Method, device and equipment for evaluating the exploitability conditions of tight gas reservoirs

Abstract

The present invention discloses a method, device and equipment for evaluating the exploitable conditions of a tight gas reservoir, the method comprising: determining the economically recoverable reserves of the gas well based on parameter data of the gas well; evaluating the internal rate of return of the gas well based on a cash flow method to determine the economic limit recoverable reserves of the gas well; evaluating a first risk level of the development of the gas well in the tight gas reservoir based on the economically recoverable reserves and the economic limit recoverable reserves of the gas well; determining a stress sensitivity coefficient of the rock sample in the gas well based on rock sample test data in the gas well; evaluating a second risk level of the development of the gas well in the tight gas reservoir based on the stress sensitivity coefficient and a pre-constructed stress sensitivity productivity curve chart; and / or determining the open flow rate of the gas well using a productivity equation of the gas well based on the stress sensitivity coefficient, parameter data of the gas well and other parameter data of the reservoir, and then evaluating a third risk level of the development of the gas well in the tight gas reservoir, so as to comprehensively evaluate whether there is a risk in the exploitation of the tight gas reservoir.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas reservoir development, and in particular to a method, device and equipment for evaluating the exploitability conditions of a tight gas reservoir. Background Art

[0002] Tight gas reservoirs are defined as natural gas deposits in sandstone formations with permeabilities less than 0.1 millidarcy (mD). As an important natural gas resource, tight gas reservoirs have gradually become a major growth driver of natural gas production. Large-scale tight gas reservoirs, unlike conventional gas reservoirs, typically encompass areas greater than 1,000 square kilometers.

[0003] In actual production, tight gas reservoirs exhibit complex seepage patterns due to low reservoir matrix porosity and permeability, as well as severe heterogeneity. Currently, assessments of tight gas reservoir exploitability primarily consider technically recoverable reserves, which are used to evaluate gas field development outcomes. With the advancement of development and oil companies' increased focus on the economic value of gas field reserves, establishing a rapid assessment method for economically recoverable reserves in tight sandstone gas reservoirs is of great practical significance for guiding the sustainable development of these reservoirs. Summary of the Invention

[0004] In order to enrich process routes and increase selection space, an embodiment of the present invention provides a method, device and equipment for evaluating the exploitable conditions of a tight gas reservoir.

[0005] In a first aspect, an embodiment of the present invention provides a method for evaluating the exploitability conditions of a tight gas reservoir, which may include:

[0006] determining the economically recoverable reserves of the gas well based on the first parameter data of the gas well;

[0007] Evaluate the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well;

[0008] evaluating a first risk level of developing the gas well in the tight gas reservoir based on the economically recoverable reserves of the gas well and the economically limit recoverable reserves of the gas well;

[0009] Determining a stress sensitivity coefficient of the rock sample in the gas well based on rock sample test data in the gas well;

[0010] Based on the stress sensitivity coefficient and a pre-constructed stress sensitivity productivity curve chart, evaluating a second risk level of the gas well in the tight gas reservoir;

[0011] Based on the stress sensitivity coefficient, the second parameter data of the gas well and other parameter data of the reservoir, the open flow rate of the gas well is determined using the productivity equation of the gas well, thereby evaluating the third risk level of the gas well in the tight gas reservoir;

[0012] Based on the first risk level, the second risk level and the third risk level, a comprehensive assessment is made as to whether there is risk in the exploitation of the tight gas reservoir.

[0013] Optionally, determining the economically recoverable reserves of the gas well based on the parameter data of the gas well may include:

[0014] Acquiring first parameter data of the gas well;

[0015] If the first parameter data of the gas well is production data, determining the economically recoverable reserves of the gas well based on the production data and a pre-constructed rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages;

[0016] If the first parameter data of the gas well is production data and static data, determining the economically recoverable reserves of the gas well based on a numerical simulation method;

[0017] The production data include: the full-process pressure in the wellbore, the initial average daily production of the well, the casing pressure before production, the current casing pressure, the average cumulative gas production per well and the gas production per unit pressure drop;

[0018] The static data include: reservoir permeability, reservoir porosity and formation pressure of the gas well.

[0019] Optionally, the gas production per unit pressure drop and recoverable reserves multi-production stage reserves rapid evaluation chart is pre-constructed by the following method:

[0020] Obtain pressure acquisition data and production data of a preset number of produced gas wells;

[0021] Based on the pressure acquisition data and the production data, a unit pressure drop gas production method is used for regression to generate a quick evaluation chart of the unit pressure drop gas production and recoverable reserves in multiple production stages.

