阅读说明：本技术 可动水饱和度的评价方法、装置、电子设备及介质 (Method and device for evaluating movable water saturation, electronic device, and medium ) 是由 申本科 张生根 于 2020-05-20 设计创作，主要内容包括：本发明公开了可动水饱和度的评价方法、装置、电子设备及介质,该方法包括：获取地层径向电阻率；对阿尔奇公式进行径向微分；基于径向微分的阿尔奇公式和地层径向电阻率,获取地层含水饱和度的微分值；基于地层含水饱和度的微分值,获取可动水饱和度。本发明基于电阻率径向微分法求含水饱和度消除了地层水矿化度、泥质含量、混合液地层水电阻率等因素的影响,避开了储层孔隙度的求取,更为准确的反映了储层地质参数变化的综合响应,有效的减少了物性参数计算带来的误差和岩性带来的影响,提高了含水饱和度计算的精度,同时具有良好的可操作性和实用性。(The invention discloses a method and a device for evaluating movable water saturation, electronic equipment and a medium, wherein the method comprises the following steps: acquiring the formation radial resistivity; carrying out radial differentiation on the Archie formula; acquiring a differential value of the stratum water saturation based on an Archie's formula of radial differential and the stratum radial resistivity; and acquiring the movable water saturation based on the differential value of the stratum water saturation. The method solves the water saturation based on the resistivity radial differential method, eliminates the influence of factors such as the formation water mineralization, the argillaceous content, the mixed liquid formation water resistivity and the like, avoids the solving of the reservoir porosity, more accurately reflects the comprehensive response of the reservoir geological parameter change, effectively reduces the error brought by the physical property parameter calculation and the influence brought by the lithology, improves the accuracy of the water saturation calculation, and has good operability and practicability.)

1. A method for evaluating movable water saturation, comprising:

acquiring the formation radial resistivity;

carrying out radial differentiation on the Archie formula;

acquiring a differential value of the stratum water saturation based on an Archie's formula of radial differential and the stratum radial resistivity;

and acquiring the movable water saturation based on the differential value of the stratum water saturation.

2. The method of assessing movable water saturation according to claim 1, wherein said Archie's formula is:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

3. The method of assessing mobile water saturation according to claim 2, wherein the differential values of formation water saturation are:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

4. The method of assessing movable water saturation according to claim 3, wherein said movable water saturation is obtained using the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of water saturation between the zone of washout and the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

5. The method of assessing mobile water saturation according to claim 4, wherein the formation radial resistivity is obtained using an array induction logging tool.

6. The method of assessing movable water saturation according to claim 5, wherein radial probe depths of said array induction tool are l0 inches, 20 inches, 30 inches, 60 inches, 90 inches and 120 inches.

7. The method of assessing movable water saturation according to claim 6, wherein dS_w1A radial variation value of water saturation, dS, calculated for resistivity acquired at a radial probe depth of 60 inches for the array induction tool_w2A radial variation value of water saturation calculated for resistivity acquired based on a radial probe depth of the array induction tool of 90 inches.

8. An electronic device, characterized in that the electronic device comprises:

a memory storing executable instructions;

a processor executing the executable instructions in the memory to implement the method of assessing movable water saturation according to any one of claims 1-7.

9. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program which, when being executed by a processor, carries out the method of assessing movable water saturation according to any one of claims 1-7.

10. An apparatus for evaluating movable water saturation, comprising:

the first acquisition module is used for acquiring the formation radial resistivity;

the differential module is used for carrying out radial differential on the Archie formula;

the second acquisition module is used for acquiring a differential value of the stratum water saturation based on the radial differential Archie formula and the stratum radial resistivity;

and the third acquisition module acquires the movable water saturation based on the differential value of the stratum water saturation.

Technical Field

The invention belongs to geophysical exploration, and particularly relates to a method and a device for evaluating movable water saturation, electronic equipment and a medium.

