Method and device for determining porosity of gas-bearing tight sandstone reservoir and storage medium

Abstract

The embodiment of the invention provides a method and device for determining the porosity of a gas-bearing tight sandstone reservoir and a storage medium, and belongs to the technical field of mine field geophysical logging and oil and gas field exploration. The determination method comprises the steps that a first calculation model for the porosity of the gas-bearing tight sandstone reservoir is established based on model parameters related to the porosity of the gas-bearing tight sandstone reservoir, and the model parameters comprise density porosity, neutron porosity and related weight coefficients; the weight coefficient is used for representing the influence degree of natural gas contained in the gas-bearing tight sandstone reservoir on the density porosity and the neutron porosity; and obtaining the porosity of the gas-bearing tight sandstone reservoir based on the established first calculation model. According to the embodiment of the invention, the weight coefficient is introduced, so that the influence of reservoir gas content on the porosity is reduced, the accuracy of compact sandstone reservoir porosity calculation is further improved, and more accurate data support is provided for subsequent reserve calculation and development decision.

Description

Technical Field

[0001] The invention relates to the technical field of mine geophysical logging and oil and gas field exploration, and in particular to a method, a device and a storage medium for determining the porosity of a gas-bearing tight sandstone reservoir. Background Art

[0002] At present, the porosity of tight sandstone reservoirs is mainly determined by single porosity logging curves or neutron-density intersection methods. However, by comparing the porosity of core analysis with the porosity calculated by logging, it is found that the porosity calculated by the above methods in the water layer section and the oil layer section is slightly different, and the error meets the calculation specifications. However, when the reservoir contains gas, the porosity calculated by the acoustic time difference and the compensated neutron is significantly smaller than the core analysis value, and the porosity calculated by density is greater than the core analysis value. When the neutron-density intersection method is used to calculate the porosity, when the porosity is small, the logging calculation and the core analysis value are in good agreement, and when the porosity is relatively large, the error increases significantly. The reason is that the influence of the pore development degree and reservoir fluid on the porosity logging is not considered, and the calculation accuracy is difficult to control, which further leads to a large error in the comparison of reservoir porosity and core analysis. Summary of the invention

[0003] The purpose of the embodiments of the present invention is to provide a method, device and storage medium for determining the porosity of a gas-bearing tight sandstone reservoir, so as to at least partially solve the above-mentioned technical problems.

[0004] In order to achieve the above-mentioned objectives, in first aspect, an embodiment of the present invention provides a method for determining the porosity of a gas-bearing tight sandstone reservoir, the determination method comprising: establishing a first calculation model for the porosity of the gas-bearing tight sandstone reservoir based on model parameters related to the porosity of the gas-bearing tight sandstone reservoir, wherein the model parameters include density porosity, neutron porosity and associated weight coefficients, and the weight coefficients are used to characterize the degree of influence of the natural gas contained in the gas-bearing tight sandstone reservoir on the density porosity and the neutron porosity; and obtaining the porosity of the gas-bearing tight sandstone reservoir based on the established first calculation model.

[0005] Optionally, the first calculation model for the porosity of the gas-bearing tight sandstone reservoir is characterized by the following formula:

[0006] φ=φN×p n +φD×(1-p n )

[0007] Wherein, φ is the porosity of the gas-bearing tight sandstone reservoir, p n is the weight coefficient, φ D is the density porosity of the gas-bearing tight sandstone reservoir, φ N is the neutron porosity of the gas-bearing tight sandstone reservoir.

[0008] Optionally, the density porosity φ D It is determined using the following formula:

[0009]

[0010] Wherein, ρ is the density logging value of the gas-bearing tight sandstone reservoir, ρ ma is the rock skeleton value of the gas-bearing tight sandstone reservoir, ρ f is the formation fluid density of the gas-bearing tight sandstone reservoir, V sh is the shale content of the gas-bearing tight sandstone reservoir, ρ sh is the mudstone density value of the gas-bearing tight sandstone reservoir.

[0011] Optionally, the neutron porosity φ N It is determined using the following formula:

[0012] φ N =CNL-φ Nma -V sh φ sh

[0013] Wherein, CNL is the neutron logging value of the gas-bearing tight sandstone reservoir, φ Nma is the neutron skeleton value of the gas-bearing tight sandstone reservoir, φ sh is the mudstone neutron value of the gas-bearing tight sandstone reservoir.