[0022] Optionally, the evaluating the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well may include:

[0023] Based on the cash flow method and combined with economic evaluation parameters, the internal rate of return under the current gas price is determined;

[0024] Based on the internal rate of return under the current gas price, a relationship diagram of economically recoverable reserves corresponding to the efficient development of tight gas reservoirs under different gas price conditions is established;

[0025] Based on the current gas price and the economically recoverable reserves relationship diagram corresponding to the efficient development of the tight gas reservoir, the economic limit recoverable reserves of the gas well are determined.

[0026] Optionally, the stress sensitivity production capacity curve chart is pre-constructed according to the following method:

[0027] Obtaining production data of several produced gas wells and pressure sensitivity coefficients of rock samples in the produced gas wells;

[0028] Based on the bottom hole pressure change and gas production in the production data, regression is performed to construct a stress sensitivity production capacity curve chart under different stress sensitivity coefficients.

[0029] Optionally, the second parameter data of the gas well includes: wellbore radius, supply radius and discharge radius;

[0030] Other parameter data of the reservoir include: reservoir permeability, gas layer thickness, skin coefficient, formation temperature, gas relative density, gas viscosity, gas permeability, turbulence coefficient, compressibility, original formation pressure and boundary pressure.

[0031] Optionally, the step of evaluating the third risk level of the gas well in the tight gas reservoir development may further include:

[0032] Adjusting the open flow rate based on an open flow rate error coefficient;

[0033] The open flow error coefficient is determined by comparing the open flow of the gas well determined by the productivity equation of the gas well and the open flow determined by the modified isochronous well test.

[0034] Optionally, the open-flow error coefficient is obtained by the following method:

[0035] Determine the first open flow rate of several produced gas wells based on the modified isochronous well testing method;

[0036] determining a second open flow rate of the plurality of produced gas wells based on a production capacity equation;

[0037] The open flow rate error coefficient is determined based on the first open flow rate and the second open flow rate.

[0038] In a second aspect, an embodiment of the present invention provides a device for evaluating the exploitability conditions of a tight gas reservoir, which may include:

[0039] an economically recoverable reserves determination module, configured to determine the economically recoverable reserves of the gas well based on first parameter data of the gas well;

[0040] A limit economically recoverable reserves determination module is configured to evaluate the internal rate of return of the gas well based on a cash flow method to determine the economic limit recoverable reserves of the gas well;

[0041] A first risk assessment module is configured to assess a first risk level of development of the gas well in the tight gas reservoir based on the economically recoverable reserves of the gas well and the economically limit recoverable reserves of the gas well;

[0042] a stress sensitivity coefficient determination module, configured to determine the stress sensitivity coefficient of the rock sample in the gas well based on the rock sample test data in the gas well;

[0043] A second risk level determination module is configured to evaluate a second risk level of the gas well in the tight gas reservoir development based on the stress sensitivity coefficient and a pre-built stress sensitivity productivity curve chart;

[0044] a third risk level determination module, configured to determine the open flow rate of the gas well using the productivity equation of the gas well based on the stress sensitivity coefficient, the second parameter data of the gas well, and other parameter data of the reservoir, and thereby evaluate a third risk level of the gas well in the tight gas reservoir;

[0045] The risk assessment module is used to comprehensively assess whether there is a risk in the exploitation of the tight gas reservoir based on the first risk level, the second risk level and the third risk level.

[0046] In a third aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method for evaluating the exploitable conditions of a tight gas reservoir as described in the first aspect.

[0047] In a fourth aspect, an embodiment of the present invention provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for evaluating the exploitable conditions of a tight gas reservoir as described in the first aspect is implemented.

[0048] The beneficial effects of the above technical solutions provided by the embodiments of the present invention include at least:

[0049] Embodiments of the present invention provide a method, device, and apparatus for assessing the recoverability of tight gas reservoirs. This method considers the long-term economic development and economic recoverability of gas wells, assessing their long-term productivity based on their economically recoverable reserves. It also evaluates their short-term productivity based on stress sensitivity parameters of rock samples from the wells. This multi-dimensional assessment of the recoverability of a gas well, based on both long-term and short-term productivity, lays the foundation for subsequent engineering deployment and provides a basis for economic development.