Background

In well logging technology, reservoir water saturation is an important parameter for evaluating reservoir fluid and reserve calculation, and is also the core of quantitative evaluation of oil and gas reservoirs. Resistivity-based saturation evaluation is most commonly used in current logging techniques, although other logging techniques can also provide information about reservoir saturation. Mr. Archie in 1941 announced a famous paper about determining reservoir parameters by resistivity logging in the daras oil-and-mining society, and formally published Archie (Archie) formula with epoch-making significance for electrical logging in 1942, which lays the theoretical foundation for explaining the saturation of oil-gas layers by logging.

With the deepening of reservoir saturation research, saturation evaluation parameters are obtained by correcting the Archie theory. Currently, the ways of correcting the Archie theory fall into two categories: firstly, on the basis of rock-electricity experiments or numerical simulation calculation, a cementation index m and a saturation index n are properly adjusted, and then the oil-gas saturation is determined by applying an Archie formula, such as a method for calculating an m value by a pennisetum (2006) three-porosity model; and lie (2003) employs an empirical estimation m, n exponential method in complex reservoir well log interpretation studies. Secondly, on the microscopic level of the reservoir layer, a new saturation equation is deduced according to the multiple pore medium parallel connection conduction rule and the Archie theory, such as the saturation equations of various pore network models of Crane (1990) and the saturation model of Lining (1989), and the models and equations are applied to different regions to a certain extent.

Over 60 years, researchers have provided a plurality of extended oil and gas saturation explanation models based on Archie (Archie) formula and on the basis of experiments and theoretical research, and the difference between the obtained results is large due to the influence of factors such as rock physical properties, pore structure and mud quality, for example, the difference between the Indonesian model and the Archie model is as high as 20%.

In short, from the current technical level, no unified high-precision saturation evaluation method with strong operability is formed for the logging saturation evaluation.

Disclosure of Invention

The invention aims to provide a method for evaluating the movable water saturation, which solves the problem that no unified saturation evaluation method with strong operability and high precision is formed at present.

In view of the above, the present invention provides a method, an apparatus, an electronic device, and a medium for evaluating movable water saturation, which at least solve the problem that a uniform saturation evaluation method with high operability and high accuracy is not formed at present.

In a first aspect, the present invention provides a method for evaluating movable water saturation, comprising: acquiring the formation radial resistivity; carrying out radial differentiation on the Archie formula; acquiring a differential value of the stratum water saturation based on an Archie's formula of radial differential and the stratum radial resistivity; and acquiring the movable water saturation based on the differential value of the stratum water saturation.

Optionally, the algic formula is:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

Optionally, the differential value of the formation water saturation is:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is lithology dependentB is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

Optionally, the movable water saturation is obtained by using the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

Optionally, an array induction logging tool is used to obtain the formation radial resistivity.

Optionally, the array induction tool has radial probe depths of l0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches.

Optionally, dS_w1A radial variation value of water saturation, dS, calculated for resistivity acquired at a radial probe depth of 60 inches for the array induction tool_w2A radial variation value of water saturation calculated for resistivity acquired based on a radial probe depth of the array induction tool of 90 inches.

In a second aspect, the present invention also provides an electronic device, including: a memory storing executable instructions; a processor executing the executable instructions in the memory to implement the method for assessing movable water saturation described above.

In a third aspect, the present invention also provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described method for evaluating movable water saturation.

In a fourth aspect, the present invention also provides a movable water saturation evaluation device, including: the first acquisition module is used for acquiring the formation radial resistivity; the differential module is used for carrying out radial differential on the Archie formula; the second acquisition module is used for acquiring a differential value of the stratum water saturation based on the radial differential Archie formula and the stratum radial resistivity; and the third acquisition module acquires the movable water saturation based on the differential value of the stratum water saturation.

Optionally, the algic formula is:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

Optionally, the differential value of the formation water saturation is:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is a holeGap, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

Optionally, the movable water saturation is obtained by using the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

Optionally, an array induction logging tool is used to obtain the formation radial resistivity.

Optionally, the array induction tool has radial probe depths of l0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches.

