Saturation calculation method and system for carbonate reservoir and medium

Abstract

The invention discloses a carbonate reservoir saturation calculation method and system and a medium. The method is improved on the basis of a traditional high-contrast oil reservoir development mode, oil reservoir lithofacies water saturation is established through a non-communicated porosity curve, and a pore space fluid combination simplified volume model of a carbonate reservoir is constructed. Calculating the real water saturation of the carbonate reservoir by combining the first result curve, the second result curve and the oil reservoir lithofacies water saturation; the problem that due to the fact that low-resistance block masses are developed in the carbonate rock oil layer, the resistivity of the oil layer is too low, and then omission is caused is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of reservoir parameter calculation, and particularly relates to a method, system and medium for calculating the saturation of a carbonate reservoir. Background Art

[0002] During the development of oil and gas fields, the geological characteristics and reservoir conditions of different oil and gas blocks often vary significantly. Especially for carbonate oil reservoirs, their complexity and heterogeneity are particularly prominent. The traditional high-contrast oil reservoir development mode is mainly designed for high-resistivity oil reservoirs, and conventional means such as resistivity logging are used to identify oil reservoirs and calculate the water saturation of reservoirs. However, this development mode has obvious limitations when facing carbonate oil reservoirs.

[0003] In carbonate oil reservoirs, massive structures with low resistivity often develop. Due to the particularity of mineral composition, pore structure or fluid distribution in these masses, the overall resistivity of the oil reservoir is significantly reduced. Under the traditional development mode, low-resistivity oil reservoirs are easily misjudged as water layers or low-yield layers and thus omitted during the development process. This misjudgment not only leads to waste of oil and gas resources, but also causes the calculated result of the reservoir water saturation to deviate seriously from the actual value, thereby affecting the formulation and adjustment of development plans.

[0004] In addition, the heterogeneity of carbonate oil reservoirs makes the spatial distribution of reservoir parameters extremely complex, and it is difficult for the traditional high-contrast oil reservoir development mode to accurately depict its true characteristics. For example, the presence of low-resistivity masses may lead to inconsistent logging interpretation results with the actual properties of the oil reservoir, thereby affecting reservoir evaluation and development effects. Therefore, continuing to use the traditional development mode not only cannot fully exert the potential of carbonate oil reservoirs, but may also cause resource waste and low development efficiency due to misjudgment and omission.

[0005] In summary, for complex reservoirs such as carbonate oil reservoirs, it is urgent to develop a new development mode that can adapt to their unique geological characteristics to accurately identify low-resistivity oil reservoirs and optimize the calculation method of reservoir water saturation, so as to improve the development efficiency and economic benefits of oil and gas resources. Summary of the Invention

[0006] The technical problem to be solved by the present invention is that for complex reservoirs such as carbonate oil reservoirs, the traditional high-contrast oil reservoir development mode is difficult to accurately identify low-resistivity oil reservoirs and optimize the calculation method of reservoir water saturation. The purpose of the present invention is to provide a method, system and medium for calculating the saturation of a carbonate reservoir, which improves the method on the basis of the traditional high-contrast oil reservoir development mode, and establishes the water saturation S of the reservoir lithofacies through the non-connected porosity POR non curve w, a simplified volume model of the pore space fluid combination of the carbonate reservoir is constructed, combined with the first result curve, the second result curve and the water saturation S of the oil reservoir lithofacies w The true water saturation S of the carbonate reservoir is calculated w_R ; effectively solve the situation that the resistivity of the oil reservoir is too low due to the development of low-resistance masses in the carbonate oil reservoir, and thus it is omitted.

