Permeability determination method and system

Abstract

The invention provides a permeability determination method and system, and belongs to the technical field of well logging. The determination method comprises the following steps: determining a rock skeleton density corresponding to each lithology according to a plurality of porosities and a plurality of rock densities corresponding to each lithology in a plurality of lithologies of a rock sample; constructing a permeability model corresponding to each lithology according to the plurality of porosities and the plurality of permeability corresponding to each lithology of the rock sample; determining the rock skeleton density and porosity of the to-be-measured rock along with the change of depth according to the rock components of the to-be-measured rock; and determining the change of the permeability corresponding to the lithology of the rock to be measured along with the depth according to the rock skeleton density and permeability model corresponding to each lithology and the rock skeleton density and porosity of the rock to be measured along with the change of the depth. According to the method, under the complex lithologic condition, various lithologic characters of the rock can be effectively identified, so that the permeability corresponding to each lithologic character in the various lithologic characters is determined, and the calculation precision of the permeability is improved.

Description

Technical Field

[0001] The present invention relates to the field of well logging technology, and in particular to a method and system for determining permeability. Background Art

[0002] Permeability is an extremely important parameter in the evaluation of oil and gas reservoirs. The most widely used method in the industry is to calculate permeability using well logging methods. Usually, in the case of a single lithology, permeability is calculated by establishing a relationship model between porosity and permeability. However, in the case of complex lithology, the permeability calculated by the above method has low accuracy, mainly because different lithologies have different permeability models. At present, many methods cannot effectively identify different lithologies, so that it is impossible to calculate permeability by lithology, resulting in reduced accuracy of permeability calculation and failure to meet the requirements of detailed evaluation of oil and gas fields. Summary of the invention

[0003] The purpose of the embodiment of the present invention is to provide a method and system for determining permeability, which uses rock samples to determine the rock skeleton density corresponding to each lithology and the permeability model corresponding to each lithology, and determines multiple lithologies of the rock to be tested based on the rock skeleton density that changes with depth of the rock to be tested, thereby determining the permeability models corresponding to the multiple lithologies, and finally determining the permeability of each of the multiple lithologies in the rock to be tested. Under complex lithology conditions, the present invention can effectively identify multiple lithologies of rocks, thereby determining the permeability corresponding to each of the multiple lithologies, thereby improving the accuracy of permeability calculation.

[0004] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides a method and system for determining permeability, the determination method comprising: determining a rock skeleton density corresponding to each lithology of the rock sample according to multiple porosities and multiple rock densities corresponding to each lithology of multiple lithologies of the rock sample; constructing a permeability model corresponding to each lithology of the rock sample according to the multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample; determining the rock skeleton density of the rock to be tested that varies with depth and the porosity of the rock to be tested that varies with depth according to the rock components to be tested; and determining the permeability corresponding to the lithology of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that varies with depth, and the porosity of the rock to be tested that varies with depth.

[0005] Optionally, determining the rock skeleton density corresponding to each lithology of the rock sample according to the multiple porosities and the multiple rock densities corresponding to each lithology of the multiple lithologies of the rock sample comprises: constructing the rock skeleton density b corresponding to the lithology i according to the multiple porosities and the multiple rock densities corresponding to the lithology i of the rock sample. i :DEN=a i POR+b i , where DENi is a plurality of rock densities corresponding to the lithology i of the rock sample, PORi is a plurality of porosities corresponding to the lithology i of the rock sample, and a i and b i are the linear fitting coefficients corresponding to the rock i of the rock sample.

[0006] Optionally, constructing the permeability model corresponding to each lithology of the rock sample according to the multiple porosities and the multiple permeabilities corresponding to each lithology of the rock sample comprises: constructing the permeability model corresponding to lithology i of the rock sample according to the multiple porosities and the multiple permeabilities corresponding to lithology i of the rock sample, Where PERM is the permeability corresponding to the lithology i of the rock sample, c i and i are all fitting coefficients corresponding to the lithology i of the rock sample.

[0007] Optionally, determining the rock skeleton density of the rock to be tested and the porosity of the rock to be tested that changes with depth based on the rock components to be tested includes: constructing a group of equations for the rock components to be tested based on the rock components to be tested; determining the rock skeleton density of the rock to be tested that changes with depth based on the group of equations for the rock components to be tested; and determining the porosity of the rock to be tested that changes with depth based on the rock skeleton density of the rock to be tested that changes with depth.

[0008] Optionally, the rock components include: silica, calcium and argillaceous. Accordingly, constructing the rock component equation group according to the rock components includes:

[0009] V 硅质 (d) ×DEN 硅质 +V 钙质 (d) ×DEN 钙质 +V 泥质 (d) ×DEN 泥质 +POR es (d) ×DEN 泥体 =DEN(d),

[0010] V 硅质 (d) ×AC 硅质 +V钙质 (d) ×AC 钙质 +V 泥质 (d) ×AC 泥质 +POR es (d) ×AC 流体 =AC(d),

[0011] V 硅质 (d) ×CNL 硅质 +V 钙质 (d) ×CNL 钙质 +V 泥质 (d) ×CNL 泥质 +POR es (d) ×CNL 流体 =CNL(d),

