Method for calculating porosity-permeability relationship of on-off carbonate reservoir

Abstract

The present application belongs to the technical field of oil and gas exploration and development, and particularly relates to a method for calculating the porosity-permeability relationship of faulted and controlled carbonate rock oil and gas reservoirs, comprising: S1: selecting the type of faulted and controlled carbonate rock oil and gas reservoirs; S2: preliminarily establishing the corresponding values of porosity and permeability of single wells of three types of oil and gas reservoirs; S3: fitting to obtain the fitting relationship between the water absorption index and the permeability of single wells of cave type and fracture hole type oil and gas reservoirs; S4: fitting to obtain the fitting relationship between the leakage rate and the permeability of single wells of oil and gas reservoirs; S5: establishing the correlation relationship of the leakage rate under the same porosity of single wells of cave type and fracture type oil and gas reservoirs; and S6: determining the porosity-permeability correlation relationship of different types of oil and gas reservoirs. The present application can determine the porosity-permeability correlation relationship of all types of reservoirs, and solves the problem that the current obtained porosity and permeability of reservoirs mostly come from cave type and fracture hole type, and cannot effectively cover all types of reservoirs.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas exploration and development technology, specifically relating to a method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs. Background Technology

[0002] The Shunbei fault-controlled carbonate oil and gas reservoir is primarily influenced by fault zones, resulting in a complex spatial structure and highly random distribution of internal fracture zones. This leads to diverse reservoir types, comprising cavernous structures, fractured pores, and fractures of varying scales. The reservoir structure exhibits strong heterogeneity, with varying degrees of leakage and venting occurring during drilling. Well logging reveals the development of fractured-vuggy aggregates of different sizes around the well. Conventional methods employ statistical relationships, with the Timur formula being a good example of field applicability; however, it has certain limitations in practical applications to the Shunbei fault-controlled reservoir.

[0003] For the highly heterogeneous fault-controlled reservoirs in the Shunbei area, effective porosity is primarily obtained through well logging interpretation, and permeability-related parameters are derived through well testing interpretation. However, the Timur formula or direct fitting is not highly specific for the strong heterogeneity of different reservoir types. Currently obtained reservoir porosity and permeability data mostly come from cavernous and fractured-vuggy reservoirs, failing to effectively cover all reservoir types. Further calculation methods are needed to refine the current sample data. Therefore, for the fault-controlled carbonate reservoirs in the Shunbei oil and gas field, a more adaptable porosity-permeability conversion method is urgently needed to provide effective guidance for subsequent reservoir modeling. Summary of the Invention

[0004] This invention addresses the problem that most of the currently obtained reservoir porosity and permeability data come from cavernous and fractured-vuggy reservoirs, failing to effectively cover all reservoir types. It proposes a method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs. The method involves statistically comparing porosity and permeability data of three different reservoir types (cavrnous, fractured-vuggy, and fractured) in fault-controlled carbonate oil and gas reservoirs, and finally determining the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs after data fitting.

[0005] The technical solution claimed by this invention is as follows:

[0006] A method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs includes the following steps:

[0007] S1: Select the type of fault-controlled carbonate oil and gas reservoir, which includes: cavern-like type, fracture-vuggy type, and fracture type;

[0008] S2: For different types of oil and gas reservoirs selected in S1, the porosity value of each single well in each oil and gas reservoir is determined based on the logging interpretation results. The permeability value of each single well in each oil and gas reservoir is obtained based on the interpretation results of the corresponding unsteady well test data. The corresponding values ​​of porosity and permeability of single wells in the three types of oil and gas reservoirs are initially established.

[0009] S3: Based on the corresponding values ​​of porosity and permeability mentioned in S2, for water-injected oil wells, the correlation between water absorption index and permeability of single wells in cavernous and fractured-pore type oil and gas reservoirs is established through the dynamic characteristics of water injection in oil wells. The fitting relationship between water absorption index and permeability of single wells in cavernous and fractured-pore type oil and gas reservoirs is obtained by fitting the correlation relationship. The permeability of the corresponding single well with water absorption index is supplemented by the fitting relationship.