[0007] The present invention is realized through the following technical solutions:

[0008] This solution provides a method for calculating the saturation of a carbonate reservoir, including:

[0009] Obtain the neutron density curve, sonic curve and core sweep photograph of the carbonate reservoir;

[0010] Based on the neutron and density curves, calculate the total porosity Φ of the carbonate reservoir nd curve, and based on the sonic curve, calculate the sonic porosity Φ of the carbonate reservoir s curve;

[0011] According to the total porosity Φ nd curve and the sonic porosity Φ s curve, draw the non-connected porosity POR non curve;

[0012] Perform the first preprocessing and the second preprocessing on the core sweep photograph to obtain the first result curve and the second result curve respectively;

[0013] According to the non-connected porosity POR non curve, establish the water saturation S of the oil reservoir lithofacies w ;

[0014] Construct a simplified volume model of the pore space fluid combination of the carbonate reservoir, combined with the first result curve, the second result curve and the water saturation S of the oil reservoir lithofacies w Calculate the true water saturation S of the carbonate reservoir w_R .

[0015] A further optimized solution is that the drawing method of the non-connected porosity POR non curve includes:

[0016] According to the formula Φ nd -Φ s Draw the non-connected porosity POR non curve. When Φ nd <Φ s appears, let the non-connected porosity POR non =0.

[0017] A further optimized solution is that the first preprocessing and the second preprocessing are respectively performed on the core rolling-scan photos to obtain a first result curve and a second result curve; the method includes:

[0018] Perform binary scanning on the core rolling-scan photos to identify the dry layer lithofacies area and the oil layer lithofacies area;

[0019] Filter the curve of the ratio of the dry layer lithofacies area to the total core area to obtain a first result curve, and filter the curve of the ratio of the oil layer lithofacies area to the total core area to obtain a second result curve.

[0020] A further optimized solution is that the oil layer lithofacies water saturation S non is established according to the non-connected porosity POR w curve; the method includes:

[0021] Establish a parallel conductive model based on the dry layer lithofacies and the oil layer lithofacies:

[0022]

[0023] Where: R oil represents the resistivity of the oil layer part; R dry represents the resistivity of the dry layer part; R t represents the resistivity of the deep logging detection; M represents the ratio of the oil layer lithofacies area to the total core area; N represents the ratio of the dry layer lithofacies area to the total core area;

[0024] Derive the oil layer lithofacies water saturation S w according to the parallel conductive model and Archie's formula.

[0025] A further optimized solution is that during the process of deriving the oil layer lithofacies water saturation S w according to the parallel conductive model and Archie's formula:

[0026] If R oil < R t , or R dry ≤ N·R t , then force R oil = R t ;

[0027] If R oil > 4R t , then force R oil = 4R t .

[0028] A further optimized solution is that the oil layer lithofacies water saturation S w is:

[0029]

[0030] Among them, R w represents the formation water resistivity; Φ represents the total porosity calculated from the three porosity curves, a and m represent the cementation exponent; b and n represent the saturation exponent.

[0031] A further optimized solution is that the simplified volume model of the pore space fluid combination includes a dry layer pore part and an oil layer pore part; the dry layer pore part is completely filled with formation water, and the oil layer pore part is filled with oil and gas and formation water.

[0032] A further optimized solution is that the true water saturation S of the carbonate reservoir is calculated by combining the first result curve, the second result curve and the water saturation S of the oil layer lithofacies w ; The method includes: w_R Based on the following formula, the formation water saturation of the simplified volume model of the pore space fluid combination is calculated as the true water saturation S of the carbonate reservoir

[0033] : w_R When S

[0034]

[0035] > S w_R > S w , then force S w_R = S w .

[0036] This solution also provides a saturation calculation system for carbonate reservoirs, which is used to implement the above-mentioned carbonate reservoir saturation calculation method based on resistivity correction; the system includes:

[0037] An acquisition module, which is used to obtain the neutron density curve, acoustic wave curve and core rolling and sweeping photos of the carbonate reservoir;

[0038] A first calculation module, which is used to calculate the total porosity Φ of the carbonate reservoir based on the neutron and density curves nd curve, and calculate the acoustic wave porosity Φ of the carbonate reservoir based on the acoustic wave curve s curve;

[0039] A drawing module, which is used to draw the non-connected porosity POR based on the total porosity Φ nd curve and the acoustic wave porosity Φ s curve; non curve;

[0040] A preprocessing module, which is used to perform the first preprocessing and the second preprocessing on the core rolling and sweeping photos respectively to obtain the first result curve and the second result curve;

[0041] A building module, which is used to establish based on the non-connected porosity POR nonCurve to establish the water saturation S of the reservoir lithofacies w ;

[0042] A second calculation module, configured to construct a simplified volume model of the pore space fluid combination of the carbonate reservoir, and calculate the true water saturation S of the carbonate reservoir by combining the first result curve, the second result curve, and the water saturation S of the reservoir lithofacies w for the carbonate reservoir w_R .