[0012] V 硅质 (d)+V 钙质 (d)+V 泥质 (d)+POR es (d) = 1,

[0013] Among them, V 硅质 (d) V 钙质 (d) V 泥质 (d) is the volume percentage of siliceous, calcareous and argillaceous materials with depth; DEN 硅质 、DEN 钙质 、DEN 泥质 、DEN 流体 are the density characteristic values ​​of siliceous, calcareous, muddy and fluid respectively; AC 硅质 , AC 钙质 , AC 泥质 , AC 流体 are the acoustic time difference characteristic values ​​of siliceous, calcareous, muddy and fluid respectively; CNL 硅质 、CNL 钙质 、CNL 泥质 、CNL 流体 are the compensated neutron characteristic values ​​of siliceous, calcareous, argillaceous and fluid respectively; DEN(d) is the compensated density logging value of the rock to be tested that varies with depth; AC(d) is the compensated acoustic time difference logging value of the rock to be tested that varies with depth; CNL(d) is the compensated neutron logging value of the rock to be tested that varies with depth; POR es (d) is the estimated porosity of the rock to be tested that varies with depth.

[0014] Optionally, determining the rock skeleton density of the rock to be tested that varies with depth according to the rock component equation group of the rock to be tested comprises: determining the volume percentage V of the siliceous material of the rock to be tested that varies with depth according to the rock component equation group of the rock to be tested.硅质 (d) The volume percentage V of the calcium content of the rock to be tested as it changes with depth 钙质 (d); According to the volume percentage V of the silica of the rock to be tested that varies with depth 硅质 (d) The volume percentage V of the calcium content of the rock to be tested as it changes with depth 钙质 (d) and the following formula to determine the rock skeleton density DEN of the rock to be tested as it changes with depth: 骨架 (d):

[0015] DEN 骨架 (d) = V 硅质 (d) ×DEN 硅质 +V 钙质 (d) ×DEN 钙质 +V 泥质 (d) ×DEN 泥质 .

[0016] Optionally, according to the rock skeleton density DEN of the rock to be measured that varies with depth 骨架 (d) and the following formula, determining the porosity POR(d) of the rock to be tested as it changes with depth includes:

[0017]

[0018] Optionally, determining the permeability of the rock to be tested based on the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, and the porosity of the rock to be tested that varies with depth includes: determining the lithology of the rock to be tested based on the rock skeleton density corresponding to each lithology of the rock sample and the rock skeleton density of the rock to be tested that varies with depth; determining the permeability model corresponding to the lithology of the rock to be tested from the permeability model corresponding to each lithology of the rock sample; and determining the permeability corresponding to the lithology of the rock to be tested based on the porosity of the rock to be tested that varies with depth and the permeability model corresponding to the lithology of the rock to be tested.

[0019] Optionally, the determining the lithology of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample and the rock skeleton density of the rock to be tested that varies with depth comprises: when the rock skeleton density of the rock to be tested that varies with depth is greater than the rock skeleton density b i To b i+1 When , the type of lithology is determined to be lithology i.

[0020] On the other hand, the present invention also provides a permeability determination system, which includes: a first acquisition module, used to determine the rock skeleton density corresponding to each lithology of the rock sample based on multiple porosities and multiple rock densities corresponding to each lithology of the multiple lithologies of the rock sample; a second acquisition module, used to construct a permeability model corresponding to each lithology of the rock sample based on the multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample; a first determination module, used to determine the rock skeleton density of the rock to be tested that varies with depth and the porosity of the rock to be tested that varies with depth based on the rock components to be tested; and a second determination module, used to determine the permeability corresponding to the lithology of the rock to be tested based on the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that varies with depth, and the porosity of the rock to be tested that varies with depth.

[0021] Through the above technical scheme, according to the multiple porosities and multiple rock densities corresponding to each lithology of the multiple lithologies of the rock sample, the rock skeleton density corresponding to each lithology of the rock sample is determined. This step provides an important basis for the subsequent determination of the lithology of the rock to be tested; according to the multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample, a permeability model corresponding to each lithology of the rock sample is constructed. The main purpose of this step is to determine the permeability model corresponding to the lithology of the rock to be tested after the lithology of the rock to be tested is determined; according to the rock component equation group of the rock to be tested, the permeability model corresponding to the lithology of the rock to be tested is determined. The porosity that changes with depth; and according to the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density that changes with depth of the rock to be tested, and the porosity that changes with depth of the rock to be tested, the permeability corresponding to the lithology of the rock to be tested is determined. That is, when the lithology of the rock to be tested is determined in the above steps, the permeability model corresponding to the lithology can be determined accordingly, and finally the known porosity that changes with depth of the rock to be tested is substituted into the corresponding permeability model, and the permeability corresponding to the lithology of the rock to be tested can be determined. Therefore, the present invention can effectively identify multiple lithologies of rocks under complex lithology conditions, thereby determining the permeability corresponding to each of the multiple lithologies, thereby improving the calculation accuracy of the permeability.

[0022] 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

[0023] 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:

[0024] Figure 1 is a flow chart of a method for determining permeability provided by an embodiment of the present invention;

[0025] Figure 2A , 2B 2C is a relationship diagram between porosity and rock density corresponding to three different lithologies of rock samples provided in an embodiment of the present invention;

[0026] Figure 3 are the permeability models corresponding to the three lithologies of the rock samples fitted according to the embodiment of the present invention;

[0027] Figure 4 It is a comparison diagram of the effects provided by the embodiments of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] Figure 1 It is a flow chart of a method for determining permeability provided by an embodiment of the present invention. The determination method comprises: S101, determining the rock skeleton density corresponding to each lithology of the rock sample according to multiple porosities and multiple rock densities corresponding to each lithology of the rock sample; S102, constructing a permeability model corresponding to each lithology of the rock sample according to multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample; S103, determining the rock skeleton density of the rock to be tested that varies with depth and the porosity of the rock to be tested that varies with depth according to the rock components to be tested; S104, determining the permeability corresponding to the lithology of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that varies with depth, and the porosity of the rock to be tested that varies with depth.