[0010] S4: Based on the corresponding values ​​of porosity and permeability mentioned in S2, for oil wells without water injection, establish the correlation between leakage rate and permeability of single wells in different types of oil and gas reservoirs, and obtain the fitting relationship between leakage rate and permeability of single wells in oil and gas reservoirs based on the correlation. The permeability of corresponding single wells without water absorption index is supplemented by the fitting relationship.

[0011] S5: Establish the correlation formula for leakage velocity of single wells in cavernous and fractured oil and gas reservoirs under the same porosity, and then obtain the correlation formula for permeability of single wells in cavernous and fractured oil and gas reservoirs.

[0012] S6: Determine the correlation between porosity and permeability of different types of oil and gas reservoirs: Based on the porosity and permeability of single wells in cavernous and fractured-void oil and gas reservoirs obtained in S3 and S4, determine the correlation formulas between porosity and permeability of single wells in cavernous and fractured-void oil and gas reservoirs, respectively; Based on the correlation obtained in S5 and combined with the correlation formula between porosity and permeability of single wells in cavernous oil and gas reservoirs, obtain the correlation formula between porosity and permeability of single wells in fractured oil and gas reservoirs.

[0013] Preferably, S1 determines the reservoir type of fault-controlled carbonate oil and gas reservoir by combining static well carving and production dynamics.

[0014] Preferably, the water absorption index and permeability in S3 have a good linear positive correlation; the dynamic characteristics of water injection in oil wells described in S3 are that the higher the reservoir permeability, the greater the water absorption index.

[0015] Preferably, leakage rate and porosity in S4 have a good correlation.

[0016] The correlation formula for leakage velocity in single wells of cavernous and fractured oil and gas reservoirs in S5 under the same porosity is as follows:

[0017] y = 0.1341x 2 -0.4098x+1.0092

[0018] Where: y represents the leakage rate of a single well in a fractured oil and gas reservoir; x represents the leakage rate of a single well in a cavernous oil and gas reservoir.

[0019] The permeability correlation formulas for single wells in S5 cavernous and fractured oil and gas reservoirs are as follows:

[0020] k 缝 =0.1341k 洞 2 -0.4098k 洞 +1.0092

[0021] Where: k 缝 k represents the permeability of a single well in a fractured oil and gas reservoir. 洞 This indicates the permeability of a single well in a cavernous oil and gas reservoir.

[0022] The correlation between porosity and permeability of a single well in a cavernous oil and gas reservoir in S6 is as follows:

[0023]

[0024] Where: k 洞 This indicates the permeability of a single well in a cavernous oil and gas reservoir. This indicates the porosity of a single well in a cavernous oil and gas reservoir.

[0025] In a specific embodiment of the present invention, the correlation formula between porosity and permeability of a single well in a cavernous oil and gas reservoir is substituted into the correlation formula between permeability of a single well in a cavernous and fractured oil and gas reservoir to obtain the correlation formula between porosity and permeability of a single well in a fractured oil and gas reservoir.

[0026] The correlation between porosity and permeability of a single well in a fractured oil and gas reservoir is as follows:

[0027]

[0028] Where: k 缝 This indicates the permeability of a single well in a fractured oil and gas reservoir. This indicates the porosity of a single well in a fractured oil and gas reservoir.

[0029] The correlation between porosity and permeability of a single well in a fractured-vuggy oil and gas reservoir in S6 is as follows:

[0030]

[0031] Where: k 裂缝孔洞This indicates the permeability of a single well in a fractured and porous oil and gas reservoir. This indicates the porosity of a single well in a fractured and porous oil and gas reservoir.

[0032] Beneficial effects:

[0033] This invention provides a method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs. First, the reservoir type of the fault-controlled carbonate oil and gas reservoir is selected. Then, for the selected reservoir type, based on well logging interpretation results and unsteady gauging test data interpretation results, the corresponding values ​​of porosity and permeability for single wells in the three types of reservoirs are initially established. The permeability of the initially established single wells in cavernous and fractured-vuggy oil and gas reservoirs is optimized and improved using the correlation between the water absorption index and permeability of single wells in the reservoir. Permeability values ​​of corresponding single wells with water absorption indices are added, increasing the number of sample points. Finally, the correlation between leakage rate and permeability of single wells in the three types of oil and gas reservoirs is used to further refine the calculation of the porosity and permeability of single wells in the three types of reservoirs. The permeability of the reservoir is optimized and improved. Simultaneously, a correlation formula for leakage velocity under the same porosity in single wells of cavernous and fractured oil and gas reservoirs is established, thereby obtaining the permeability correlation formula for single wells of cavernous and fractured oil and gas reservoirs. Using the porosity and permeability data of single wells of cavernous and fractured-pore type oil and gas reservoirs obtained above, the correlation formulas for porosity and permeability of single wells of cavernous and fractured-pore type oil and gas reservoirs are determined respectively. Based on the permeability correlation formulas of cavernous and fractured oil and gas reservoirs, combined with the porosity and permeability correlation formulas of single wells of cavernous oil and gas reservoirs, the correlation formula for porosity and permeability of single wells of fractured oil and gas reservoirs is obtained. In summary, this invention can determine the correlation between porosity and permeability of three different reservoir types (cavrnous, fractured-pore, and fractured) in fault-controlled carbonate oil and gas reservoirs, solving the problem that currently obtained reservoir porosity and permeability data are mostly from cavernous and fractured-pore types, failing to effectively cover all reservoir types.

[0034] In S3, the water absorption index and permeability have a good linear positive correlation. For a single well that has been injected with water but whose permeability is unknown, the permeability of the single well can be determined by the correlation between the water absorption index and permeability.

[0035] In S4, leakage velocity and porosity have a good correlation. For a single well without water injection but with unknown permeability, the permeability of the single well can be determined based on the correlation between leakage velocity and porosity. Attached Figure Description

[0036] Figure 1 This is a flowchart of the present invention.

[0037] Figure 2 This is a graph showing the correlation between water absorption index and permeability of a single well in a cave-like (left) and fracture-vuggy (right) oil and gas reservoir collective in an embodiment of the present invention.

[0038] Figure 3 This is a curve showing the fitting relationship between water absorption index and permeability of a single well in a cave-like and fractured-pore type oil and gas reservoir according to an embodiment of the present invention.

[0039] Figure 4 This is a fitting diagram of the leakage rate and permeability of a single well in a different type of oil and gas reservoir in an embodiment of the present invention.

[0040] Figure 5 This is a graph showing the correlation between leakage velocity in a single well of a cave-type and fractured oil and gas reservoir with the same porosity, as described in an embodiment of the present invention.

[0041] Figure 6 These are curves showing the correlation between porosity and permeability of different types of oil and gas reservoirs in embodiments of the present invention; the left side represents the correlation between porosity and permeability of a single well in a cavernous oil and gas reservoir; the upper right side represents the correlation between porosity and permeability of a single well in a fractured and cavernous oil and gas reservoir; and the lower right side represents the correlation between porosity and permeability of a single well in a fractured oil and gas reservoir. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings:

[0043] A method for calculating the porosity-permeability relationship in fault-controlled carbonate oil and gas reservoirs, such as Figure 1 As shown, it includes the following steps:

[0044] S1: Combining static well carving and production dynamics, select the type of fault-controlled carbonate oil and gas reservoir. The types of oil and gas reservoirs include: cavern-like type, fracture-vuggy type, and fracture type.

[0045] S2: For the different types of oil and gas reservoirs selected in S1, the porosity value of each oil and gas reservoir is determined based on the logging interpretation results. The permeability value of each oil and gas reservoir is obtained based on the interpretation results of the corresponding unsteady well test data, as shown in Table 1. The corresponding values ​​of porosity and permeability of the three types of oil and gas reservoirs are initially established.

[0046] Table 1. Correlation between porosity and permeability

[0047]

[0048] S3: Based on the corresponding values ​​of porosity and permeability described in S2, for water-injected oil wells, through the dynamic characteristics of water injection in the oil well, such as... Figure 2As shown, the correlation between water absorption index and permeability of single wells in cavernous and fractured-pore type oil and gas reservoirs is established respectively. The fitting formulas for the water absorption index and permeability of single wells in cavernous and fractured-pore type oil and gas reservoirs are obtained by fitting these correlations. Figure 3 The permeability of the corresponding single well with water absorption index is supplemented by the fitted relationship, and the supplemented permeability data is shown in Table 2; the dynamic characteristic of water injection in oil wells is that the higher the reservoir permeability, the greater the water absorption index.