[0043] The present solution also provides a computer-readable medium, on which a computer program is stored. The computer program, when executed by a processor, can implement a method for calculating the saturation of a carbonate reservoir as described above

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects

[0045] 1. A method, system, and medium for calculating the saturation of a carbonate reservoir provided by the present invention; improving the method on the basis of the traditional high-contrast reservoir development mode. By establishing the water saturation of the reservoir lithofacies through the non-connected porosity curve, constructing a simplified volume model of the pore space fluid combination of the carbonate reservoir, and combining the first result curve, the second result curve, and the water saturation of the reservoir lithofacies to calculate the true water saturation of the carbonate reservoir; effectively solving the situation where the reservoir resistivity is too low due to the development of low-resistance masses in the carbonate reservoir, resulting in omission

[0046] 2. A method, system, and medium for calculating the saturation of a carbonate reservoir provided by the present invention; establishing the water saturation of the reservoir lithofacies according to the non-connected porosity curve, and constructing simplified reservoir models such as a simplified volume model of the pore space fluid combination of the carbonate reservoir, which can provide a reference for the logging interpretation of other low-resistance reservoirs BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings

[0048] Figure 1 is a schematic flow chart of the method for calculating the saturation of a carbonate reservoir

[0049] Figure 2 is a logging response characteristic diagram of the reservoir and the dry layer

[0050] Figure 3 is a comparison diagram of the logging response characteristics of the low-resistance reservoir and the conventional reservoir

[0051] Figure 4 It is a diagram for analyzing the origin of dry layers;

[0052] Figure 5 It is a diagram of the hypothetical model of isolated pore networks;

[0053] Figure 6 It is a diagram for identifying the oil-bearing property of cores;

[0054] Figure 7 It is for core well N and POR non Curve regression relationship diagram;

[0055] Figure 8 It is a diagram of a simplified resistivity conduction model;

[0056] Figure 9 It is a diagram of the calculation results of water saturation. Detailed implementation manners

[0057] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments and drawings. The illustrative implementation manners of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0058] For complex reservoirs such as carbonate rock oil layers, the traditional high-contrast oil layer development mode is difficult to accurately identify low-resistivity oil layers and optimize the calculation method of reservoir water saturation; in view of this, the following embodiments are provided in this solution to solve the above technical problems:

[0059] Embodiment 1

[0060] This embodiment provides a method for calculating the saturation of a carbonate rock reservoir, as Figure 1 shown, including:

[0061] Step 1: Obtain the neutron density curve, acoustic wave curve and core rolling and scanning photos of the carbonate rock reservoir;

[0062] Step 2: Calculate the total porosity Φ of the carbonate rock reservoir based on the neutron and density curves nd curve, and calculate the acoustic wave porosity Φ of the carbonate rock reservoir based on the acoustic wave curve s curve;

[0063] Step 3: Draw the non-connected porosity POR nd curve according to the total porosity Φ s curve and the acoustic wave porosity Φ non curve; The drawing method of the non-connected porosity POR non curve includes:

[0064] According to the formula Φ nd -Φs Plot the non-connected porosity POR non curve. When Φ nd <Φ s occurs, set the non-connected porosity POR non =0.

[0065] Step 4: Conduct the first preprocessing and the second preprocessing on the core rolling-scan photos respectively to obtain the first result curve and the second result curve; specifically, this step includes the following methods:

[0066] Perform binary scanning on the core rolling-scan photos to identify the dry layer lithofacies area and the oil layer lithofacies area; specifically, perform binary processing on the core rolling-scan photos with a 1 cm sampling interval.