[0014] Optionally, the associated weight coefficient is determined based on the following steps: based on the core analysis porosity of the gas-bearing tight sandstone reservoir, establishing a second calculation model for the weight coefficient, wherein the second calculation model is configured to characterize the changing relationship between the weight coefficient and the core analysis porosity; based on the second calculation model, determining the weight coefficient.

[0015] Optionally, the establishment of a second calculation model for the weight coefficient includes: assigning values ​​to the weight coefficients in the first calculation model in sequence based on the assignment interval and assignment gradient of the weight coefficients to obtain the corresponding first porosity of the gas-bearing tight sandstone reservoir; comparing the first porosity with the core analysis porosity, and when the two are consistent, determining that the assignment of the weight coefficient corresponding to the first porosity is the assignment of the weight coefficient corresponding to the core analysis porosity; fitting all core analysis porosities with the assignments of their corresponding weight coefficients to obtain a fitting curve characterizing the relationship between the corresponding weight coefficients and the core analysis porosity, so as to establish the calculation model of the weight coefficient based on the fitting curve.

[0016] Optionally, the determination method also includes determining the core analysis porosity of the gas-bearing tight sandstone reservoir, which includes: obtaining the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir based on the neutron porosity and the density porosity of the gas-bearing tight sandstone reservoir, and using the neutron-density intersection porosity as the core analysis porosity.

[0017] Optionally, the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir is obtained by using the following formula:

[0018]

[0019] Among them, φ DN is the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir, φ D is the density porosity of the gas-bearing tight sandstone reservoir, φ N is the neutron porosity of the gas-bearing tight sandstone reservoir.

[0020] In a second aspect, an embodiment of the present invention provides a device for determining the porosity of a gas-bearing tight sandstone reservoir, characterized in that the device comprises: a memory storing a program that can be run on a processor; and the processor being configured to implement the method for determining the porosity of a gas-bearing tight sandstone reservoir described in the first aspect when executing the program.

[0021] In a third aspect, an embodiment of the present invention provides a machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the method for determining the porosity of a gas-bearing tight sandstone reservoir as described in the first aspect of the present application.

[0022] Through the above technical solution, the weight coefficient is introduced to effectively reduce the impact of reservoir gas content on porosity, thereby improving the accuracy of porosity calculation for tight sandstone reservoirs, thereby providing more accurate data support for subsequent reserve calculations and development decisions.

[0023] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0025] Figure 1 It is a schematic flow chart of a method for determining the porosity of a gas-bearing tight sandstone reservoir according to an exemplary embodiment;

[0026] Figure 2is a flow chart of a method for determining a parameter value of a weight coefficient according to an exemplary embodiment;

[0027] Figure 3 is a flow chart of a method for establishing a calculation model for weight coefficients according to an exemplary embodiment;

[0028] Figure 4 is a schematic diagram of a curve reflecting the variation law of weight coefficient with core analysis porosity according to an exemplary embodiment;

[0029] Figure 5 is a schematic diagram showing a comparison of calculation results of porosity obtained by using neutron, density, neutron-density intersection and weight coefficient method according to an exemplary embodiment;

[0030] Figure 6 is a schematic diagram showing a comparison between the porosity obtained by neutron-density intersection method and the porosity obtained by core analysis according to an exemplary embodiment; and

[0031] Figure 7 It is a schematic diagram showing a comparison between the porosity obtained by using a weight coefficient method and the porosity obtained by core analysis according to an exemplary embodiment. DETAILED DESCRIPTION

[0032] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0033] First, some terms involved in the embodiments of the present invention are introduced and explained here so that those skilled in the art can understand the technical solutions of the present invention.

[0034] 1. Tight sandstone reservoir refers to a sandstone reservoir with low reservoir permeability. Compared with conventional sandstone reservoirs, it has the typical characteristics of dense lithology, low porosity and low permeability, low gas reservoir pressure coefficient, low closure amplitude, and low natural production capacity, and is relatively difficult to exploit.