[0049] Table 2 shows the fitted relationship between water absorption index and permeability. (Supplementary data: permeability of a single well.)

[0050]

[0051] Among them, the water absorption index has a good linear positive correlation with permeability, and can be used to supplement the permeability of single wells that have been injected with water but whose permeability is unknown.

[0052] S4: Based on the corresponding values ​​of porosity and permeability described in S2, for oil wells without water injection, such as... Figure 4 As shown, the correlation between leakage rate and permeability of single wells in different types of oil and gas reservoirs is established respectively. Based on the correlation, the fitting relationship between leakage rate and permeability of single wells in oil and gas reservoirs is obtained. The permeability of corresponding single wells without water absorption index is supplemented by the fitting relationship.

[0053] Among them, leakage rate and porosity have a good correlation and can be used to supplement the permeability of single wells without water injection but with unknown permeability.

[0054] S5: As Figure 5 As shown, the correlation between leakage velocity of single wells in cavernous and fractured oil and gas reservoirs under the same porosity is established, and then the correlation between permeability of single wells in cavernous and fractured oil and gas reservoirs is obtained.

[0055] The correlation between leakage velocity in single wells of cavernous and fractured oil and gas reservoirs under the same porosity is as follows:

[0056] y = 0.1341x 2 -0.4098x+1.0092

[0057] Where: y represents the leakage rate of a single well in a fractured oil and gas reservoir; x represents the leakage rate of a single well in a cavernous oil and gas reservoir.

[0058] The above calculation formula is based on the same porosity of a single well. Therefore, the permeability relationship of a single well in a cavernous and fractured oil and gas reservoir is as follows:

[0059] k 缝 =0.1341k 洞2 -0.4098k 洞 +1.0092

[0060] Where: k 缝 k represents the permeability of a single well in a fractured oil and gas reservoir. 洞 This indicates the permeability of a single well in a cavernous oil and gas reservoir.

[0061] S6: As Figure 6 As shown, the correlation between porosity and permeability of different types of oil and gas reservoirs is determined: the porosity and permeability of single wells in cavernous and fractured-cavity oil and gas reservoirs obtained from S3 and S4 are used to determine the correlation formulas between porosity and permeability of single wells in cavernous and fractured-cavity oil and gas reservoirs, respectively; based on the correlation obtained from S5 and combined with the correlation formula between porosity and permeability of single wells in cavernous oil and gas reservoirs, the correlation formula between porosity and permeability of single wells in fractured oil and gas reservoirs is obtained.

[0062] The correlation between porosity and permeability of a single well in a cavern-type oil and gas reservoir is as follows:

[0063]

[0064] Where: k 洞 This indicates the permeability of a single well in a cavernous oil and gas reservoir. This indicates the porosity of a single well in a cavernous oil and gas reservoir.

[0065] Substituting the correlation formula between porosity and permeability of a single well in a cavernous oil and gas reservoir into the correlation formula between permeability of a single well in a cavernous and fractured oil and gas reservoir, the correlation formula between porosity and permeability of a single well in a fractured oil and gas reservoir is obtained as follows:

[0066]

[0067] Where: k 缝 This indicates the permeability of a single well in a fractured oil and gas reservoir. This indicates the porosity of a single well in a fractured oil and gas reservoir.

[0068] The correlation between porosity and permeability of a single well in a fractured-vuggy oil and gas reservoir is as follows:

[0069]

[0070] Where: k 裂缝孔洞 This indicates the permeability of a single well in a fractured and porous oil and gas reservoir. This indicates the porosity of a single well in a fractured and porous oil and gas reservoir.