[0067] Conduct filtering on the curve of the ratio of the dry layer lithofacies area to the total core area to obtain the first result curve, and conduct filtering on the curve of the ratio of the oil layer lithofacies area to the total core area to obtain the second result curve. The ratio N of the dry layer lithofacies area S dry to the total core area is: The ratio M of the oil layer lithofacies area S oil to the total core area is:

[0068] Optionally, perform 9-point filtering on N and M. The purpose of filtering is to match the sampling interval of the logging curve. In actual operation, the filtering parameters can be changed.

[0069] Optionally, for the first result curve, the purpose of establishing the regression relationship is to extend the empirical relationship obtained in the cored well to the non-cored section and non-cored wells, realizing the application based on pure logging curves; for the complete cored interval, this step can be omitted.

[0070] Step 5: Establish the water saturation S non of the oil layer lithofacies according to the non-connected porosity POR w curve; specifically, this step includes the following methods:

[0071] Establish a parallel conduction model based on the dry layer lithofacies and the oil layer lithofacies:

[0072]

[0073] Among them: R oil represents the resistivity of the oil layer part; R dry represents the resistivity of the dry layer part, and the deep detection resistivity measurement value of the overlying or underlying dry layer is used; R t represents the logging deep detection resistivity; M represents the ratio of the oil layer lithofacies area to the total core area; N represents the ratio of the dry layer lithofacies area to the total core area;

[0074] Transform the parallel conduction model into:

[0075] Based on the parallel conduction model and Archie's formula, the water saturation Sw of the reservoir lithofacies is derived w , in the process:

[0076] If R oil < R t , or R dry ≤ N·R t , then R is forced to be oil = R t ;

[0077] If R oil > 4R t , then R is forced to be oil = 4R t . Forcing the resistivity after correction not to be greater than 4 times R t is because for matrix-porous carbonate rocks, the saturation exponent n of Archie's formula is usually close to 2. Therefore, the well sections with resistivity higher than 4 times that of the water layer can generally be judged as oil layers. This setting of up to 4 times can be increased or decreased as appropriate according to the actual geological conditions of the research area.

[0078] Substitute the transformation formula of the parallel conduction model for the deep exploration resistivity curve R in Archie's formula t , to obtain the water saturation Sw of the reservoir lithofacies w :

[0079]

[0080] Archie's formula is

[0081] Among them, R w represents the resistivity of formation water; Φ represents the total porosity calculated by the triple porosity curve, a and m represent the cementation exponent; b and n represent the saturation exponent.

[0082] Step 6: Construct a simplified volume model of the pore space fluid combination of the carbonate reservoir, and combine the first result curve, the second result curve and the water saturation Sw of the reservoir lithofacies w to calculate the true water saturation Sw of the carbonate reservoir w_R . The simplified volume model of the pore space fluid combination includes a dry layer pore part and an oil layer pore part; all of the dry layer pore part is filled with formation water, and the oil layer pore part is filled with oil and gas and formation water.

[0083] The combination of the first result curve, the second result curve and the water saturation Sw of the reservoir lithofacies w to calculate the true water saturation Sw of the carbonate reservoir w_R ; includes the method:

[0084] Calculate the formation water saturation of the simplified volume model of the pore space fluid combination based on the following formula as the true water saturation S of the carbonate reservoir w_R :

[0085] S w_R = S w ·M + N;

[0086]

[0087] When S w_R > S w , then force S w_R = S w , and finally obtain the true water saturation S of the reservoir w_R .