[0035] 2. The porosity of gas-bearing tight sandstone reservoirs, i.e. the total porosity of gas-bearing tight sandstone reservoirs, refers to the ratio of the sum of the volumes of all pore spaces in the reservoir rock to the total volume of the rock, expressed as a percentage, which can reflect the ability of the formation (reservoir) to store fluids.

[0036] 3. Density porosity is the porosity interpreted using density logging data. Density logging is a logging method that uses gamma rays emitted by a gamma source to irradiate the bottom layer and measures the volume density of the formation based on the Compton effect. The density porosity is calculated using the linear relationship between the electron density in the formation and its true volume density.

[0037] 4. Neutron porosity is the porosity interpreted using neutron logging data. Neutron logging uses the deceleration and capture process of neutrons by rocks. A neutron source is used downhole to emit a continuous stream of fast neutrons to the formation. These fast neutrons produce nuclear collisions with the elements of the formation, causing the neutron energy to be lost and decelerated. Among them, hydrogen can be used as the strongest moderator, but the mineral composition of the sandstone in the reservoir does not contain hydrogen. Therefore, the hydrogen content of the sandstone is basically distributed in the fluid in the pores of the sandstone, that is, water and oil and gas. It can be seen that neutron logging reflects the porosity of the rock filled with fluid, which is essentially equivalent to the hydrogen content index.

[0038] 5. Core analysis is a general term for the technology of observing and analyzing the characteristics of oil and gas layers using various instruments and equipment that can reveal the nature of rocks.

[0039] 6. Core analysis porosity refers to the ratio of the sum of the volumes of all pore spaces in a rock sample to the volume of the rock sample.

[0040] Embodiment 1

[0041] Usually, the study of tight sandstone reservoirs uses methods such as sonic logging, density logging, and compensated neutron logging. For the sonic logging method, since the tight sandstone reservoir has secondary pores in addition to the matrix pores, but the sonic logging can only reflect the matrix pores, the sonic porosity obtained by sonic logging is generally smaller than the total porosity of the tight sandstone reservoir and the porosity of the core analysis. For the density logging method, the volume density curve is generally smaller due to the influence of drilling fluid and reservoir gas content. The porosity obtained by simply calculating the volume density is generally greater than the true porosity of the formation, and is also generally greater than the porosity of the core analysis. For the compensated neutron logging method, its detection depth depends on the hydrogen content of the formation. However, when there is natural gas in the pore space of the formation around the wellbore wall, the detection depth of the compensated neutron logging will increase. Affected by the gas-bearing characteristics, the logging value will be much lower than the porosity when the formation contains oil or water. The higher the gas saturation of the formation, the smaller the porosity obtained by the neutron logging method will be. Therefore, in porosity logging, since the vertical depth of the compensated neutron logging is greater than the lithology density, the logging information collected by the neutron logging and density logging methods is also affected differently by the formation natural gas, that is, the influence of natural gas on the porosity calculated based on density logging and neutron logging is not equal, and due to the different formation gas saturations, the degree of influence on the compensated neutron logging is also different.

[0042] In view of this, an embodiment of the present invention provides a method for determining the porosity of a gas-bearing tight sandstone reservoir, such as Figure 1 As shown, the determination method includes steps S110 to S120:

[0043] Step S110, based on model parameters related to the porosity of the gas-bearing tight sandstone reservoir, establish a first calculation model for the porosity of the gas-bearing tight sandstone reservoir, wherein the model parameters include density porosity, neutron porosity and associated weight coefficients, and the weight coefficients are used to characterize the degree of influence of the natural gas contained in the gas-bearing tight sandstone reservoir on the density porosity and the neutron porosity.

[0044] For example, the present invention takes into account the impact of gas content in tight sandstone reservoirs on porosity, introduces weight coefficients for the influence of density porosity and neutron porosity logging, and establishes a model for gas-bearing tight sandstone reservoirs based on the combination of density porosity and neutron porosity and the weight coefficients, so that the porosity of gas-bearing tight sandstone reservoirs can be determined based on the established calculation model.

[0045] Step S120: obtaining the porosity of the gas-bearing tight sandstone reservoir based on the established first calculation model.