[0030] Before the step S101, the method for determining the permeability further includes the following step S201.

[0031] S201. Performing physical property experiments on rock samples to obtain a plurality of porosities and a plurality of rock densities corresponding to each of a plurality of lithologies of the rock samples.

[0032] Specifically, the rock sample may be a core, and the number of selected cores may be multiple, so as to obtain multiple lithologies of the rock sample and multiple porosities and multiple rock densities corresponding to each lithology. It should be noted that the physical property experiment refers to the physical property experiment of the core according to the process specified in the standard "Core Analysis Method SY / T5336-2006", and the core physical property experiment includes a core porosity experiment and a core permeability experiment. Using the physical property experiment, multiple porosities and rock densities corresponding to each lithology of the lithology sample are obtained. The multiple lithologies may include common fine sandstone, medium sandstone, and conglomerate, but in practical applications, they are not limited to the above three lithologies, and may also include siltstone, gravel sandstone, etc. Among them, since multiple sample points are taken on the rock sample, each lithology of the rock sample correspondingly includes multiple porosities and multiple rock densities. For example, the rock sample with the rock type of fine sandstone corresponds to multiple porosity values ​​and multiple rock densities, and the rock sample with the lithology of medium sandstone also corresponds to multiple porosities and rock densities. In addition, each rock sample can contain one lithology or multiple lithologies at the same time.

[0033] Steps S101-S104 are executed on the basis of a plurality of porosities and a plurality of rock densities corresponding to each of the plurality of lithologies of the rock samples that have been obtained.

[0034] The specific details of steps S101 - S104 are described below.

[0035] S101. Determine the rock skeleton density corresponding to each lithology of the rock sample according to multiple porosities and multiple rock densities corresponding to each lithology of the rock sample.

[0036] Further, constructing the rock skeleton density corresponding to each lithology of the rock sample according to the multiple porosities and the multiple rock densities corresponding to each lithology of the multiple lithologies of the rock sample includes: constructing the rock skeleton density b corresponding to the lithology i according to the multiple porosities and the multiple rock densities corresponding to the lithology i of the rock sample i :DENi=a i PORi+b i ,

[0037] Wherein, DENi is a plurality of rock densities corresponding to the lithology i of the rock sample, PORi is a plurality of porosities corresponding to the lithology i of the rock sample, and a i and b i are the linear fitting coefficients corresponding to the lithology i of the rock sample.

[0038] Specifically, it is assumed that the obtained rock sample has multiple lithologies, which can be represented by i. And the rock sample needs to cover multiple lithologies of the rock to be tested. It can be understood that the lithology of the rock sample almost covers all the lithologies of the rock to be tested. The more lithologies the rock sample contains, the more complex the lithology of the rock sample is. For the multiple porosities and multiple rock densities corresponding to the lithology i of the rock sample, the rock skeleton density b corresponding to the lithology i is constructed. i :DENi=a i PORi+b i For example, there are N types of lithology. Each lithology contains multiple porosities and multiple rock densities. The multiple porosities and multiple rock densities of each lithology are classified and counted, and linear formula fitting is performed on the classified multiple porosities PORi and multiple rock densities DENi. The fitted formulas for each lithology are DEN1=a1POR1+b1, DEN2=a2POR2+b2, ..., DENi=a i PORi+b i ,…,DENN=a N PORN+b N When multiple porosities PORi and multiple rock densities DENi are known, the corresponding rock skeleton density b of each lithology can be fitted respectively. i . For the convenience of explanation, the various lithologies in the embodiments provided by the present invention are all described by taking fine sandstone, medium sandstone and conglomerate as examples, with lithology 1 representing fine sandstone, lithology 2 representing conglomerate and lithology 3 representing medium sandstone (the order of lithology numbers can be set as needed). The relationship between the porosity and rock density corresponding to lithology 1 being fine sandstone can be expressed as DEN1=a1POR1+b1; the relationship between the porosity and rock density corresponding to lithology 2 being conglomerate can be expressed as DEN2=a2POR2+b2; the relationship between the porosity and rock density corresponding to lithology 3 being medium sandstone can be expressed as DEN3=a3POR3+b3. For details, please refer to Figure 2A , 2B , 2C are the relationship diagrams between porosity and rock density corresponding to three different lithologies.

[0039] After fitting the rock skeleton density b of each lithology i Afterwards, it can be used as a lithology identification standard for determining the rock to be tested. For details, please refer to the description in step S104.

[0040] S102: construct a permeability model corresponding to each lithology of the rock sample according to the multiple porosities and multiple permeabilities corresponding to each lithology.

[0041] Further, according to a plurality of porosities and a plurality of permeabilities corresponding to the lithology i of the rock sample, a permeability model corresponding to the lithology i of the rock sample is constructed, Where PERMi is the permeability corresponding to the lithology i of the rock sample, c i and i are all fitting coefficients corresponding to the lithology i of the rock sample.