[0088] Example 2

[0089] This example provides a saturation calculation system for carbonate reservoirs, which is used to implement the carbonate reservoir saturation calculation method based on resistivity correction described in Example 1; the system includes:

[0090] A collection module, used to obtain the neutron density curve, acoustic curve and core sweep photo of the carbonate reservoir;

[0091] A first calculation module, used to calculate the total porosity Φ nd curve of the carbonate reservoir based on the neutron and density curves, and calculate the acoustic porosity Φ s curve of the carbonate reservoir based on the acoustic curve;

[0092] A drawing module, used to draw the non-connected porosity POR nd curve according to the total porosity Φ s curve and the acoustic porosity Φ non curve;

[0093] A preprocessing module, used to perform the first preprocessing and the second preprocessing on the core sweep photo respectively to obtain the first result curve and the second result curve;

[0094] An establishment module, used to establish the water saturation S non of the oil reservoir lithofacies according to the non-connected porosity POR w curve;

[0095] A second calculation module, used to construct a simplified volume model of the pore space fluid combination of the carbonate reservoir, and calculate the true water saturation S w of the carbonate reservoir in combination with the first result curve, the second result curve and the water saturation S w_R of the oil reservoir lithofacies.

[0096] Example 3

[0097] This embodiment provides a computer-readable medium, on which a computer program is stored. When the computer program is executed by a processor, it can implement a method for calculating the saturation of a carbonate reservoir as described in Embodiment 1. Specifically, it performs the following steps:

[0098] Step 1: Obtain the neutron density curve, sonic curve, and core scanning photograph of the carbonate reservoir.

[0099] Step 2: Calculate the total porosity Φ of the carbonate reservoir based on the neutron and density curves, and calculate the sonic porosity Φ of the carbonate reservoir based on the sonic curve. nd curve. s

[0100] Step 3: Draw the non-connected porosity POR curve according to the total porosity Φ curve and the sonic porosity Φ curve. nd curve and the sonic porosity Φ s curve. non

[0101] Step 4: Perform first preprocessing and second preprocessing on the core scanning photograph to obtain a first result curve and a second result curve respectively.

[0102] Step 5: Establish the water saturation S of the oil reservoir lithofacies according to the non-connected porosity POR curve. non curve. w

[0103] Step 6: Construct a simplified volume model of the pore space fluid combination of the carbonate reservoir, and calculate the true water saturation S of the carbonate reservoir by combining the first result curve, the second result curve, and the water saturation S of the oil reservoir lithofacies. w curve. w_R

[0104] Embodiment 4

[0105] This embodiment provides the following example: There is a high-porosity and low-permeability carbonate reservoir in the central region of Iraq. The reservoir contains almost no shale components. There is no obvious difference in the porosity between the oil layer and the dry layer (tested without producing oil or water), and it is generally between 18% and 25%. However, the permeability difference between the oil layer and the dry layer is relatively large. The oil layer is usually between 2 and 20 mD, and the dry layer is usually less than 2 mD. In actual production, the oil layer and the dry layer are mainly identified by resistivity. The resistivity of the oil layer is generally greater than 2.0 Ω·m, and the resistivity of the dry layer is generally less than 1.0 Ω·m. As shown in Figure 2 , a resistivity of 1.0 - 2.0 Ω·m is generally interpreted as a poor oil layer. During the rolling exploration and development process, a special type of low-resistivity oil layer was discovered. The gas logging shows good results, the core is saturated with oil, and the core test results are consistent with those of the oil layer, but the resistivity is only 0.6 - 1 Ω·m, as shown in Figure 3 .​​​​

[0106] In this study area, there are two main reasons why reservoirs with porosity ranging from 18% to 25% and relatively low resistivity are interpreted as dry layers: Firstly, tests have confirmed that after acidification of such reservoirs, the liquid production capacity of the reservoirs is extremely low; Secondly, through core experiments, it has been found that the throat radius of such reservoirs is very small (such as Figure 4 the first one from the right in the middle), resulting in low permeability. Therefore, the origin of high-porosity dry layers can be summarized as follows: Poor connectivity between porosities causes oil and gas to be unable to displace formation water during the hydrocarbon accumulation process, preventing the formation of oil layers; Similarly, due to poor pore connectivity, the reservoir permeability is low, and it is also difficult for formation water to flow out of the formation, thus forming high-porosity dry layers.