[0046] For example, after a calculation model is established for a tight sandstone reservoir, the embodiment of the present invention needs to determine various model parameters in the calculation model, and then calculate the porosity of the gas-bearing tight sandstone reservoir.

[0047] In a preferred embodiment, the first calculation model for the porosity of the gas-bearing tight sandstone reservoir is characterized by the following formula:

[0048] φ=φN×p n +φD×(1-p n ) (1)

[0049] Wherein, φ is the porosity of the gas-bearing tight sandstone reservoir, p n is the weight coefficient, φ D is the density porosity of the gas-bearing tight sandstone reservoir, φ N is the neutron porosity of the gas-bearing tight sandstone reservoir.

[0050] For example, it can be seen from formula (1) that in the porosity calculation model of the embodiment of the present invention, P n can be regarded as a characterization of the neutron porosity φ N The degree of influence, and (1-P n ) is considered to represent the density porosity φ D degree of impact.

[0051] Preferably, for the above formula (1), the density porosity φ D It is determined using the following formula:

[0052]

[0053] Wherein, ρ is the density logging value of the gas-bearing tight sandstone reservoir, ρ ma is the rock skeleton value of the gas-bearing tight sandstone reservoir, ρ f is the formation fluid density of the gas-bearing tight sandstone reservoir, V sh is the shale content of the gas-bearing tight sandstone reservoir, ρ sh is the mudstone density value of the gas-bearing tight sandstone reservoir.

[0054] For example, it can be seen from the above formula (2) that the embodiment of the present invention obtains the parameter value of density porosity based on the correlation between the density logging value, rock skeleton value, formation fluid density value, mud content and mudstone density value of the gas-bearing tight sandstone reservoir.

[0055] It should be noted that the determination of the density porosity parameter value in the embodiment of the present invention is not limited to the above formula (2). Those skilled in the art can apply calculation formulas based on different correlations and factors to obtain the density porosity parameter value according to actual needs.

[0056] In a preferred embodiment, for the above formula (1), the neutron porosity φ N It is determined using the following formula:

[0057] φ N =CNL-φ Nma -V sh φ sh (3)

[0058] Wherein, CNL is the neutron logging value of the gas-bearing tight sandstone reservoir, φ Nma is the neutron skeleton value of the gas-bearing tight sandstone reservoir, φ sh is the mudstone neutron value of the gas-bearing tight sandstone reservoir.

[0059] For example, it can be seen from the above formula (3) that the embodiment of the present invention obtains the parameter value of neutron porosity based on the correlation between the neutron logging value, neutron skeleton value and mudstone neutron value of the gas-bearing tight sandstone reservoir.

[0060] It should be noted that the determination of the parameter value of neutron porosity in the embodiment of the present invention is not limited to the above formula (3). Those skilled in the art can apply calculation formulas based on different correlation relationships and factors to obtain the parameter value of density porosity according to actual needs.

[0061] In a preferred embodiment, if Figure 2 As shown, the associated weight coefficients are determined based on the following steps:

[0062] Step S210: establishing a second calculation model for the weight coefficient based on the core analysis porosity of the gas-bearing tight sandstone reservoir, wherein the second calculation model is configured to characterize the relationship between the weight coefficient and the core analysis porosity.

[0063] Step S220: determining the weight coefficient based on the second calculation model.

[0064] For example, the relationship between the weight coefficient and the porosity of core analysis can be expressed by the following function:

[0065] p n =f(φ 岩心 ) (4)

[0066] Among them, φ 岩心 The cores were analyzed for porosity (%).

[0067] In a preferred embodiment, Figure 3 As shown, the establishing of the second calculation model for the weight coefficient includes:

[0068] Step S310: assign values ​​to the weight coefficients in the first calculation model in sequence based on the value interval and value gradient of the weight coefficients to obtain the corresponding first porosity of the gas-bearing tight sandstone reservoir.

[0069] Step S320, comparing the obtained first porosity of the gas-bearing tight sandstone reservoir with the core analysis porosity, and when the two are consistent, determining the value of the weight coefficient corresponding to the first porosity as the value of the weight coefficient corresponding to the core analysis porosity.