Optionally, dS_w1A radial variation value of water saturation, dS, calculated for resistivity acquired at a radial probe depth of 60 inches for the array induction tool_w2A radial variation value of water saturation calculated for resistivity acquired based on a radial probe depth of the array induction tool of 90 inches.

The invention has the beneficial effects that: the evaluation method of movable water saturation of the invention carries out radial differentiation on the Archie formula, combines the resistivity of radial change to calculate the differential value of stratum water saturation, further calculates the movable water saturation, calculates the water saturation based on the resistivity radial differentiation method, eliminates the influence of factors such as stratum water mineralization, argillaceous content, mixed liquid stratum water resistivity and the like because the response characteristic of the array induction logging in an oil-water layer and mud invasion is fully considered, avoids the calculation of the reservoir porosity, more accurately reflects the comprehensive response of the reservoir geological parameter change compared with the calculation of the movable water saturation by directly utilizing the Archie formula, effectively reduces the influence brought by the physical property parameter calculation and the influence brought by lithology, improves the calculation precision of the water saturation, simultaneously has good theoretical operability and practicability, and has good theoretical foundation and experimental foundation, the situation that the calculation result is simulated according to experience or complex numerical values when the Archie theory is corrected at present is changed.

The present invention has other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.

FIG. 1 shows a flow diagram of a method for assessing movable water saturation according to one embodiment of the present invention.

Fig. 2 shows a diagram of the well logging interpretation result of S2 in a certain oil field in the east of china.

Fig. 3 shows a block diagram of a device for assessing movable water saturation according to an embodiment of the present invention.

102. A first acquisition module; 104. a differential module; 106. a second acquisition module; 108. and a third obtaining module.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.

The invention provides a method for evaluating movable water saturation, which comprises the following steps: acquiring the formation radial resistivity; carrying out radial differentiation on the Archie formula; acquiring a differential value of the stratum water saturation based on an Archie's formula of radial differential and the stratum radial resistivity; and acquiring the movable water saturation based on the differential value of the stratum water saturation.

In the high water content exploitation stage, in order to economically and effectively improve the recovery efficiency, the residual oil and the saturation thereof are taken as main targets, refined, quantified, dynamic and predicted reservoir descriptions are carried out, the free fluid saturation and the distribution thereof are solved, the free fluid saturation is combined with the comprehensive water content and water content of oil extraction, the water flooded layer is quantitatively explained, the clear water flooded level is determined, and the movable water saturation is used for quantitatively explaining the weak water flooded layer, the medium water flooded layer and the strong water flooded layer.

According to the reservoir oil and water saturation and definition thereof

S_w+S_o＝1 (1)

S_wi+S_om+S_or＝1 (2)

Wherein S is_wAs the water saturation of the formation, S_oIs the oil saturation of the formation, S_wiTo restrict water saturation, S_omTo movable oil saturation, S_orResidual oil saturation.

After a period of exploitation, water injection is needed for exploitation, movable water exists in the stratum, and for the oil layer flooded by the water injection, the movable water exists

S_wi+S_om+S_or+S_wf＝1 (3)

Wherein S is_wiTo restrict water saturation, S_omTo movable oil saturation, S_orAs residual oil saturation, S_wfIs the mobile water saturation.

In the radial direction, the equation (3) is differentiated

dS_wi+dS_om+dS_or+dS_wf＝0 (4)

In contrast, S_wi、S_orIs a constant, dS_wi＝0，dS_orIs equal to 0, thus obtaining

dS_wf＝-dS_om (5)

Equation (5) indicates that the amount of change in the movable water should be equal to the amount of change in the movable oil displaced by the water, and the negative sign indicates that both displace each other. However, since the reservoir is depleted after a period of production, the reservoir begins to be filled with water, and therefore, it is the actual situation that the mobile water occupies the pore space for producing the mobile oil instead of the mobile oil at that time. Thus the mobile water saturation is actually greater than the mobile oil saturation, which is also the reason for the high integrated water cut during oil recovery, discussed above for the formation water saturation and oil saturation.