[0050] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0051] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0053] Figure 1 This is a flow chart of a method for evaluating the exploitable conditions of a tight gas reservoir provided in an embodiment of the present invention;

[0054] Figure 2 Implementation flowchart for step S11;

[0055] Figure 3 A schematic diagram of pressure data acquisition in gas well generation data provided in an embodiment of the present invention;

[0056] Figure 4 A quick evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages provided in an embodiment of the present invention;

[0057] Figure 5 This is a schematic diagram of economically recoverable reserves determined based on a numerical simulation method provided in an embodiment of the present invention;

[0058] Figure 6 Flowchart for the implementation of step S12;

[0059] Figure 7 A schematic diagram of an internal benefit cash flow established with an IRR of 6% provided in an embodiment of the present invention;

[0060] Figure 8 A relationship diagram of economically recoverable reserves corresponding to efficient development of tight gas under different gas price conditions provided in an embodiment of the present invention;

[0061] Figure 9 A schematic diagram of a stress sensitivity curve provided in an embodiment of the present invention;

[0062] Figure 10 A production capacity curve chart considering stress sensitivity provided in an embodiment of the present invention;

[0063] Figure 11 A schematic diagram of the development of a gas well in a tight gas reservoir provided in an embodiment of the present invention;

[0064] Figure 12 This is a schematic structural diagram of a device for evaluating the exploitability conditions of a tight gas reservoir provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0065] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0066] The inventors discovered during actual production that, when assessing the recoverability of tight gas reservoirs, they failed to fully consider the long-term economic benefits and economic value of the gas wells. Furthermore, due to the low porosity and permeability of the tight gas reservoir matrix and the severe heterogeneity, which leads to complex seepage patterns, the stress sensitivity parameters that influence gas well productivity evaluation were not incorporated into the assessment of the short-term productivity of the gas wells, making it impossible to effectively evaluate the short-term productivity of the gas wells. To address these technical issues, the inventors of this application innovatively proposed the present invention.

[0067] In the embodiment of the present invention, a method for evaluating the exploitable conditions of a tight gas reservoir is provided. Figure 1 As shown, the method may include the following steps:

[0068] Step S11: Determine the economically recoverable reserves of the gas well based on the first parameter data of the gas well.

[0069] Step S12: Evaluate the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well.

[0070] Step S13: Evaluate the first risk level of the gas well in developing the tight gas reservoir based on the economically recoverable reserves and the economically limit recoverable reserves of the gas well.

[0071] In the above steps S11 to S13 in the embodiment of the present invention, the inventors fully consider the long-term economic benefits of the gas well, and evaluate the long-term productivity of the gas well based on the economic limit recoverable reserves to assess whether the gas well is suitable for development in the tight gas reservoir.

[0072] Step S14: Determine the stress sensitivity coefficient of the rock sample in the gas well based on the rock sample test data in the gas well.

[0073] Step S15: Evaluate the second risk level of the gas well in developing the tight gas reservoir based on the stress sensitivity coefficient and the pre-constructed stress sensitivity productivity curve chart.

[0074] Step S16: Based on the stress sensitivity coefficient, the second parameter data of the gas well and other parameter data of the reservoir, the open flow rate of the gas well is determined using the gas well productivity equation, thereby evaluating the third risk level of the gas well in the tight gas reservoir development.

[0075] In steps S14 to S16 of the embodiment of the present invention, the inventors use different methods to evaluate the short-term productivity of the gas well based on the stress sensitivity parameters of the rock samples in the gas well, and assess whether the gas well is exploitable from another dimension.

[0076] It should be noted that, in the embodiment of the present invention, the above steps S11 to S13 are based on the long-term productivity evaluation of the gas well, and steps S14 to S16 are based on the short-term productivity evaluation. The execution order is not specific, and steps S11 to S13 may be executed first, and then steps S14 to S16; or steps S14 to S16 may be executed first, and then steps S11 to S13; or the above steps may be executed simultaneously, and the embodiment of the present invention does not make any specific restrictions on this.

[0077] Step S17: Based on the first risk level, the second risk level, and the third risk level, comprehensively assess whether there is risk in the exploitation of tight gas reservoirs.

[0078] In the method for assessing the recoverability of tight gas reservoirs provided in the embodiments of the present invention, the inventors fully consider the long-term economic development and economic recoverability of gas wells. They then assess the long-term productivity of gas wells based on the economic limit of recoverable reserves. They also evaluate the short-term productivity of gas wells using stress sensitivity parameters of rock samples from the gas wells. This multi-dimensional assessment of gas well recoverability, based on both long-term and short-term productivity, lays the foundation for subsequent engineering deployment and provides a basis for economic development.

[0079] In a specific embodiment, also referring to Figure 1 As shown, the method may include the following steps:

[0080] Step S11: Determine the economically recoverable reserves of the gas well based on the first parameter data of the gas well.

[0081] Before executing this step, the parameter data of the gas well must first be collected. Then, based on the parameter data, the economically recoverable reserves of the gas well are determined in different ways.

[0082] When implementing this step, refer to Figure 2 As shown, the following steps may be included:

[0083] Step S111: Acquire parameter data of the gas well.

