficial effects of the shale gas well backflow effect evaluation method provided in the embodiments of the present application can be achieved. Please refer to the previous embodiments for details and will not be repeated here.

[0072] Those skilled in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructions, or by controlling related hardware through instructions, and the instructions can be stored in a computer-readable storage medium and loaded and executed by a processor. To this end, an embodiment of the present application provides a storage medium, which stores multiple instructions, and the instructions can be loaded by a processor to execute the steps of any embodiment of the shale gas well backflow effect evaluation method provided in the embodiment of the present application.

[0073] The storage medium may include: a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0074] Since the instructions stored in the storage medium can execute the steps in any embodiment of the evaluation method for the backflow effect of a shale gas well provided in the embodiments of the present application, the beneficial effects that can be achieved by the evaluation of the backflow effect of any shale gas well provided in the embodiments of the present application can be achieved. For details, please refer to the previous embodiments and will not be repeated here.

[0075] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for evaluating the flowback effect of a shale gas well, characterized in that: The method is applied to a shale gas well, comprising: The equivalent total surface flow is calculated based on the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas, and the volume coefficient of the dimensionless water; Calculate the production regularization pressure according to the equivalent total surface flow, the original formation pseudo pressure and the gas well bottom flow pseudo pressure, and draw a relationship curve between the production regularization pressure, the gas well throttle valve size and time during the flowback stage; When the relationship curve indicates that the gas well productivity is enhanced and the reservoir is improved, a double logarithmic curve of equivalent surface total flow and time is drawn, and comprehensive parameters of the shale gas well are obtained according to the double logarithmic curve of equivalent surface total flow and time; A corresponding relationship between the comprehensive parameters of the shale gas well and the final recoverable reserves is established, and the type of the shale gas well is determined based on the corresponding relationship.

2. The evaluation method according to claim 1, wherein: The step of obtaining the comprehensive parameters of the shale gas well according to the double logarithmic curve of the equivalent total surface flow and time includes: Determining the linear flow stage of the shale gas well according to the double logarithmic curve of equivalent total surface flow and time; Obtaining a slope value of the linear flow stage; The slope value is used in combination with PVT related parameters to calculate the comprehensive parameters of the shale gas well.

3. The evaluation method according to claim 2, characterized in that: The PVT related parameters include formation temperature, formation porosity, gas viscosity and gas comprehensive compressibility coefficient, shale gas well comprehensive parameters The calculation formula is: Where T represents the formation temperature, φ represents the formation porosity, m represents the slope value, μ represents the gas viscosity, c t Indicates the comprehensive compressibility factor of gas.

4. The evaluation method according to claim 1, wherein: Equivalent total surface flow q tol The calculation formula is: tol =(q g *B g +q w *B w ) / B g , where q g is the instantaneous gas production at the wellhead of the shale gas well, q w is the instantaneous water production at the wellhead of the shale gas well, B g is the volume coefficient of dimensionless gas, B w is the dimensionless volume coefficient of water.

5. The evaluation method according to claim 1, wherein: The calculation formula for production regularization pressure is: Where RNP is the yield normalization pressure, m(p i ) is the original formation pseudo pressure, m(p wf ) is the pseudo bottom flow pressure of the gas well.

6. The evaluation method according to claim 2, characterized in that: The double logarithmic curve of equivalent total surface flow and time also includes a skin influence stage and a quasi-steady-state flow stage.

7. A device for evaluating the flowback effect of a shale gas well, characterized in that: The device comprises: The first calculation module is used to calculate the equivalent surface total flow rate according to the instantaneous gas production at the wellhead, the instantaneous water production at the wellhead, the volume coefficient of the dimensionless gas and the volume coefficient of the dimensionless water; A curve drawing module is used to calculate the production regularization pressure according to the equivalent total surface flow, the original formation pseudo pressure and the gas well bottom flow pseudo pressure, and draw a relationship curve between the production regularization pressure, the gas well throttle valve size and time during the flowback stage; The second calculation module is used to draw a double logarithmic curve of equivalent surface total flow and time when the relationship curve indicates that the gas well productivity is enhanced and the reservoir is improved, and to obtain the comprehensive parameters of the shale gas well according to the double logarithmic curve of equivalent surface total flow and time; The determination module is used to establish a corresponding relationship between the comprehensive parameters of the shale gas well and the final recoverable reserves, and determine the type of the shale gas well through the corresponding relationship.

8. A computer device, characterized in that: The computer device includes a processor and a memory, wherein a computer program is stored in the memory, and the computer program is loaded and executed by the processor to implement the method for evaluating the shale gas well flowback effect as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, which is loaded and executed by a processor to implement the method for evaluating the flowback effect of a shale gas well as described in any one of claims 1 to 6.

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