The invention calculates the stratum water saturation by carrying out radial differentiation on the Archie equation, if the Archie equation is required to be carried to the annulus from the flushing zone and then to the undisturbed stratum, the obtained differential value of the stratum water saturation is the differential value of the movable water saturation, namely

S_w＝S_wf+S_wi (6)

dS_w＝d(S_wf+S_wi)＝dS_wf (7)

Wherein S is_wAs the water saturation of the formation, S_wiTo restrict water saturation, S_wfIs the mobile water saturation.

Specifically, the resistivity reflecting the change of the stratum water saturation of different radial detection depths is obtained, radial differentiation is carried out on the Archie formula, and the differential value of the stratum water saturation is obtained through the formula obtained after radial differentiation of the Archie formula and the radial resistivity, so that the movable water saturation is obtained.

The method for solving the water saturation based on the resistivity radial differential method fully considers the response characteristics of the array induction logging in the invasion of an oil-water layer and mud, eliminates the influence of factors such as the salinity of formation water, the shale content, the resistivity of mixed liquid formation water and the like, avoids the solving of the porosity of a reservoir, more accurately reflects the comprehensive response of the change of geological parameters of the reservoir compared with the method for solving the movable water saturation of the reservoir by directly utilizing an Archie formula, has good operability and practicability, simultaneously has good theoretical basis and experimental basis, and changes the condition of simulating and calculating results according to experience or complex numerical values when the Archie theory is corrected at present.

In one example, reservoir fluid identification and quantitative evaluation of the waterflood level is achieved by further evaluating the waterflood level by comparing the movable water saturation to a threshold.

According to the exemplary embodiment, the evaluation method of the movable water saturation carries out radial differentiation on the Archie formula, combines the resistivity of radial change to calculate the differential value of the stratum water saturation, and further calculates the movable water saturation.

Alternatively, the Archie's formula is:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

Specifically, the Archie's formula for calculating the water saturation of the formation is as follows:

obtained by combining the formulas (8) and (9)

Wherein F is the formation factor, R₀Is the pure rock resistivity, R, of 100% water_wIs the formation water resistivity, a is the lithology constant associated with lithology,is the porosity, m is the cementation index, I is the resistivity increase, R_tIs the formation resistivity, b is a constant related to saturation, S_wIs the water saturation and n is the saturation index.

Alternatively, the differential value of the formation water saturation is:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

Specifically, the differential of the Archie's equation is obtained

The formation porosity being radially constant, i.e.Then

Wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

The mathematical meaning of radial differentiation of the Archie equation is the change in the water saturation function due to a change in the resistivity of the variables. From the geological perspective, the influence of the changes of the mineralization degree, the shale content and the formation water resistivity on the reservoir water saturation is eliminated after radial differentiation, and the change value dS of the formation radial water saturation is only caused by the change of the radial movable water saturation, so that the dS reflects the radial movable water saturation.

Alternatively, the movable water saturation is obtained using the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

Specifically, the movable water saturation is calculated by the following formula,

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

As an alternative, an array induction logging tool is used to obtain the formation radial resistivity.

Alternatively, the radial depths of investigation of the array induction tool are l0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches.

In particular, conventional well log data have a limited number of conductivity curves with different depths of investigation. Therefore, conventional log-based radial conductivity distribution inversion can only employ simple step-like invasion profile models. The radial invasion profile of the formation is believed to consist of two parts, the zone of washout and the undisturbed formation, lacking the transition zone from the washout zone to the undisturbed formation, also called the annulus: such models do not reflect true formation invasion well.

In the 90 s of the 20 th century, array induction logging tools were put into production. The array induction log can be measured simultaneously to obtain six resistivity curves at different depths of investigation, i 0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches. As the number of formation radial resistivity curves increases, it is possible to describe the surface area of the invasion profile model for the washzone, undisturbed formation and transition zone, 60 inches being able to detect the washzone and 90 inches being able to detect the undisturbed formation.