[0084] In general, the pressure of the wellbore can be collected by installing a pressure sensor downhole and monitoring the wellbore pressure in real time. Alternatively, the wellbore pressure can be measured throughout the entire process using logging equipment after the wellhead is closed. Figure 3 ). At the same time, a preliminary statistical analysis is conducted on the formation pressure and permeability of the tight gas reservoirs of the oil and gas wells, as well as the average daily production of the oil and gas wells, the casing pressure before production, the current casing pressure, the average cumulative gas production of the wells, and the gas production per unit pressure drop. This statistical analysis needs to be carried out within a certain time frame. The specific time depends on factors such as the production and production history of the oil and gas wells, and is generally controlled within more than 3 months of gas well production. Figure 3 As shown in Table 1, the parameter data of the gas well are obtained.

[0085] Table 1 Development indicator statistics

[0086]

[0087] Step S112: Determine the data type of the first parameter of the gas well. If the first parameter data of the gas well is production data, execute step S113; if the parameter data of the well is production data and static data, execute step S114.

[0088] Among them, production data include: full-process pressure in the wellbore, initial average daily production per well, casing pressure before production, current casing pressure, average cumulative gas production per well and gas production per unit pressure drop; static data include: reservoir permeability, reservoir porosity and formation pressure of the gas well.

[0089] Step S113: Determine the economically recoverable reserves of the gas well based on the production data and a pre-built rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages.

[0090] The rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages in this step is pre-constructed by the following method: first, the pressure acquisition data and production data of a preset number of produced gas wells are obtained; then, the gas production per unit pressure drop method is used to perform regression based on the pressure acquisition data and production data to generate a rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages.

[0091] If a gas well only has production dynamic data and lacks geological data, it is difficult to calculate the recoverable reserves through numerical simulation based on software. Therefore, in the embodiment of the present invention, the inventors evaluate the economically recoverable reserves by establishing a rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages. This chart is an empirical chart formed by regression of production data collected from 150 gas wells in the Ordos Basin and the Songliao Basin in the Sichuan Basin, totaling 450 gas wells. Figure 4 The following is an example of a chart generated based on the above data.

[0092] The primary methods used are pressure acquisition data and production data, specifically the unit pressure drop gas production method, which calculates reserves based on the relationship between reservoir pressure and production. Generally, after a period of reservoir production (approximately 10% recovery), this chart can be used for rapid evaluation. The unit pressure drop gas production and recoverable reserves rapid evaluation chart for multiple production phases evaluates economically recoverable reserves. Therefore, for reservoirs with complex geological structures where accurate gas storage space cannot be determined, such as fractured carbonate reservoirs, the unit pressure drop gas production method is the best choice for calculating natural gas reserves.

[0093] It's important to note that the rapid assessment chart requires the entire reservoir to be interconnected when calculating reserves. If a reservoir is divided into several disconnected hydrodynamic systems due to faults or lithologic pinch-outs, reserves calculations should be performed separately for each system; otherwise, erroneous results will be obtained.

[0094] Step S114: Determine the economically recoverable reserves of the gas well based on a numerical simulation method.

[0095] Reserve parameters usually include geological reserves, recoverable reserves, and cumulative gas production of oil and gas wells. These parameters are very important for evaluating the exploitable conditions of tight gas reservoirs. Among them, geological reserves usually refer to the total amount of mineralized materials in the reservoir, and recoverable reserves refer to the part that can be reasonably mined under current technical conditions. It is equal to the product of geological reserves and recovery rate. Figure 5 As shown, recoverable reserves can be evaluated through numerical simulation software.

[0096] Step S12: Evaluate the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well.

[0097] When implementing this step, refer to Figure 6 As shown, the following steps may be included:

[0098] Step S121: Determine the internal rate of return under the current gas price based on the cash flow method and in combination with economic evaluation parameter indicators.

[0099] First, based on the cash flow method and combined with economic evaluation parameters, the development indicators of gas wells under different gas prices and different internal rates of return are calculated, as shown in Table 2 below:

[0100] Table 2 Values ​​of main parameters of economic evaluation

[0101]

[0102]

[0103] Reference Figure 7Figure 2 shows a schematic diagram of the internal benefit cash flow established for an IRR of 6%.

[0104] Step S122: Based on the internal rate of return under the current gas price, establish a relationship diagram of economically recoverable reserves corresponding to the efficient development of tight gas reservoirs under different gas price conditions. Figure 8 The figure shows the economically recoverable reserves relationship diagram corresponding to the efficient development of tight gas under the same gas price conditions (internal rate of return 6%).

[0105] Step S123: Determine the economic limit recoverable reserves of the gas well based on the current gas price and the economic recoverable reserves relationship diagram corresponding to the efficient development of tight gas reservoirs.