[0042] According to the multiple porosities PORi and multiple permeabilities PERMi corresponding to the lithology i of the lithology sample obtained in step S201, a permeability model corresponding to the lithology i of the rock sample is constructed as follows: Still taking fine sandstone, medium sandstone and conglomerate as an example, lithology 1 represents fine sandstone, lithology 2 represents gravel or conglomerate, and lithology 3 represents medium sandstone. Then lithology 1 is fine sandstone, and the corresponding permeability model can be expressed as: Lithology 2 is sandy conglomerate, and the corresponding permeability model can be expressed as: Lithology 3 is medium sandstone, and the corresponding permeability model can be expressed as: It should be noted that there is a one-to-one correspondence between the lithology i corresponding to the rock skeleton density and the lithology i corresponding to the permeability model. Using multiple porosities PORi and multiple permeabilities PERMi corresponding to the rock samples, c can be calculated accordingly. i and d i For example, the corresponding permeability model for lithology 1 being fine sandstone is: PERM1 = 0.0002e POR1*0.8333 ; The permeability model corresponding to lithology 2, gravel or conglomerate, is: PERM2 = 0.1749e POR2*0.4674 ; The permeability model corresponding to lithology 3, medium sandstone, is: PERM3 = 7E-0.5e POR3 *1.0308 For details, please refer to Figure 3 , Figure 3 These are the permeability models corresponding to the three lithologies of the fitted rock samples.

[0043] The above steps S101-S102 are to construct a permeability model corresponding to each lithology of the rock sample according to the multiple porosities PORi and multiple permeabilities PERMi corresponding to each lithology of the known rock sample, and finally the determined permeability model can be combined with the rock skeleton density b corresponding to each lithology of the rock sample. i , predict the permeability corresponding to the lithology of the rock to be tested in practical applications, and refer to the description in step S104 for details.

[0044] S103. Determine the rock skeleton density of the rock to be tested and the porosity of the rock to be tested that varies with depth according to the rock components to be tested.

[0045] The rock to be measured may be the rock that actually needs logging measurement. Figure 4 For example, when studying the geology at a depth of 4110 to 4170 meters underground, a group of rock skeleton density and porosity of the rock to be tested can be determined at a certain depth interval (for example, 0.1 meter), and 600 groups of rock skeleton density and porosity can be determined accordingly based on the change of the rock to be tested with depth. It should be noted that the rock skeleton density of the rock to be tested that changes with depth and the porosity of the rock to be tested that changes with depth mean that a group of rock skeleton density and porosity of the rock to be tested is determined at a certain depth interval (for example, 0.1 meter) along the depth of the rock to be tested underground.

[0046] Furthermore, the step S103 also includes steps S301 - S303 .

[0047] S301. Construct a rock component equation group of the rock to be tested according to the rock component of the rock to be tested.

[0048] Furthermore, the rock components may include: silica, calcium and argillaceous (the rock components include but are not limited to these three components, which may vary according to actual needs). Accordingly, the rock component equation group is constructed according to the rock components (the parameters in the equation group may vary according to the type of actual rock components, or the parameters may increase or decrease accordingly according to the increase or decrease of the type of rock components) including:

[0049] V 硅质 (d) ×DEN 硅质 +V 钙质 (d) ×DEN 钙质 +V 泥质 (d) ×DEN 泥质 +POR es (d) ×DEN 流体 =DEN(d),

[0050] V 硅质 (d) ×AC 硅质 +V 钙质 (d) ×AC 钙质 +V 泥质 (d) ×AC 泥质 +POR es (d) ×AC 流体 =AC(d),

[0051] V 硅质 (d) ×CNL硅质 +V 钙质 (d) ×CNL 钙质 +V 泥质 (d) ×CNL 泥质 +POR es (d) ×CNL 流体 =CNL(d),

[0052] V 硅质 (d)+V 钙质 (d)+V 泥质 (d)+POR es (d) = 1,

[0053] Among them, V 硅质 (d) V 钙质 (d) V 泥质 (d) is the volume percentage of siliceous, calcareous and argillaceous materials with depth, in %, where V 泥质 (d) can be calculated using the natural gamma curve by conventional methods; DEN 硅质 、DEN 钙质 、DEN 泥质 、DEN 流体 are the density characteristic values ​​of siliceous, calcareous, muddy and fluid respectively, which are constants with the unit of g / cm3; AC 硅质 , AC 钙质 , AC 泥质 , AC 流体 The acoustic time difference characteristic values ​​of siliceous, calcareous, muddy and fluid are constants in us / ft; CNL 硅质 、CNL 钙质 、CNL 泥质 、CNL 流体 are respectively the compensated neutron characteristic values ​​of siliceous, calcareous, argillaceous and fluid, which are constants in %; DEN(d) is the compensated density logging value of the rock to be tested that varies with depth; AC(d) is the compensated acoustic time difference logging value of the rock to be tested that varies with depth, and the above parameters can be directly read from the logging curve obtained by the existing technical means; CNL(d) is the compensated neutron logging value of the rock to be tested that varies with depth; POR es (d) is the estimated porosity of the rock to be tested as it changes with depth. es (d) It can be obtained by using existing technical means, for example, by calculating the neutron density curve of conventional well logging methods. 硅质 、DEN 钙质 、CNL 硅质 、CNL 钙质 , AC 硅质 , AC 钙质is a constant, and the value is taken according to the experiment, see Table 1:

[0054] Neutron skeleton (%) <![CDATA[Density skeleton (g / cm 3 )]]> Sonic skeleton (us / ft) <![CDATA[CNL 硅质 =-2]]> <![CDATA[DEN 硅质 =2.65]]> <![CDATA[AC 硅质 =55.5]]> <![CDATA[CNL 钙质 =-1]]> <![CDATA[DEN 钙质 =2.71]]> <![CDATA[AC 钙质 =47.5]]> <![CDATA[CNL 泥质 =28]]> <![CDATA[DEN 泥质 =2.6]]> <![CDATA[AC 泥质 =85]]> <![CDATA[CNL 流体 =100]]> <![CDATA[DEN 流体 =1.0]]> <![CDATA[AC 流体 =189]]>

[0055] Table 1 Skeleton parameters and fluid parameters

[0056] Specifically, taking a certain oil field as an example, the rock components may include: silica, calcium and mud. Of course, the components in the actual geological reservoir may also include iron, and the embodiment of the present invention is described by taking common silica, calcium and mud as examples. Among them, the content of the rock components affects the rock skeleton density and thus affects the lithology of the rock, that is, the volume percentage of each component in the rock components is different, and the rock skeleton density of the corresponding rock to be tested is also different.

[0057] S302: Determine the rock skeleton density of the rock to be tested that varies with depth based on the rock component equation group of the rock to be tested.

[0058] Further, according to the rock component equation group of the rock to be tested, the volume percentage V of the siliceous material of the rock to be tested that varies with depth is determined. 硅质 (d) The volume percentage V of the calcium content of the rock to be tested as it changes with depth 钙质 (d); According to the volume percentage V of the silica of the rock to be tested that varies with depth 硅质 (d) The volume percentage V of the calcium content of the rock to be tested as it changes with depth 钙质 (d) and the following formula to determine the rock skeleton density DEN of the rock to be tested as it changes with depth: 骨架 (d):DEN 骨架 (d) = V 硅质 (d) ×DEN 硅质 +V 钙质 (d) ×DEN 钙质 +V 泥质 (d) ×DEN 泥质 .

[0059] Specifically, according to the rock component equations to be measured in step S301, V 硅质 (d) and V 钙质 (d) and then combined with the existing porosity model to further calculate the rock skeleton density that varies with depth. Figure 4 For example, to study the geology at a depth of 4110 to 4170 meters underground, the V of a group of rocks to be tested can be determined at a certain depth interval (for example, 0.1 meters, which can be set according to actual needs). 硅质 (d) and V 钙质 (d), correspondingly, 600 sets of rock skeleton density DEN can be solved 骨架 (d).

[0060] S303, according to the rock skeleton density DEN of the rock to be tested that changes with depth 骨架 (d) Determine the porosity of the rock to be tested as it changes with depth.

[0061] Further, according to the rock skeleton density DEN of the rock to be measured that varies with depth 骨架 (d) and the following formula, determining the porosity POR(d) of the rock to be tested as it changes with depth includes:

[0062] The porosity POR(d) calculated in this step is more accurate than the estimated value POR obtained by prior art means in step S302. es (d) has higher accuracy.

[0063] For example, when 600 sets of rock skeleton density DEN are obtained, 骨架 Based on the premise of (d), 600 groups of porosity POR(d) can be determined accordingly.

[0064] S104. Determine the permeability corresponding to the lithology of the rock to be tested based on the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that changes with depth, and the porosity of the rock to be tested that changes with depth.

[0065] Furthermore, the step S104 specifically also includes steps S401-S403.

[0066] S401. Determine the lithology of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample and the rock skeleton density of the rock to be tested that varies with depth.

[0067] Further, determining the lithology of the rock to be measured includes: when the rock skeleton density of the rock to be measured that varies with depth is within the rock skeleton density b i To b i+1 When , the type of lithology is determined to be lithology i.

[0068] For example, assuming that the functional relationship between the porosity POR1 and the rock density DEN1 of the rock sample lithology 1 constructed as fine sandstone is: DEN1 = -0.0277POR1 + 2.6747, that is, the rock skeleton density b1 of the constructed fine sandstone is 2.6747 g / cm 3The functional relationship between the porosity POR2 and the rock density DEN2 of lithology 2, which is sandy conglomerate, is: DEN2 = -0.0274POR2 + 2.6482, that is, the rock skeleton density b2 of the constructed sandy conglomerate is 2.6482; the functional relationship between the porosity POR3 and the rock density DEN3 of lithology 3, which is medium sandstone, is: DEN3 = -0.0207POR3 + 2.5794, that is, the rock skeleton density b3 of the constructed medium sandstone is 2.5794. Among them, the determined rock samples b1, b2, and b3 are the rock skeleton densities corresponding to the three different lithologies.