These resistivity curves reflect in more detail the changing characteristics of the reservoir fluid properties in the radial direction of the reservoir, while also providing resistivity data for calculating the reservoir water saturation and its distribution at different depths of investigation. As the number of formation radial resistivity curves increases, the invasion profile model of the washzone, undisturbed formation and transition zone from can be described as the operational surface. The resistivity at these different depths of investigation reflects the reservoir water saturation at the different depths of investigation, which provides a practical basis for the radial differentiation of the Archie's equation. Thus, the present invention employs an array induction tool to detect resistivity at radial depth.

Alternatively, dS_w1Radial variation value of water saturation, dS, calculated for resistivity acquired at radial probe depth of 60 inches based on array induction tool_w2A radial variation value of water saturation calculated for resistivity based on a radial probe depth of the array induction tool of 90 inches.

Specifically, in a permeable stratum, the detection depth of 10 inches of resistivity in the array induction logging instrument is 15-20 cm, the formation flushing zone is mainly detected, the detection depth of 60 inches of resistivity is about 1.5m, the formation flushing zone and the transition zone are mainly detected, the detection depth of 120 inches of resistivity logging can reach more than 3m, and the undisturbed stratum can be reflected.

The change in water saturation between the irrigation zone and the transition zone was calculated using a resistivity of 10 inches and a resistivity of 60 inches, and the change in water saturation between the irrigation zone and the undisturbed zone was calculated using a resistivity of 10 inches and a resistivity of 90 inches.

The present invention also provides an electronic device, comprising: a memory storing executable instructions; and the processor executes executable instructions in the memory to realize the movable water saturation evaluation method.

The present invention also provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described method for evaluating movable water saturation.

The invention also provides a device for evaluating the movable water saturation, which comprises: the first acquisition module is used for acquiring the formation radial resistivity; the differential module is used for carrying out radial differential on the Archie formula; the second acquisition module is used for acquiring a differential value of the stratum water saturation based on the radial differential Archie formula and the stratum radial resistivity; and the third acquisition module acquires the movable water saturation based on the differential value of the stratum water saturation.

The invention calculates the stratum water saturation by carrying out radial differentiation on the Archie equation, if the Archie equation is required to be carried to the annulus from the flushing zone and then to the undisturbed stratum, the obtained differential value of the stratum water saturation is the differential value of the movable water saturation, namely

S_w＝S_wf+S_wi (6)

dS_w＝d(S_wf+S_wi)＝dS_wf (7)

Wherein S is_wAs the water saturation of the formation, S_wiTo restrict water saturation, S_wfIs the mobile water saturation.

Specifically, the resistivity reflecting the change of the reservoir water saturation at different radial detection depths is obtained, radial differentiation is carried out on the Archie formula, and the differential value of the stratum water saturation is obtained through the formula after radial differentiation of the Archie formula and the radial resistivity, so that the movable water saturation is obtained.

The method for solving the water saturation based on the resistivity radial differential method fully considers the response characteristics of the array induction logging in the invasion of an oil-water layer and mud, eliminates the influence of factors such as the salinity of formation water, the shale content, the resistivity of mixed liquid formation water and the like, avoids the solving of the porosity of a reservoir, more accurately reflects the comprehensive response of the change of geological parameters of the reservoir compared with the method for solving the movable water saturation of the reservoir by directly utilizing an Archie formula, has good operability and practicability, simultaneously has good theoretical basis and experimental basis, and changes the condition of simulating and calculating results according to experience or complex numerical values when the Archie theory is corrected at present.

In one example, reservoir fluid identification and quantitative evaluation of the waterflood level is achieved by further evaluating the waterflood level by comparing the movable water saturation to a threshold.

According to an exemplary embodiment, the evaluation device of the movable water saturation carries out radial differentiation on the Archie formula, combines the resistivity of radial change to calculate the differential value of the stratum water saturation, and further calculates the movable water saturation.

Alternatively, the Archie's formula is:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

Specifically, the Archie's formula for calculating the water saturation of the formation is as follows:

obtained by combining the formulas (8) and (9)

Wherein F is the formation factor, R₀Is the pure rock resistivity, R, of 100% water_wIs the formation water resistivity, a is the lithology coefficient associated with lithology,is the porosity, m is the cementation index, I is the resistivity increase, R_tIs the formation resistivity, b is a constant related to saturation, S_wIs the water saturation and n is the saturation index.