[0106] from Figure 8 It can be analyzed that when the economic limit recoverable reserves of a gas well is 42.5 million cubic meters, the internal rate of return of the gas well reaches 6%. If the recoverable reserves of a gas well can be calculated using numerical simulation methods, the evaluation effect of the gas well and the well area can be directly determined. If the gas well only has production data, the evaluation can be performed by comparing the unit pressure drop gas production with the recoverable reserves multi-production stage reserve rapid evaluation chart. For example, if the unit pressure drop gas production reaches 1.8 million cubic meters / MPa after 300 days of production, the gas reservoir is worthy of continued development; otherwise, the development risk is relatively high. That is, in this embodiment, the economic limit recoverable reserves of the gas well is 42.5 million cubic meters. By comparing this with the economic recoverable reserves of the gas well obtained in step S11 above, the first risk level of the gas well development in this tight gas reservoir can be assessed.

[0107] Step S13: Evaluate the first risk level of the gas well in developing the tight gas reservoir based on the economically recoverable reserves and the economically limit recoverable reserves of the gas well.

[0108] Step S14: Determine the stress sensitivity coefficient of the rock sample in the gas well based on the rock sample test data in the gas well.

[0109] The inventors found that stress sensitivity is the main factor affecting the evaluation of gas well productivity. Therefore, establishing a gas phase seepage model and productivity equation that considers stress sensitivity to more accurately obtain the productivity of gas wells in tight gas reservoirs is a problem that needs to be studied currently.

[0110] Due to the complexity of tight gas reservoirs, a significant feature of tight gas reservoirs is stress sensitivity, which has a great impact on gas well productivity. As the development of oil and gas fields progresses, the reservoir pore pressure gradually decreases, which leads to changes in the effective stress of the rock, and then changes in the reservoir formation parameter characteristics. Figure 9As shown in the figure, laboratory studies of stress sensitivity under various reservoir conditions reveal that stress sensitivity is quite strong when permeability is less than 0.1 mD. In the later stages of development, permeability loss can reach over 70%. This indicates that stress sensitivity in tight sandstone gas reservoirs has a significant impact on reservoir gas well productivity.

[0111] Therefore, if dynamic and static data of gas wells are collected together with test data of rock samples, the development effect of the gas wells in the block can be determined based on the production capacity equation that considers stress sensitivity, and future development risks can be effectively assessed.

[0112] Step S15: Evaluate the second risk level of the gas well in developing the tight gas reservoir based on the stress sensitivity coefficient and the pre-constructed stress sensitivity productivity curve chart.

[0113] The stress sensitivity yield curve chart in this step is pre-built according to the following method:

[0114] First, production data from several existing gas wells and the pressure sensitivity coefficients of rock samples from these wells were obtained. Then, based on the bottomhole pressure changes and gas production in the production data, regression was performed to construct stress sensitivity production capacity curves under different stress sensitivity coefficients.

[0115] Reference Figure 10 As shown in the figure, through laboratory analysis and evaluation of reservoir rock stress sensitivity, combined with the collection of formation pressure data and chart analysis, it is judged whether the gas reservoir can be developed. In the actual development of tight gas reservoirs, if the stress sensitivity value is greater than 0.7, it will have a greater impact on the final result of the gas well production capacity and the development risk is greater.

[0116] Step S16: Based on the stress sensitivity coefficient, the second parameter data of the gas well, and other reservoir parameter data, the gas well's open flow rate is determined using the gas well's productivity equation, thereby assessing the third risk level of the gas well in the tight gas reservoir. The second parameter data of the gas well includes: wellbore radius, supply radius, and discharge radius; the other reservoir parameter data includes: reservoir permeability, gas layer thickness, skin coefficient, formation temperature, gas relative density, gas viscosity, gas permeability, turbulence coefficient, compressibility, original formation pressure, and boundary pressure.

[0117] When executing this step, first establish the seepage model of the tight gas reservoir, perform correlation analysis on the formation pressure and gas production; and determine the feasibility of development assessment based on the correlation between formation pressure and gas production. Figure 11As shown in the figure, the mathematical model is established with the following assumptions: 1) The reservoir is isotropic and divided into two regions: the outer region has dense sandstone, low permeability, and the gas-water two-phase flow is elliptical, and dissolved gas is not considered; the inner region has vertical fractures that are symmetrically distributed along both sides of the wellbore and have limited conductivity, and the gas seepage in the fractures considers the non-Darcy effect; 2) the stress sensitivity of the reservoir is considered, that is, the permeability will decrease with the decrease of formation pressure.