[0070] Step S330, fitting all core analysis porosities and their corresponding weight coefficients to obtain a fitting curve that characterizes the relationship between the corresponding weight coefficient and the core analysis porosity, so as to establish a calculation model for the weight coefficient based on the fitting curve.

[0071] For example, assuming that the value range of the weight coefficient is 0 to 1, and the value gradient is 0.01, based on the porosity calculation model introduced above, the weight coefficient in the calculation model is assigned, and the first porosity corresponding to the assignment is calculated. Since the embodiment of the present invention assigns values ​​in sequence based on the assignment gradient, multiple corresponding first porosities can be obtained. It should be noted that the first porosity of the gas-bearing tight sandstone reservoir here is not the total porosity mentioned above, but the corresponding simulated calculation value obtained according to the assignment of different weight coefficients. Further, the first porosity is compared with the core analysis porosity. When the first porosity is consistent with the core analysis porosity, the value of the weight coefficient corresponding to the first porosity is determined to be the value of the weight coefficient corresponding to the core analysis porosity, wherein the consistency referred to here means that the first porosity is closest to the core analysis porosity, or the first porosity is equal to the core analysis porosity.

[0072] Since the core analysis porosity obtained varies with the depth of the reservoir, different core analysis porosity data are obtained for different depths of the tight sandstone reservoir. The embodiment of the present invention can obtain the assignment of multiple weight coefficients corresponding to all core analysis porosities through the above method, and then fit the assignment of multiple weight coefficients with multiple core analysis porosities to obtain the relationship between the weight coefficient and the core analysis porosity, thereby establishing a calculation model for the weight coefficient.

[0073] In a more preferred embodiment, the determination method also includes determining the core analysis porosity of the gas-bearing tight sandstone reservoir, which includes: obtaining the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir based on the neutron porosity and density porosity of the gas-bearing tight sandstone reservoir, and using the neutron-density intersection porosity as the core analysis porosity.

[0074] For example, core analysis porosity needs to be based on core sampling and analyzed through core data. In practical applications, considering the limited data and the complexity and difficulty of core sampling, it is impossible to effectively obtain multiple sets of core analysis porosity data. The core analysis porosity is characterized by a single porosity, that is, neutron porosity or density porosity is used to characterize the core analysis porosity. Since both have a large deviation from the actual core analysis porosity, the accuracy of the weight coefficient calculated by using a single porosity to characterize the core analysis porosity is not high. Therefore, the embodiment of the present invention takes into account that the neutron-density intersection porosity can eliminate the influence of part of the gas content in the tight sandstone reservoir, which is closer to the porosity of the reservoir, that is, the core analysis porosity, than the single density porosity or neutron porosity. Therefore, in the weight coefficient calculation process, the embodiment of the present invention uses the neutron-density intersection porosity to replace the core analysis porosity.

[0075] Preferably, the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir is obtained using the following formula:

[0076]

[0077] Among them, φ DN is the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir, φ D is the density porosity of the gas-bearing tight sandstone reservoir, φ N is the neutron porosity of the gas-bearing tight sandstone reservoir.

[0078] In summary, the method for determining the porosity of a gas-bearing tight sandstone reservoir provided by the embodiment of the present invention has the following advantages:

[0079] 1) Introduce weight coefficient calculation to reduce the impact of reservoir gas content on porosity;

[0080] 2) Reduce the calculation error of porosity and improve the accuracy of porosity calculation for tight sandstone reservoirs;

[0081] 3) Provide accurate data support for subsequent reserve calculations and development decisions, and effectively meet the accuracy requirements of subsequent reservoir reserve calculations.

[0082] Embodiment 2

[0083] The embodiment of the present invention is a specific example application of the method for determining the porosity of a gas-bearing tight sandstone reservoir based on the first embodiment, so as to further elaborate on the process of determining the porosity of a gas-bearing tight sandstone reservoir.

[0084] The present invention takes the Pinghu Formation Pingzhong and upper reservoirs in the A gas field in the East China Sea as an example. The reservoir is buried at a depth of 4100-4300m, and its lithology is mainly fine sandstone, with a porosity distribution between 3.5% and 22%. The reservoir is buried at a great depth, and its lithology is dense, which is a tight gas reservoir. The well logging series of the gas field is comprehensive, and all exploration wells have been subjected to neutron logging and density logging, and the core analysis data is rich.