[0069] For example, the rock skeleton density DEN of the rock to be measured varies with depth. 骨架 (d) When there are 600 groups of rock skeleton density, determine the rock skeleton density DEN of each group separately. 骨架 (d) The relationship between the rock skeleton density b1, b2, and b3 of the rock sample to determine the lithology i of the rock to be tested. For example, when the rock skeleton density of the rock to be tested satisfies 2.6482≤DEN 骨架 (d)<2.6747, the lithology of the rock to be tested is determined to be lithology 1, i.e., fine sandstone; when the rock density of the rock to be tested satisfies 2.5794≤DEN 骨架 (d)<2.6482, the lithology of the rock to be tested is determined to be lithology 2, i.e., conglomerate; when the rock skeleton density of the rock to be tested meets DEN 骨架 (d) < 2.5794, the lithology of the rock to be tested is determined to be lithology 3, that is, medium sandstone. Of course, the embodiment of the present invention is not limited to the above-mentioned method for determining the lithology of the rock to be tested, and can also be set according to actual needs, but all of them are based on the rock skeleton density b of the rock sample. i Make settings.

[0070] S402, determining a permeability model corresponding to the lithology of the rock to be tested from the permeability models corresponding to each lithology of the rock sample;

[0071] For example, after the lithology of the rock to be tested is determined according to the above step S401, the permeability model corresponding to the lithology of the rock to be tested can be determined accordingly. For example, when it is determined that the lithology of the rock to be tested has two types (lithology 1 is fine sandstone and lithology 3 is medium sandstone) (in actual situations, there may be only one, two, three or even more types), the corresponding permeability model for determining that lithology 1 is fine sandstone is: PERM1 = 0.0002e POR1*0.8333 The permeability model corresponding to lithology 3, medium sandstone, is: PERM3 = 7E-0.5e POR3*1.0308 , details can be found in Table 2.

[0072] Conditions for determining lithology Lithology-dependent permeability model <![CDATA[2.6482<DEN 骨架 (d)<2.6747, defined as fine sandstone]]> <![CDATA[PERM1=0.0002e POR1*0.8333 ]]> <![CDATA[2.5794<DEN 骨架 (d)<2.6482, defined as conglomerate]]> <![CDATA[PERM2=0.1749e POR2*0.4674 ]]> <![CDATA[DEN 骨架 (d)<2.5794, defined as medium sandstone]]> <![CDATA[PERM3=7E-0.5e POR3*1.0308 ]]>

[0073] Table 2 Correspondence between lithology and permeability model

[0074] S403: Determine the permeability corresponding to the lithology of the rock to be tested according to the porosity of the rock to be tested that varies with depth and a permeability model corresponding to the lithology of the rock to be tested.

[0075] For example, after the permeability model of the lithology of the rock to be tested is determined in the above step S402, the porosity corresponding to the lithology 1 of the rock to be tested that varies with depth (assuming that 410 groups of porosity among the 600 groups of porosity correspond to lithology 1) is substituted into the permeability model PERM1=0.0002e POR1*0.8333 In the above equation, the corresponding 410 groups of permeability of lithology 1 can be obtained. Similarly, the 190 groups of porosity corresponding to lithology 3 of the rock to be tested that change with depth are respectively substituted into the permeability model PERM3=7E-0.5e POR3*1.0308 In the above equation, the corresponding 190 groups of permeabilities of lithology 3 can be obtained.

[0076] Combination Figure 4 , refer to the corresponding "skeleton density" in "rock analysis" (i.e. corresponding to DEN 骨架 (d)), we can see that at 4115m to 4122m underground, the corresponding skeleton density DEN 骨架 (d) Between the rock skeleton density b1 and b2, it can be determined to be lithology 1, i.e., fine-grained rock; between 4150m and 4169m underground, the corresponding skeleton density DEN 骨架 (d) It is between the rock skeleton density b2 and b3, so it can be determined to be lithology 3, i.e., conglomerate. (The actual scenario may also include other situations. For example, the lithology corresponding to the rock density collected at 4162 meters is fine sandstone, but the lithology corresponding to the rock density collected at 4163 meters is conglomerate, and at 4164 meters, the lithology corresponding to the rock density collected is fine sandstone. That is, the lithology of the formation is complex and may include multiple situations.)

[0077] After obtaining the permeability of each lithology (i.e., the permeability as a function of depth), the average permeability of multiple permeabilities belonging to the same lithology at a burial depth of 4115 meters to 4129 meters is averaged to determine the average permeability of the same lithology within the depth range. Similarly, the average permeability of multiple permeabilities belonging to the same lithology at a depth of 4150 meters to 4169 meters is averaged to determine the average permeability of the same lithology within the burial depth range.

[0078] According to the above method of the embodiment of the present invention, when studying complex lithology (including multiple lithologies) in actual situations, the lithology of the rock to be tested can be effectively identified, and the permeability can be determined by lithology. Compared with the existing permeability that can only study a single lithology, the embodiment of the present invention can effectively identify the lithology of the rock to be tested, thereby determining the permeability by lithology, thereby improving the accuracy of permeability calculation, and can well meet the requirements of fine evaluation of oil and gas fields.

[0079] Through the above technical scheme, according to the multiple porosities and multiple rock densities corresponding to each of the multiple lithologies of the rock sample, the rock skeleton density corresponding to each lithology of the rock sample is constructed. This step provides an important basis for the subsequent determination of the lithology of the rock to be tested; according to the multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample, a permeability model corresponding to each lithology of the rock sample is constructed. The main purpose of this step is to determine the permeability model corresponding to the lithology of the rock to be tested after the lithology of the rock to be tested is determined; according to the components of the rock to be tested, the permeability of the rock to be tested with depth is determined. The porosity changes; and according to the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that changes with depth, and the porosity of the rock to be tested that changes with depth, the permeability corresponding to the lithology of the rock to be tested is determined, that is, after the lithology of the rock to be tested is determined in the above steps, the permeability model corresponding to the lithology can be determined accordingly, and finally the known porosity of the rock to be tested that changes with depth is substituted into the corresponding permeability model, and the permeability corresponding to the lithology of the rock to be tested can be determined. Therefore, the present invention can effectively identify multiple lithologies of rocks under complex lithology conditions, thereby determining the permeability corresponding to each of the multiple lithologies, thereby improving the calculation accuracy of the permeability.