[0118] The specific calculation process of this step through the gas well productivity equation is as follows:

[0119] The equation of motion for a gas is:

[0120] Pseudo-pressure equation:

[0121] Gas production equation:

[0122] in, μ g —Gas viscosity; k i —initial permeability; k rg —gas permeability; q g —gas production; p wf —bottom hole pressure; q sc —output under standard conditions; r e —Discharge radius; r w —wellbore radius; S—skin coefficient; D—turbulence coefficient; T—temperature; h—thickness; α—stress sensitivity coefficient; Z—compression coefficient; p i - original formation pressure; p e -Boundary pressure.

[0123] This formula accounts for the influence of stress sensitivity during gas flow in a reservoir. Theoretical analysis shows that in tight sandstone gas reservoirs, the open-flow rate and maximum flow rate of a gas well decrease with increasing stress sensitivity. Furthermore, the impact of stress sensitivity on production increases as bottomhole pressure decreases. The theoretical chart developed using the above formula, which accounts for stress sensitivity, agrees well with actual production. Furthermore, well productivity results are highly correlated with stress sensitivity, decreasing with increasing stress sensitivity. Using this productivity formula, given known parameters such as formation pressure, permeability, gas layer thickness, wellbore radius, supply radius, skin coefficient, formation temperature, and relative gas density, the productivity of a gas well accounting for stress sensitivity can be calculated. The calculated results are within 2% of those calculated using the software, reducing costs.

[0124] In another optional embodiment, evaluating the third risk level of the gas well in the tight gas reservoir development also includes: adjusting the open flow rate based on the open flow rate error coefficient; wherein the open flow rate error coefficient is determined by comparing the open flow rate of the gas well determined by the production capacity equation of the gas well and the open flow rate determined by the modified isochronous well test method.

[0125] In another optional embodiment, the open-flow rate error coefficient is obtained specifically by the following method: first, the first open-flow rate of several produced gas wells is determined based on the modified isochronous well testing method; and the second open-flow rate of several produced gas wells is determined based on the production capacity equation; then, based on the first open-flow rate and the second open-flow rate, the open-flow rate error coefficient is determined.

[0126] As shown in Table 3, the error between the production capacity determined based on the existing modified isochronous well testing method and the production capacity determined based on the above-mentioned production capacity formula provided in the embodiment of the present invention is controllable, and the open flow rate determined by the above-mentioned method can be corrected by using this error.

[0127] Table 3 Comparison of calculation results between the formula method and the modified isochronous well test method

[0128]

[0129] Step S17: Based on the first risk level, the second risk level, and the third risk level, comprehensively assess whether there is risk in the exploitation of tight gas reservoirs.

[0130] In the methods for assessing the recoverability of tight gas reservoirs provided in the embodiments of the present invention, the inventors fully consider the long-term economic development and economic recoverability of gas wells. They then assess the long-term productivity of gas wells based on the economic limit of recoverable reserves. They also evaluate the short-term productivity of gas wells using stress sensitivity parameters of rock samples from the gas wells. This multi-dimensional assessment of the recoverability of gas wells, based on both long-term and short-term productivity, yields the recoverable reserves and productivity of the appraisal wells. These two indicators can be used to determine whether the development of the gas reservoir in which the appraisal well is located is risky and whether sustainable development is feasible, laying the foundation for subsequent engineering deployment and providing a basis for economic development.

[0131] Based on the same inventive concept, an evaluation device for the exploitable conditions of a tight gas reservoir is also provided in an embodiment of the present invention. Figure 12 As shown, the device may include: an economically recoverable reserves determination module 11, a limit economically recoverable treatment determination module 12, a first risk level assessment module 13, a stress sensitivity coefficient determination module 14, a second risk level determination module 15, a third risk level determination module 16, and a risk assessment module 17. Its working principle is as follows:

[0132] The economically recoverable reserves determination module 11 is used to determine the economically recoverable reserves of the gas well based on the first parameter data of the gas well;

[0133] The economic limit recoverable reserves determination module 12 is used to evaluate the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well;

[0134] The first risk level assessment module 13 is used to assess the first risk level of the gas well development in the tight gas reservoir based on the economically recoverable reserves and the economically limit recoverable reserves of the gas well;

[0135] The stress sensitivity coefficient determination module 14 is used to determine the stress sensitivity coefficient of the rock sample in the gas well based on the rock sample test data in the gas well;

[0136] The second risk level determination module 15 is used to evaluate the second risk level of the gas well development in the tight gas reservoir based on the stress sensitivity coefficient and the pre-built stress sensitivity productivity curve chart;

[0137] The third risk level determination module 16 is configured to determine the open flow rate of the gas well using the gas well productivity equation based on the stress sensitivity coefficient, the second parameter data of the gas well, and other parameter data of the reservoir, thereby evaluating the third risk level of the gas well in the tight gas reservoir development.