Alternatively, the differential value of the formation water saturation is:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

Specifically, the differential of the Archie's equation is obtained

The formation porosity being radially constant, i.e.Then

Wherein dS_wIs the radial variation value of the water saturation, i.e. the groundDifferential value of the saturation of the layer water, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

The mathematical meaning of radial differentiation of the Archie equation is the change in the water saturation function due to a change in the resistivity of the variables. From the geological perspective, the influence of the changes of the mineralization degree, the shale content and the formation water resistivity on the reservoir water saturation is eliminated after radial differentiation, and the change value dS of the formation radial water saturation is only caused by the change of the radial movable water saturation, so that the dS reflects the radial movable water saturation.

Alternatively, the movable water saturation is obtained using the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

Specifically, the movable water saturation is calculated by the following formula,

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

As an alternative, an array induction logging tool is used to obtain the formation radial resistivity.

Alternatively, the radial depths of investigation of the array induction tool are l0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches.

In particular, conventional well log data have a limited number of conductivity curves with different depths of investigation. Therefore, conventional log-based radial conductivity distribution inversion can only employ simple step-like invasion profile models. The radial invasion profile of the formation is believed to consist of two parts, the zone of washout and the undisturbed formation, lacking the transition zone from the washout zone to the undisturbed formation, also called the annulus: such models do not reflect true formation invasion well.

In the 90 s of the 20 th century, array induction logging tools were put into production. The array induction log can be measured simultaneously to obtain six resistivity curves at different depths of investigation, i 0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches. As the number of formation radial resistivity curves increases, it is possible to describe the surface area of the invasion profile model for the washzone, undisturbed formation and transition zone, 60 inches being able to detect the washzone and 90 inches being able to detect the undisturbed formation.

These resistivity curves reflect in more detail the changing characteristics of the reservoir fluid properties in the radial direction of the reservoir, while also providing resistivity data for calculating the reservoir water saturation and its distribution at different depths of investigation. As the number of formation radial resistivity curves increases, the invasion profile model of the washzone, undisturbed formation and transition zone from can be described as the operational surface. The resistivity at these different depths of investigation reflects the reservoir water saturation at the different depths of investigation, which provides a practical basis for the radial differentiation of the Archie's equation. Thus, the present invention employs an array induction tool to detect resistivity at radial depth.

Alternatively, dS_w1Radial variation value of water saturation, dS, calculated for resistivity acquired at radial probe depth of 60 inches based on array induction tool_w2A radial variation value of water saturation calculated for resistivity based on a radial probe depth of the array induction tool of 90 inches.

Specifically, in a permeable stratum, the detection depth of 10 inches of resistivity in the array induction logging instrument is 15-20 cm, the formation flushing zone is mainly detected, the detection depth of 60 inches of resistivity is about 1.5m, the formation flushing zone and the transition zone are mainly detected, the detection depth of 120 inches of resistivity logging can reach more than 3m, and the undisturbed stratum can be reflected.

The change in water saturation between the irrigation zone and the transition zone was calculated using a resistivity of 10 inches and a resistivity of 60 inches, and the change in water saturation between the irrigation zone and the undisturbed zone was calculated using a resistivity of 10 inches and a resistivity of 90 inches.

Example one

FIG. 1 shows a flow diagram of a method for assessing movable water saturation according to one embodiment of the present invention. Fig. 2 shows a diagram of the well logging interpretation result of S2 in a certain oil field in the east of china.

As shown in fig. 1, the method for evaluating the movable water saturation includes:

step 1: acquiring the formation radial resistivity;

the method comprises the following steps of obtaining the formation radial resistivity by using an array induction logging instrument.

Wherein the radial depths of investigation of the array induction tool are l0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches.