[0085] For example, the drilling fluid density of Well A1 is 1.45g / cm3, and the target layer 4103.3-4123.9m gas logging shows abnormal display, and the well logging shows fine sandstone, 4103-4118m, the maximum total hydrocarbon is 78%, and the reservoir does not contain water. The neutron logging value of this section of the formation is between 2.7 and 10.9%, the density logging value is between 2.24 and 2.63g / cm3, the deep detection resistivity value is between 30.0 and 95.0Ω.m, the array lateral positive amplitude difference is obvious, and the core analysis porosity is 3.4-21.9%.

[0086] First, based on the distribution relationship between the weight coefficient and the porosity of core analysis, a function curve reflecting the change law of the weight coefficient with the porosity of core analysis is established, such as Figure 4As shown, the horizontal axis x is the core analysis porosity, which is expressed as neutron-density intersection porosity in the embodiment of the present invention, and the vertical axis y is the weight coefficient. Figure 4 It can be seen that the weight coefficient and the porosity of core analysis satisfy the following relationship:

[0087] When φ<0.1: p n =0.8

[0088] When 0.1≤φ≤0.15: p n =12.218*φ-1.0118

[0089] When φ>0.15: p n =0.25

[0090] Furthermore, based on the above obtained variation relationship, the corresponding weight coefficient is substituted into the porosity calculation model, and finally the porosity of the gas field reservoir is obtained.

[0091] Figure 5 The following is a schematic diagram of the porosity calculation results obtained using neutron, density, neutron-density intersection and weight coefficient methods. Figure 5 It can be seen that the calculation result of the reservoir porosity obtained by the weight coefficient method of the present application is closest to the porosity of the core analysis. Therefore, the porosity obtained by the weight coefficient method of the embodiment of the present invention is more accurate and has a smaller error than the existing method.

[0092] Figure 6 This is a comparison chart of the porosity calculated by the neutron-density intersection method and the porosity analyzed by core analysis. Figure 6 It can be seen that since the neutron porosity calculated by logging is between 4.6% and 12.6%, and the density porosity is between 1.1% and 23%, the neutron density intersection porosity is between 3.4% and 18.6%, the absolute error is between -3.44% and 2.37%, the relative error is between 0.1% and 27.66%, and the average relative error is 9.4%, which does not meet the requirement of less than 8% for reserve calculation.

[0093] Figure 7 This is a comparison chart of the porosity calculated using the weight coefficient method and the porosity obtained by core analysis. Figure 7 It can be seen that the porosity calculated by the weight coefficient method is distributed between 3.44% and 21.9%, the absolute error is between -2.1% and 1.9%, the relative error is between 0.1% and 18.5%, and the average relative error is 5.7%, which meets the requirement of less than 8% for reserve calculation. Obviously, the porosity calculated by the weight coefficient method can make the subsequent reserve calculation results meet the accuracy requirements and provide accurate data support for subsequent reservoir development.

[0094] Embodiment 3

[0095] Based on the same inventive concept as that of Example 1, an embodiment of the present invention provides a device for determining the porosity of a gas-bearing tight sandstone reservoir, the device comprising: a memory storing a program that can be run on a processor; and the processor configured to implement the method for determining the porosity of a gas-bearing tight sandstone reservoir described in Example 1 above when executing the program.

[0096] Correspondingly, an embodiment of the present invention further provides a machine-readable storage medium, on which instructions are stored, and the instructions are used to enable a machine to execute the method for determining the porosity of a gas-bearing tight sandstone reservoir described in the above-mentioned embodiment 1 of the present application.

[0097] For more implementation details and beneficial effects of the embodiments of the present invention, reference may be made to the above embodiments, which will not be described in detail here.

[0098] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0099] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, 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 generate 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 flowchart and / or block diagram. 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.

[0100] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 A function specified in one or more boxes.