[0138] The comprehensive risk assessment module 17 is used to assess whether there is risk in the exploitation of tight gas reservoirs based on the first risk level, the second risk level and the third risk level.

[0139] In an optional embodiment, the economically recoverable reserves determination module 11 is specifically configured to:

[0140] Acquiring first parameter data of the gas well;

[0141] If the first parameter data of the gas well is production data, determining the economically recoverable reserves of the gas well based on the production data and a pre-constructed rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages;

[0142] If the first parameter data of the gas well is production data and static data, determining the economically recoverable reserves of the gas well based on a numerical simulation method;

[0143] The production data include: the full-process pressure in the wellbore, the initial average daily production of the well, the casing pressure before production, the current casing pressure, the average cumulative gas production per well and the gas production per unit pressure drop;

[0144] The static data include: reservoir permeability, reservoir porosity and formation pressure of the gas well.

[0145] In another alternative embodiment, referring to Figure 12As shown, the device may further include: a rapid evaluation chart construction module 18, which is used to:

[0146] Obtain pressure acquisition data and production data of a preset number of produced gas wells;

[0147] Based on the pressure acquisition data and the production data, a unit pressure drop gas production method is used for regression to generate a quick evaluation chart of the unit pressure drop gas production and recoverable reserves in multiple production stages.

[0148] In another optional embodiment, the limit economically recoverable treatment determination module 12 is specifically configured to:

[0149] Based on the cash flow method and combined with economic evaluation parameters, the internal rate of return under the current gas price is determined;

[0150] Based on the internal rate of return under the current gas price, a relationship diagram of economically recoverable reserves corresponding to the efficient development of tight gas reservoirs under different gas price conditions is established;

[0151] Based on the current gas price and the economically recoverable reserves relationship diagram corresponding to the efficient development of the tight gas reservoir, the economic limit recoverable reserves of the gas well are determined.

[0152] In another alternative embodiment, referring to Figure 12 As shown, the device may further include: a stress sensitivity capacity curve plate construction module 19, which is specifically used to:

[0153] Obtaining production data of several produced gas wells and pressure sensitivity coefficients of rock samples in the produced gas wells;

[0154] Based on the bottom hole pressure change and gas production in the production data, regression is performed to construct a stress sensitivity production capacity curve chart under different stress sensitivity coefficients.

[0155] In another alternative embodiment, referring to Figure 12 As shown, the device may also include: an adjustment module 20, used to adjust the open-flow rate based on an open-flow rate error coefficient; wherein the open-flow rate error coefficient is determined by comparing the open-flow rate of the gas well determined by the production capacity equation of the gas well and the open-flow rate determined by the modified isochronous well test method.

[0156] In another optional embodiment, the open-flow error coefficient in the adjustment module 20 is determined according to the following method:

[0157] Determine the first open flow rate of several produced gas wells based on the modified isochronous well testing method;

[0158] determining a second open flow rate of the plurality of produced gas wells based on a production capacity equation;

[0159] The open flow rate error coefficient is determined based on the first open flow rate and the second open flow rate.

[0160] Based on the same inventive concept, an embodiment of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the above-mentioned method for evaluating the exploitable conditions of a tight gas reservoir is implemented.

[0161] Based on the same inventive concept, an embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the program, the above-mentioned method for evaluating the exploitable conditions of tight gas reservoirs is implemented.

[0162] The principles of the problems solved by the above-mentioned devices, media, and related equipment in the embodiments of the present invention are similar to those of the above-mentioned methods. Therefore, their implementation can refer to the implementation of the above-mentioned methods, and the repeated parts will not be repeated.

[0163] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0164] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0165] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0166] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0167] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for evaluating the exploitability of tight gas reservoirs, characterized in that: include: determining the economically recoverable reserves of the gas well based on the first parameter data of the gas well; Evaluate the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well; evaluating a first risk level of developing the gas well in the tight gas reservoir based on the economically recoverable reserves of the gas well and the economically limit recoverable reserves of the gas well; Determining a stress sensitivity coefficient of the rock sample in the gas well based on rock sample test data in the gas well; Based on the stress sensitivity coefficient and a pre-constructed stress sensitivity productivity curve chart, evaluating a second risk level of the gas well in the tight gas reservoir; Based on the stress sensitivity coefficient, the second parameter data of the gas well and other parameter data of the reservoir, the open flow rate of the gas well is determined using the productivity equation of the gas well, thereby evaluating the third risk level of the gas well in the tight gas reservoir; Based on the first risk level, the second risk level and the third risk level, a comprehensive assessment is made as to whether there is risk in the exploitation of the tight gas reservoir.