Step 2: carrying out radial differentiation on the Archie formula;

wherein, the Archie formula is as follows:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

Specifically, the Archie's formula for calculating the water saturation of the formation is as follows:

obtained by combining the formulas (8) and (9)

Wherein F is the formation factor, R₀Is the pure rock resistivity, R, of 100% water_wIs the formation water resistivity, a is the lithology coefficient associated with lithology,is the porosity, m is the cementation index, I is the resistivity increase, R_tIs the formation resistivity, b is a constant related to saturation, S_wIs the water saturation and n is the saturation index.

And step 3: acquiring a differential value of the stratum water saturation based on an Archie's formula of radial differential and the stratum radial resistivity;

wherein the differential value of the formation water saturation is:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

Specifically, the differential of the Archie's equation is obtained

The formation porosity being radially constant, i.e.Then

Wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

And 4, step 4: and acquiring the movable water saturation based on the differential value of the stratum water saturation.

Wherein the movable water saturation is obtained by adopting the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

Wherein dS_w1Radial variation value of water saturation, dS, calculated for resistivity acquired at radial probe depth of 60 inches based on array induction tool_w2A radial variation value of water saturation calculated for resistivity based on a radial probe depth of the array induction tool of 90 inches.

In order to illustrate the evaluation effect and the adaptability of the oil-gas saturation in the reservoir, the method respectively calculates the actual logging information from the east sandstone reservoir of China and compares the actual logging information with the nuclear magnetic resonance logging analysis result to check the effectiveness and the adaptability of the method.

FIG. 2 is a diagram of the well logging results of S2 well in certain oil field of eastern China, and the main analysis well section is 725-745 m. The stratum at the section is formed by the interaction of sandstone and mudstone with different thicknesses, the amplitude of natural potential reflects the obvious change of physical property difference, the interface is clear, the interval containing gas presents the characteristics of medium resistance and high resistance, the resistivity is 10-300 omega-m, and the nuclear magnetic resonance T2 spectrum and the total porosity, the movable fluid porosity, the natural potential and the resistivity obtained by calculation have good correspondence.

From the figure, it can be seen that the water saturation calculated by the radial resistivity differential method is 30% in the section 725-730 m, that is, the gas saturation is 70%, and the reservoir is a gas layer; 730-731 m, the water saturation calculated by radial resistivity differential method is 40%, the oil saturation is 30%, the gas saturation is 30%, it is strong water flooded layer; the water saturation calculated by radial resistivity differential method of sections 734-736 m and sections 736.4-742.2 m is 0, and the oil saturation is 42% and 51%, although the calculated gas saturation is not very high, no movable water saturation exists, the gas layer is determined, the oil layer is tested in 6 months in 2013, the daily gas production is 2.6 ten thousand square, and no water is produced; sections 734-736 m and sections 736.4-742.2 m are low gas barrier layers.

Five large-diameter water-washing coring inspection wells in HN oil fields of eastern China are explained according to the standard quantitative treatment, and the calculation results are shown in Table 1.

The calculation result shows that:

(1) the water saturation calculated by the Archie equation is not consistent with the oil testing conclusion no matter in a strong water flooded layer, a medium water flooded layer or a weak water flooded layer, so that the water saturation calculated by the resistivity radial differential method has better consistency with the result of quantitative interpretation according to the water flooded layer judgment standard and the oil testing conclusion.

(2) After the verification of the 19 layers of 8 typical flooded wells, the interpretation result of the method is in accordance with 17 layers and not in accordance with 2 layers.

TABLE 1 comparison table of well logging interpretation conclusion and oil testing conclusion parameters of water washing inspection well

Example two

Fig. 3 shows a block diagram of a device for assessing movable water saturation according to an embodiment of the present invention.

As shown in fig. 3, the movable water saturation evaluating apparatus includes:

a first obtaining module 102, for obtaining the formation radial resistivity;

the method comprises the following steps of obtaining the formation radial resistivity by using an array induction logging instrument.

Wherein the radial depths of investigation of the array induction tool are l0 inches, 20 inches, 30 inches, 60 inches, 90 inches, and 120 inches.