[0101] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0102] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0103] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0104] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0105] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0106] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for determining the porosity of a gas-bearing tight sandstone reservoir, characterized in that: The determination method comprises: Based on model parameters related to the porosity of the gas-bearing tight sandstone reservoir, a first calculation model for the porosity of the gas-bearing tight sandstone reservoir is established, wherein the model parameters include density porosity, neutron porosity and associated weight coefficients, and the weight coefficients are used to characterize the influence of the natural gas contained in the gas-bearing tight sandstone reservoir on the density porosity and the neutron porosity; The porosity of the gas-bearing tight sandstone reservoir is obtained based on the established first calculation model.

2. The determination method according to claim 1, characterized in that: The first calculation model for the porosity of the gas-bearing tight sandstone reservoir is characterized by the following formula: φ=φN×p n +φD×(1-p n ) Wherein, φ is the porosity of the gas-bearing tight sandstone reservoir, p n is the weight coefficient, φ D is the density porosity of the gas-bearing tight sandstone reservoir, φ N is the neutron porosity of the gas-bearing tight sandstone reservoir.

3. The determination method according to claim 2, characterized in that: The density porosity φ D It is determined using the following formula: Wherein, ρ is the density logging value of the gas-bearing tight sandstone reservoir, ρ ma is the rock skeleton value of the gas-bearing tight sandstone reservoir, ρ f is the formation fluid density of the gas-bearing tight sandstone reservoir, V sh is the shale content of the gas-bearing tight sandstone reservoir, ρ sh is the mudstone density value of the gas-bearing tight sandstone reservoir.

4. The determination method according to claim 2, characterized in that: The neutron porosity φ N It is determined using the following formula: f N =CNL-φ Nma -V sh f sh Wherein, CNL is the neutron logging value of the gas-bearing tight sandstone reservoir, φ Nma is the neutron skeleton value of the gas-bearing tight sandstone reservoir, φ sh is the mudstone neutron value of the gas-bearing tight sandstone reservoir.

5. The determination method according to claim 1, characterized in that: The associated weights are determined based on the following steps: Based on the core analysis porosity of the gas-bearing tight sandstone reservoir, establishing a second calculation model for the weight coefficient, wherein the second calculation model is configured to characterize the relationship between the weight coefficient and the core analysis porosity; Based on the second calculation model, the weight coefficient is determined.

6. The determination method according to claim 5, characterized in that: The establishing of a second calculation model for the weight coefficient comprises: Based on the value interval and value gradient of the weight coefficient, the weight coefficients in the first calculation model are assigned values ​​in sequence to obtain the corresponding first porosity of the gas-bearing tight sandstone reservoir; Comparing the first porosity of the gas-bearing tight sandstone reservoir with the core analysis porosity, and when they are consistent, determining that the value of the weight coefficient corresponding to the first porosity is the value of the weight coefficient corresponding to the core analysis porosity; All core analysis porosities are fitted with their corresponding weight coefficient assignments to obtain a fitting curve that characterizes the relationship between the corresponding weight coefficient and the core analysis porosity, so as to establish a calculation model for the weight coefficient based on the fitting curve.

7. The determination method according to claim 5, characterized in that: The determination method further includes determining the core analysis porosity of the gas-bearing tight sandstone reservoir, which includes: Based on the neutron porosity and the density porosity of the gas-bearing tight sandstone reservoir, the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir is obtained, and the neutron-density intersection porosity is used as the core analysis porosity.

8. The determination method according to claim 7, characterized in that: The neutron-density intersection porosity of the gas-bearing tight sandstone reservoir is obtained by the following formula: Among them, φ DN is the neutron-density intersection porosity of the gas-bearing tight sandstone reservoir, φ D is the density porosity of the gas-bearing tight sandstone reservoir, φ N is the neutron porosity of the gas-bearing tight sandstone reservoir.

9. A device for determining the porosity of a gas-bearing tight sandstone reservoir, characterized in that: The determining device comprises: a memory storing a program that can be executed on the processor; and The processor is configured to implement the method for determining the porosity of a gas-bearing tight sandstone reservoir as described in any one of claims 1 to 8 when executing the program.

10. A machine-readable storage medium having instructions stored thereon, the instructions being used to enable a machine to execute the method for determining the porosity of a gas-bearing tight sandstone reservoir as described in any one of claims 1 to 8 of the present application.

Images