[0080] refer to Figure 4 The figure is a comparison chart between the permeability corresponding to each lithology determined by the inventor according to the above permeability determination method and the permeability determined by the prior art. Among them, the "skeleton density" curve in the seventh "rock analysis" channel is the rock skeleton density DEN of the rock to be tested that changes with depth. 骨架 (d) The “POR” curve in the eighth track “Porosity” is the porosity calculated using the embodiment of the present invention, and the “PERM” curve in the ninth track is the permeability determined using the embodiment of the present invention.

[0081] Effect analysis: Figure 4The "PERM" in the ninth track is the permeability curve calculated by the method of the present invention, and the "PERMY" is the permeability curve calculated by the prior art. The rod-shaped "core permeability" in the same track is the sample collected from the actual drilling coring, which serves as a reference standard for calculating whether the permeability is accurate. Figure 4 It can be seen from the permeability comparison of the ninth track that the permeability "PERM" curve determined by using the embodiment of the present invention is more consistent with the core permeability. For specific data comparison, please refer to Table 3.

[0082] In Table 3, the upper part of layer 15 in track 11 (corresponding to a depth of 4116-4122 meters) has an average permeability of about 0.65 mD (millidarcy) determined by the method for determining the permeability provided by the embodiment of the present invention; the lower part of layer 15 (corresponding to a depth of 4122-4128 meters) has an average permeability of about 5.1 mD (millidarcy) determined by the method for determining the permeability provided by the embodiment of the present invention. The upper part of layer 16 (corresponding to a depth of 4150-4158 meters) has an average permeability of about 116.1 mD (millidarcy) determined by the method for determining the permeability provided by the embodiment of the present invention; the lower part of layer 16 (corresponding to a depth of 4158-4168.5 meters) has an average permeability of about 5.7 mD (millidarcy) determined by the method for determining the permeability provided by the embodiment of the present invention. It can be seen from the table that the absolute error of the permeability determined by the prior art is much greater than the absolute error of the permeability determined by the present invention. Therefore, it can be concluded that the accuracy of the permeability determined by the embodiment of the present invention is greatly improved compared with the accuracy of the permeability determined by the prior art.

[0083]

[0084] Table 3 Absolute error comparison table between the present invention and the prior art

[0085] On the other hand, the present invention also provides a permeability determination system, which includes: a first acquisition module, used to determine the rock skeleton density corresponding to each lithology of the rock sample based on multiple porosities and multiple rock densities corresponding to each lithology of the multiple lithologies of the rock sample; a second acquisition module, used to construct a permeability model corresponding to each lithology of the rock sample based on the multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample; a first determination module, used to determine the rock skeleton density of the rock to be tested that varies with depth and the porosity of the rock to be tested that varies with depth based on the rock components to be tested; and a second determination module, used to determine the permeability corresponding to the lithology of the rock to be tested based on the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that varies with depth, and the porosity of the rock to be tested that varies with depth.

[0086] For details on the determination of the above permeability and its effects, please refer to the relevant description of the above permeability determination method, which will not be repeated here.

[0087] In yet another aspect, the present invention further provides a machine-readable storage medium having stored thereon instructions for executing the above-mentioned method for determining the permeability.

[0088] For details on the determination of the above permeability and its effects, please refer to the relevant description of the above permeability determination method, which will not be repeated here.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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 A step that specifies a function in one or more boxes.

[0093] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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 permeability, characterized in that: The determination method comprises: Determine the rock skeleton density corresponding to each lithology of the rock sample according to a plurality of porosities and a plurality of rock densities corresponding to each lithology of the rock sample; Constructing a permeability model corresponding to each lithology of the rock sample according to a plurality of porosities and a plurality of permeabilities corresponding to each lithology of the rock sample; Determining the rock skeleton density of the rock to be tested and the porosity of the rock to be tested as it changes with depth according to the rock components to be tested; and The permeability corresponding to the lithology of the rock to be tested is determined based on the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that changes with depth, and the porosity of the rock to be tested that changes with depth.

2. The method for determining permeability according to claim 1, characterized in that: Determining the rock skeleton density corresponding to each lithology of the rock sample according to the multiple porosities and the multiple rock densities corresponding to each lithology of the rock sample includes: According to the multiple porosities and multiple rock densities corresponding to the lithology i of the rock sample, the rock skeleton density b corresponding to the lithology i is determined. i : DEN=a i BY+b i , Wherein, DENi is a plurality of rock densities corresponding to the lithology i of the rock sample, POR is a plurality of porosities corresponding to the lithology i of the rock sample, a i and b i are the linear fitting coefficients corresponding to the lithology i of the rock sample.

3. The method for determining permeability according to claim 1, characterized in that: The step of constructing a permeability model corresponding to each lithology of the rock sample according to the multiple porosities and multiple permeabilities corresponding to each lithology of the rock sample comprises: According to a plurality of porosities and a plurality of permeabilities corresponding to the lithology i of the rock sample, a permeability model corresponding to the lithology i of the rock sample is constructed, Where PERMi is the permeability corresponding to the lithology i of the rock sample, c i and i are all fitting coefficients corresponding to the lithology i of the rock sample.