A differential module 104 for performing radial differentiation on the Archie's equation;

wherein, the Archie formula is as follows:

wherein S is_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the formation water resistivity, R_tIs the resistivity of the earth formation,is the porosity and m is the cementation index.

Specifically, the Archie's formula for calculating the water saturation of the formation is as follows:

obtained by combining the formulas (8) and (9)

Wherein F is the formation factor, R₀Is the pure rock resistivity, R, of 100% water_wIs the formation water resistivity, a is the lithology coefficient associated with lithology,is the porosity, m is the cementation index, I is the resistivity increase, R_tIs the formation resistivity, b is a constant related to saturation, S_wIs the water saturation and n is the saturation index.

The second acquisition module 106 is used for acquiring a differential value of the stratum water saturation based on the Archie's formula of radial differential and the stratum radial resistivity;

wherein the differential value of the formation water saturation is:

wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

Specifically, the differential of the Archie's equation is obtained

The formation porosity being radially constant, i.e.Then

Wherein dS_wIs the radial variation value of the water saturation, i.e. the differential value of the formation water saturation, S_wIs the water saturation, n is the saturation index, a is the lithology coefficient related to lithology, b is a constant related to saturation, R_wIs the resistivity of the formation water,is the porosity, m is the cementation index, R_tIs the formation resistivity, dR_wIs the radial variation value of the resistivity of the reservoir fluid, dR_tIs the radial variation value of the reservoir resistivity.

And the third acquisition module 108 acquires the movable water saturation based on the differential value of the stratum water saturation.

Wherein the movable water saturation is obtained by adopting the following formula:

wherein S is_wfFor movable water saturation, dS ═ dS_w1-dS_w2dS is the change in the radial water saturation of the formation, dS_w1Is the radial variation value of the water saturation between the irrigation zone and the annulus, dS_w2Is the radial variation value of the water saturation of the washout zone to the undisturbed formation, dS₀Is the change in saturation of a 100% water-bearing formation and n' is the saturation index.

Wherein dS_w1Radial variation value of water saturation, dS, calculated for resistivity acquired at radial probe depth of 60 inches based on array induction tool_w2A radial variation value of water saturation calculated for resistivity based on a radial probe depth of the array induction tool of 90 inches.

EXAMPLE III

The present disclosure provides an electronic device including: a memory storing executable instructions; and the processor executes executable instructions in the memory to realize the movable water saturation evaluation method.

An electronic device according to an embodiment of the present disclosure includes a memory and a processor.

The memory is to store non-transitory computer readable instructions. In particular, the memory may include one or more computer program products that may include various forms of computer-readable storage media, such as volatile memory and/or non-volatile memory. The volatile memory may include, for example, Random Access Memory (RAM), cache memory (cache), and/or the like. The non-volatile memory may include, for example, Read Only Memory (ROM), hard disk, flash memory, etc.

The processor may be a Central Processing Unit (CPU) or other form of processing unit having data processing capabilities and/or instruction execution capabilities, and may control other components in the electronic device to perform desired functions. In one embodiment of the disclosure, the processor is configured to execute the computer readable instructions stored in the memory.

Those skilled in the art should understand that, in order to solve the technical problem of how to obtain a good user experience, the present embodiment may also include well-known structures such as a communication bus, an interface, and the like, and these well-known structures should also be included in the protection scope of the present disclosure.

For the detailed description of the present embodiment, reference may be made to the corresponding descriptions in the foregoing embodiments, which are not repeated herein.

Example four

The present disclosure provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described method of evaluating movable water saturation.

A computer-readable storage medium according to an embodiment of the present disclosure has non-transitory computer-readable instructions stored thereon. The non-transitory computer readable instructions, when executed by a processor, perform all or a portion of the steps of the methods of the embodiments of the disclosure previously described.

The computer-readable storage media include, but are not limited to: optical storage media (e.g., CD-ROMs and DVDs), magneto-optical storage media (e.g., MOs), magnetic storage media (e.g., magnetic tapes or removable disks), media with built-in rewritable non-volatile memory (e.g., memory cards), and media with built-in ROMs (e.g., ROM cartridges).

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.