2. The method according to claim 1, characterized in that Determining the economically recoverable reserves of the gas well based on the first parameter data of the gas well includes: Acquiring first parameter data of the gas well; If the first parameter data of the gas well is production data, determining the economically recoverable reserves of the gas well based on the production data and a pre-constructed rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages; If the first parameter data of the gas well is production data and static data, determining the economically recoverable reserves of the gas well based on a numerical simulation method; The production data include: the full-process pressure in the wellbore, the initial average daily production of the well, the casing pressure before production, the current casing pressure, the average cumulative gas production per well and the gas production per unit pressure drop; The static data include: reservoir permeability, reservoir porosity and formation pressure of the gas well.

3. The method according to claim 2, characterized in that The rapid evaluation chart of gas production per unit pressure drop and recoverable reserves in multiple production stages is pre-constructed by the following method: Obtain pressure acquisition data and production data of a preset number of produced gas wells; Based on the pressure acquisition data and the production data, a unit pressure drop gas production method is used for regression to generate a quick evaluation chart of the unit pressure drop gas production and recoverable reserves in multiple production stages.

4. The method according to claim 1, wherein The evaluation of the internal rate of return of the gas well based on the cash flow method to determine the economic limit recoverable reserves of the gas well includes: Based on the cash flow method and combined with economic evaluation parameters, the internal rate of return under the current gas price is determined; Based on the internal rate of return under the current gas price, a relationship diagram of economically recoverable reserves corresponding to the efficient development of tight gas reservoirs under different gas price conditions is established; Based on the current gas price and the economically recoverable reserves relationship diagram corresponding to the efficient development of the tight gas reservoir, the economic limit recoverable reserves of the gas well are determined.

5. The method according to claim 1, characterized in that The stress sensitivity capacity curve chart is pre-constructed according to the following method: Obtaining production data of several produced gas wells and pressure sensitivity coefficients of rock samples in the produced gas wells; Based on the bottom hole pressure change and gas production in the production data, regression is performed to construct a stress sensitivity production capacity curve chart under different stress sensitivity coefficients.

6. The method according to claim 1, characterized in that The second parameter data of the gas well includes: wellbore radius, supply radius and discharge radius; Other parameter data of the reservoir include: reservoir permeability, gas layer thickness, skin coefficient, formation temperature, gas relative density, gas viscosity, gas permeability, turbulence coefficient, compressibility, original formation pressure and boundary pressure.

7. The method according to claim 1, characterized in that The evaluating of the third risk level of the gas well development in the tight gas reservoir further includes: Adjusting the open flow rate based on an open flow rate error coefficient; The open flow error coefficient is determined by comparing the open flow of the gas well determined by the productivity equation of the gas well and the open flow determined by the modified isochronous well test.

8. The method according to claim 7, characterized in that The open-flow error coefficient is specifically obtained by the following method: Determine the first open flow rate of several produced gas wells based on the modified isochronous well testing method; determining a second open flow rate of the plurality of produced gas wells based on a production capacity equation; The open flow rate error coefficient is determined based on the first open flow rate and the second open flow rate.

9. A device for evaluating the exploitability of tight gas reservoirs, characterized in that: include: an economically recoverable reserves determination module, configured to determine the economically recoverable reserves of the gas well based on first parameter data of the gas well; A limit economically recoverable reserves determination module is configured to evaluate the internal rate of return of the gas well based on a cash flow method to determine the economic limit recoverable reserves of the gas well; A first risk assessment module is configured to assess a first risk level of development of the gas well in the tight gas reservoir based on the economically recoverable reserves of the gas well and the economically limit recoverable reserves of the gas well; a stress sensitivity coefficient determination module, configured to determine the stress sensitivity coefficient of the rock sample in the gas well based on the rock sample test data in the gas well; A second risk level determination module is configured to evaluate a second risk level of the gas well in the tight gas reservoir development based on the stress sensitivity coefficient and a pre-built stress sensitivity productivity curve chart; a third risk level determination module, configured to determine the open flow rate of the gas well using the productivity equation of the gas well based on the stress sensitivity coefficient, the second parameter data of the gas well, and other parameter data of the reservoir, and thereby evaluate a third risk level of the gas well in the tight gas reservoir; The comprehensive risk assessment module is used to comprehensively assess whether there is a risk in the exploitation of the tight gas reservoir based on the first risk level, the second risk level and the third risk level.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method for evaluating the exploitable conditions of a tight gas reservoir according to any one of claims 1 to 8 is implemented.

11. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method for evaluating the exploitable conditions of a tight gas reservoir according to any one of claims 1 to 8 is implemented.

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