4. The method for determining permeability according to claim 1, characterized in that: The step of determining the rock skeleton density of the rock to be tested and the porosity of the rock to be tested that varies with depth according to the rock components to be tested comprises: According to the rock components to be tested, construct a rock component equation group of the rock to be tested; Determining the rock skeleton density of the rock to be tested that varies with depth according to the rock component equation group of the rock to be tested; and The porosity of the rock to be tested that varies with depth is determined based on the rock skeleton density of the rock to be tested that varies with depth.

5. The method for determining permeability according to claim 4, characterized in that: The rock components include: silica, calcium and mud. Accordingly, constructing the rock component equation group according to the rock components includes: V 硅质 (d)×DEN 硅质 +V 钙质 (d)×DEN 钙质 +V 泥质 (d)×DEN 泥质 +POR es (d)×DEN 流体 =DEN(d), V 硅质 (d)×AC 硅质 +V 钙质 (d)×AC 钙质 +V 泥质 (d)×AC 泥质 +FOR es (d)×AC 流体 =AC(d), V 泥质 (d)×CNL 硅质 +V 钙质 (d)×CNL 钙质 +V 泥质 (d)×CNL 泥质 +POR es (d)×CNL 流体 =CNL(d), V 硅质 (d)+V 钙质 (d)+V 泥质 (d)+POR es (d)=1, Among them, V 硅质 (d) V 钙质 (d) V 泥质 (d) is the volume percentage of siliceous, calcareous and argillaceous materials with depth; DEN 硅质 、DEN 钙质 、DEN 泥质 、DEN 流体 are the density characteristic values ​​of siliceous, calcareous, muddy and fluid respectively; AC 硅质 , AC 钙质 , AC 泥质 , AC 流体 are the acoustic time difference characteristic values ​​of siliceous, calcareous, muddy and fluid respectively; CNL 硅质 、CNL 钙质 、CNL 泥质 、CNL 流体 are the neutron characteristic values ​​of siliceous, calcareous, argillaceous and fluid respectively; DEN(d) is the compensated density logging value of the rock to be tested that varies with depth; AC(d) is the compensated acoustic time difference logging value of the rock to be tested that varies with depth; CNL(d) is the compensated neutron logging value of the rock to be tested that varies with depth; POR es (d) is the estimated porosity of the rock to be tested that varies with depth.

6. The method for determining permeability according to claim 5, characterized in that: Determining the rock skeleton density of the rock to be tested that varies with depth according to the rock component equation group to be tested includes: According to the rock component equation group to be tested, the volume percentage V of the silica in the rock to be tested that varies with depth is determined. 硅质 (d) The volume percentage V of the calcium content of the rock to be tested as it changes with depth 钙质 (d); According to the volume percentage V of the silica of the rock to be tested that changes with depth 硅质 (d) The volume percentage V of the calcium content of the rock to be tested as it changes with depth 钙质 (d) and the following formula to determine the rock skeleton density DEN of the rock to be tested as it changes with depth: 骨架 (d): DEN 骨架 (d)=V 硅质 (d)×DEN 硅质 +V 钙质 (d)×DEN 钙质 +V 泥质 (d)×DEN 泥质 。 7. The method for determining permeability according to claim 6, characterized in that: According to the rock skeleton density DEN of the rock to be tested that changes with depth 骨架 (d) and the following formula, determining the porosity POR(d) of the rock to be tested as it changes with depth includes:

8. The method for determining permeability according to claim 7, characterized in that: Determining the permeability of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, and the porosity of the rock to be tested that varies with depth includes: Determine the lithology of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample and the rock skeleton density of the rock to be tested that varies with depth; Determining a permeability model corresponding to the lithology of the rock to be tested from the permeability models corresponding to each lithology of the rock sample; and The permeability corresponding to the lithology of the rock to be tested is determined according to the porosity of the rock to be tested that varies with depth and a permeability model corresponding to the lithology of the rock to be tested.

9. The method for determining permeability according to claim 8, characterized in that: Determining the lithology of the rock to be tested according to the rock skeleton density corresponding to each lithology of the rock sample and the rock skeleton density of the rock to be tested that varies with depth includes: When the rock skeleton density of the rock to be tested changes with depth, the rock skeleton density b i To b i+1 When , the type of lithology is determined to be lithology i.

10. A system for determining permeability, characterized in that: The determination system comprises: A first acquisition module is used to determine the rock skeleton density corresponding to each lithology of the rock sample according to a plurality of porosities and a plurality of rock densities corresponding to each lithology of the rock sample; A second acquisition module is used to construct a permeability model corresponding to each lithology of the rock sample according to a plurality of porosities and a plurality of permeabilities corresponding to each lithology of the rock sample; A first determination module is used to determine the rock skeleton density of the rock to be tested that varies with depth and the porosity of the rock to be tested that varies with depth according to the rock components to be tested; and The second determination module is used to determine the permeability corresponding to the lithology of the rock to be tested based on the rock skeleton density corresponding to each lithology of the rock sample, the permeability model corresponding to each lithology of the rock sample, the rock skeleton density of the rock to be tested that changes with depth, and the porosity of the rock to be tested that changes with depth.

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