Claims

1. A method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs, characterized in that, Includes the following steps: S1: Select the type of fault-controlled carbonate oil and gas reservoir, which includes: cavern-like type, fracture-vuggy type, and fracture type; S2: For different types of oil and gas reservoirs selected in S1, the porosity value of each single well in each oil and gas reservoir is determined based on the logging interpretation results. The permeability value of each single well in each oil and gas reservoir is obtained based on the interpretation results of the corresponding unsteady well test data. The corresponding values ​​of porosity and permeability of single wells in the three types of oil and gas reservoirs are initially established. S3: Based on the corresponding values ​​of porosity and permeability mentioned in S2, for water-injected oil wells, the correlation between water absorption index and permeability of single wells in cavernous and fractured-pore type oil and gas reservoirs is established through the dynamic characteristics of water injection in oil wells. The fitting relationship between water absorption index and permeability of single wells in cavernous and fractured-pore type oil and gas reservoirs is obtained by fitting the correlation relationship. The permeability of the corresponding single well with water absorption index is supplemented by the fitting relationship. S4: Based on the corresponding values ​​of porosity and permeability mentioned in S2, for oil wells without water injection, establish the correlation between leakage rate and permeability of single wells in different types of oil and gas reservoirs, and obtain the fitting relationship between leakage rate and permeability of single wells in oil and gas reservoirs based on the correlation. The permeability of corresponding single wells without water absorption index is supplemented by the fitting relationship. S5: Establish the correlation formula for leakage velocity in single wells of cavernous and fractured oil and gas reservoirs under the same porosity, and then obtain the correlation formula for permeability in single wells of cavernous and fractured oil and gas reservoirs; the correlation formula for leakage velocity in single wells of cavernous and fractured oil and gas reservoirs under the same porosity is as follows: y = 0.1341x 2 - 0.4098x + 1.0092 Where: y represents the leakage rate of a single well in a fractured oil and gas reservoir; x represents the leakage rate of a single well in a cavernous oil and gas reservoir. The permeability correlation formulas for single wells in cavernous and fractured oil and gas reservoirs are as follows: Where: k 缝 k represents the permeability of a single well in a fractured oil and gas reservoir. 洞 Indicates the permeability of a single well in a cavern-type oil and gas reservoir. S6: Determine the correlation between porosity and permeability of different types of oil and gas reservoirs: Based on the porosity and permeability of single wells in cavernous and fractured-cavity oil and gas reservoirs obtained in S3 and S4, determine the correlation formulas between porosity and permeability of single wells in cavernous and fractured-cavity oil and gas reservoirs, respectively; Based on the correlation obtained in S5 and combined with the correlation formula between porosity and permeability of single wells in cavernous oil and gas reservoirs, obtain the correlation formula between porosity and permeability of single wells in fractured oil and gas reservoirs; The correlation between porosity and permeability of a single well in a cavernous oil and gas reservoir is as follows: in: This indicates the permeability of a single well in a cavernous oil and gas reservoir. This indicates the porosity of a single well in a cavernous oil and gas reservoir. The correlation between porosity and permeability of a single well in a fractured oil and gas reservoir is as follows: in: This indicates the permeability of a single well in a fractured oil and gas reservoir. This indicates the porosity of a single well in a fractured oil and gas reservoir.

2. The method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs according to claim 1, characterized in that, The S1 determines the reservoir type of fault-controlled carbonate oil and gas reservoirs by combining static well carving with production dynamics.

3. The method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs according to claim 1, characterized in that, In S3, the water absorption index and permeability have a good linear positive correlation; the dynamic characteristics of water injection in oil wells described in S3 are that the higher the reservoir permeability, the greater the water absorption index.

4. The method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs according to claim 1, characterized in that, In S4, leakage velocity and porosity show a good correlation.

5. The method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs according to claim 1, characterized in that, By substituting the correlation formula between porosity and permeability of a single well in a cavernous oil and gas reservoir into the correlation formula between permeability of a single well in a cavernous and fractured oil and gas reservoir, the correlation formula between porosity and permeability of a single well in a fractured oil and gas reservoir is obtained.

6. The method for calculating the porosity-permeability relationship of fault-controlled carbonate oil and gas reservoirs according to claim 1, characterized in that, The correlation between porosity and permeability of a single well in a fractured-vuggy oil and gas reservoir in S6 is as follows: in: This indicates the permeability of a single well in a fractured and porous oil and gas reservoir. This indicates the porosity of a single well in a fractured and porous oil and gas reservoir.

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