[0107] Through core observation, it has been found that the cores of low-resistivity oil layers are generally brown, showing an oil-saturated characteristic, but there are also many white patches (such as Figure 2 in the middle, the right part is under sunlight and the left part is under fluorescence). These white patches belong to the lithofacies of dry layers. Since the formation water has not been displaced, the water saturation in the white patch area is close to 100%. The resistivity of the white patch area and the resistance of the brown oil-saturated area together determine the resistivity of the reservoir, thus forming a low-resistivity reservoir.

[0108] Assume the non-connected porosity as an isolated pore network model, that is, the total porosity is composed of one isolated pore space after another ( Figure 5 ). For this hypothetical model, neutron porosity and density porosity logging can detect the total porosity of the reservoir, while acoustic logging cannot measure the porosity. Therefore, we use the intersection of neutron and density curves to calculate Φ nd , and use the acoustic curve to calculate the porosity Φ s using the Wyllie formula. Φ nd - Φ s represents the non-connected porosity POR non . For well sections where the non-connected porosity is less than 0, the non-connected porosity is forced to be 0;

[0109] Identify the area of the non-connected porosity part in the core scan image. As shown in Figure 6 , obtain the white patch area S dry and the brown part area S oil ; and use N to represent the ratio of S dry to the total core area, and perform a 9-point filtering process; M = 1 - N. An example of calculating the N value is shown in the third one from the right in the middle of Figure 7 .

[0110] From the calculation results, it can be seen that there is a strong correlation between the N value and POR non . Taking the non-connected porosity POR non of the cored well as the abscissa and N as the ordinate, establish a crossplot, and regress the N value prediction relationship based on the oil-bearing identification results of the cored well core (Figure 7 (left part).

[0111] Based on the above analysis results of the causes of low-resistivity oil layers: the dry layer lithofacies are distributed in patches in the oil layer lithofacies. In this embodiment, the reservoir conductivity model is simplified to a parallel conductivity model of dry layer and oil layer, as Figure 8 shown, R oil The calculation results are shown in Figure 9 the fourth trace from the left in the figure.

[0112] R oil is used to replace the deep investigation resistivity curve R t in Archie's formula, and the water saturation S w of the oil layer lithofacies is obtained. Then, a simplified volume model of the pore space fluid combination is constructed: the pore space is filled with three kinds of fluids. The first part is the pores of the dry layer, which are all filled with formation water; the second part is the pores of the oil layer, which are filled with oil, gas and formation water. According to this model, the reservoir water saturation S w is obtained by using the above calculation results of S w_R 、N and M; The calculation results are shown in Figure 9 the third trace from the right in the figure. It can be seen that S w_R significantly decreases in the low-resistivity well section. As Figure 9 shown, the green dot curve in the third trace from the right in the figure is the chloroform bitumen A content extracted from the core. The reservoir water saturation calculated by this method is significantly more matched with it. It shows that the saturation calculated by this method can better reflect the real situation of the reservoir.

[0113] The specific embodiments described above have further detailed the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for calculating the saturation of a carbonate rock reservoir, characterized in that Including: Obtaining the neutron density curve, acoustic wave curve and core sweep photograph of a carbonate reservoir; Calculation of total porosity Φ of carbonate reservoirs based on neutron and density curves nd Curve, based on the acoustic wave curve to calculate the sonic porosity Φ of carbonate reservoirs s curve; According to the total porosity Φ nd curve and the acoustic porosity Φ s curve, the non-connected porosity POR non curve is plotted; Performing a first preprocessing and a second preprocessing on the core sweep photograph to obtain a first result curve and a second result curve respectively; Based on the non-connected porosity POR non establish the water saturation S of the reservoir lithofacies according to the curve w ; Construct a simplified volume model of the pore space fluid combination in carbonate reservoirs, and combine the first result curve, the second result curve and the water saturation S of the reservoir lithofacies w Calculate the true water saturation S of carbonate reservoirs w_R .

2. The saturation calculation method for a carbonate reservoir according to claim 1, characterized in that The non-connected porosity POR non The method for plotting the curve includes: According to formula Φ nd -Φ s Plot the non-connected porosity POR non curve. When Φ nd <Φ s occurs, set the non-connected porosity POR non = 0.

3. The saturation calculation method for a carbonate reservoir according to claim 1, wherein The performing a first preprocessing and a second preprocessing on the core sweep photograph to obtain a first result curve and a second result curve respectively includes: Method: Performing a binary scanning process on the core sweep photograph to identify the dry layer lithofacies area and the oil layer lithofacies area; Performing a filtering process on the curve of the ratio of the dry layer lithofacies area to the total core area to obtain a first result curve, and performing a filtering process on the curve of the ratio of the oil layer lithofacies area to the total core area to obtain a second result curve.

4. The saturation calculation method for a carbonate reservoir according to claim 3, wherein The oil reservoir lithofacies water saturation S non is established according to the curve of non-connected porosity POR w ; including Method: Establishing a parallel conductive model based on the dry layer lithofacies and the oil layer lithofacies: Where: R oil represents the resistivity of the oil-bearing layer part; R dry represents the resistivity of the dry layer part; R t represents the resistivity of the deep investigation in logging; M represents the ratio of the oil-bearing facies area to the total core area; N represents the ratio of the dry layer facies area to the total core area; The water saturation S of the oil reservoir lithofacies is derived according to the parallel conduction model and Archie's formula w .

5. The saturation calculation method for a carbonate reservoir according to claim 4, characterized in that, In the process of deriving the water saturation S of the reservoir lithofacies based on the parallel conductivity model and Archie's formula w : If R appears oil <R t , or R dry ≤N·R t then R is forced oil =R t ; If R appears oil > 4R t , then force R oil = 4R t .

6. The saturation calculation method for a carbonate reservoir according to claim 5, characterized in that The water saturation S of the reservoir lithofacies w is as follows: where R w represents the resistivity of formation water; Φ represents the total porosity calculated from the three porosity curves, a and m represent the cementation exponent; b and n represent the saturation exponent.

7. The saturation calculation method for a carbonate rock reservoir according to claim 1, characterized in that The pore space fluid combination simplified volume model includes a dry layer pore part and an oil layer pore part; all of the dry layer pore part is filled with formation water, and the oil layer pore part is filled with oil and gas and formation water.

8. A method for calculating the saturation of a carbonate reservoir according to claim 6, characterized in that, Combining the first achievement curve, the second achievement curve, and the water saturation S of the reservoir lithofacies w calculate the true water saturation S of the carbonate reservoir w_R ; including Method: Calculate the formation water saturation of the simplified volume model of pore space fluid combination based on the following formula as the true water saturation S of carbonate reservoirs w_R : When S w_R > S w , then force S w_R = S w .

9. A saturation calculation system for carbonate rock reservoirs, characterized in that, For implementing the carbonate reservoir saturation calculation method based on resistivity correction according to any one of claims 1-8; the system includes: An acquisition module, configured to obtain the neutron density curve, acoustic wave curve and core sweep photograph of a carbonate reservoir; The first calculation module is used to calculate the total porosity Φ of the carbonate reservoir based on neutron and density curves nd Curve, calculate the acoustic porosity Φ of the carbonate reservoir based on the acoustic curve s Curve; A drawing module, for drawing a non-connected porosity POR nd curve according to a total porosity Φ s curve and an acoustic porosity Φ non curve; A preprocessing module, configured to perform a first preprocessing and a second preprocessing on the core sweep photograph to obtain a first result curve and a second result curve respectively; A building module, which is used to establish the water saturation S of the reservoir lithofacies according to the non-connected porosity POR non curve w ; The second calculation module is used to construct a simplified volume model of the pore space fluid combination of the carbonate reservoir, and combine the first result curve, the second result curve and the water saturation S of the oil reservoir lithofacies w to calculate the true water saturation S of the carbonate reservoir w_R .

10. A computer-readable medium having a computer program stored thereon, characterized in that, The computer program, when executed by a processor, can implement a saturation calculation method for a carbonate reservoir according to any one of claims 1-8.

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