A method and device for determining rock saturation index of oil-wet reservoir

Abstract

This article provides a method and device for determining the saturation index of oil-wet reservoir rocks, wherein the method includes: obtaining a core of the reservoir to be tested, measuring the first porosity of the core before washing oil and salt, and the first curve of resistivity changing with water saturation; measuring the second porosity and fully saturated solution resistivity of the core after washing oil and salt; calculating the resistivity increase rate of the core according to the fully saturated solution resistivity; correcting the water saturation of the core according to the first porosity, the second porosity and the first curve; calculating the saturation index of the core before washing oil and salt according to the resistivity increase rate and the corrected water saturation. The method provided in this article obtains a relatively accurate resistivity increase rate and water saturation of the core, and then calculates the saturation index of the core under the original wettability conditions, thereby solving the problem of the difficulty in determining the saturation index of oil-wet rocks in the prior art, and providing a scientific basis for reservoir development research.

Description

Technical Field

[0001] The present invention relates to the field of geological exploration technology, and in particular to a method and device for determining the rock saturation index of an oil-wet reservoir. Background Art

[0002] Saturation evaluation is the core of quantitative evaluation of oil and gas reservoirs, and the value of the saturation index has a great influence on the accuracy of saturation calculation. The saturation index is usually not fixed, but will change with changes in factors such as temperature, pressure, and pore structure. In addition, the wettability of rock is also an important factor affecting the saturation index. The wettability of reservoir rock affects the distribution of fluid in the pore throat, and thus affects the size of the saturation index. In the prior art, the experimental method of "aging" is often used to eliminate the influence of reservoir rock wettability on coring and core washing of oil and salt, but the recovery effect of "aging" on reservoir rock wettability is poor during the experiment. Therefore, the solution in the prior art cannot effectively eliminate the influence of the change in wettability caused by oil and salt washing after coring, and thus cannot accurately determine the saturation index of the rock.

[0003] In view of this, this paper aims to provide a method and device for determining the rock saturation index of oil-wet reservoirs. Summary of the invention

[0004] In view of the above problems in the prior art, the purpose of this article is to provide a method and device for determining the rock saturation index of an oil-wet reservoir, so as to solve the problem that it is difficult to accurately obtain the reservoir saturation index in the prior art.

[0005] In order to solve the above technical problems, the specific technical solutions of this article are as follows:

[0006] In a first aspect, the present invention provides a method for determining a rock saturation index of an oil-wet reservoir, comprising:

[0007] Obtaining the reservoir core to be tested;

[0008] Determine a first porosity of the core before washing oil and salt and a first curve of resistivity changing with water saturation;

[0009] Determining the second porosity and fully saturated solution resistivity of the core after washing oil and salt;

[0010] Calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution;

[0011] Correcting the water saturation of the core according to the first porosity, the second porosity and the first curve;

[0012] The saturation index of the core before oil and salt washing is calculated based on the resistivity increase rate and the corrected water saturation.

[0013] Specifically, calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution includes:

[0014] Determining the oil resistivity of the core before washing oil and salt;

[0015] The resistivity increase rate of the core is calculated based on the resistivity of the fully saturated solution and the resistivity of the oil content.

[0016] Furthermore, the resistance increase rate of the core is calculated by the following formula:

[0017]

[0018] Among them, I Ar is the resistivity increase rate of the core; R tA represents the oil resistivity of the core before washing oil and salt; R oB It represents the resistivity of the fully saturated solution of the core after washing oil and salt.

[0019] Further, correcting the water saturation of the core according to the first porosity, the second porosity and the first curve further includes:

[0020] The water saturation of the core was corrected by the following formula:

[0021]

[0022] Among them, S wAr is the water saturation after correction of the core; S wA is the water saturation of the core before washing oil and salt; Φ A is the first porosity of the core before washing oil and salt; Φ B It is the second porosity of the core after oil and salt washing.

[0023] Specifically, according to the resistivity increase rate and the corrected water saturation, the saturation index of the core before oil and salt washing is calculated, further comprising:

[0024] According to the resistance increase rate and the corrected water saturation, a second curve of the corrected core resistance increase rate versus water saturation is obtained by fitting and drawing;

[0025] The saturation index of the core before oil and salt washing is determined according to the second curve.

[0026] In a second aspect, the embodiments of the present invention further provide a device for determining a rock saturation index of an oil-wet reservoir, comprising:

[0027] An acquisition module, used to acquire the reservoir core to be tested;

[0028] A first measuring module is used to measure a first porosity and a first change curve of resistivity versus water saturation of the core before oil and salt washing;

[0029] A second measuring module is used to measure the second porosity and fully saturated solution resistivity of the core after oil and salt washing;

[0030] A first calculation module, used for calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution;

[0031] a correction module, configured to correct the water saturation of the core according to the first porosity, the second porosity and the first variation curve;

[0032] The calculation module is used to calculate the saturation index of the core before oil and salt washing according to the resistivity increase rate and the corrected water saturation.

[0033] By adopting the above technical scheme, a method and device for determining the saturation index of oil-wet reservoir rocks provided in this article can calculate the resistivity increase rate of the core and correct the water saturation of the core, and on this basis calculate the saturation index of the core under the original wettability conditions, thereby solving the problem that the saturation index obtained by the existing saturation index calculation method has a large error with the true value due to the change in reservoir wettability, and realizing the accurate calculation of the saturation index of the reservoir that is greatly affected by wettability.

[0034] In order to make the above and other purposes, features and advantages of this article more obvious and easy to understand, the following specifically cites preferred embodiments and describes them in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of this article or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of this article. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 A schematic diagram showing the steps of a method for determining the rock saturation index of an oil-wet reservoir provided in an embodiment of this invention is shown;

[0037] Figure 2 A schematic diagram of the steps for calculating the resistance increase rate of the core in the embodiment of this article is shown;

[0038] Figure 3A second curve showing the change of the core resistivity increase rate with water saturation after correction in the embodiment of this article is shown;

[0039] Figure 4 The curve showing the change of the core resistivity increase rate with water saturation after washing oil and salt is shown;

[0040] Figure 5 It shows the interpretation result diagram of a certain well and the resistivity experimental data diagram at formation temperature;

[0041] Figure 6 A schematic diagram of the structure of a device for determining the rock saturation index of an oil-wet reservoir provided in an embodiment of this invention is shown;

[0042] Figure 7 A schematic diagram of the structure of a computer device provided in an embodiment of this document is shown.

[0043] Description of the accompanying symbols:

[0044] 61. Get module;

[0045] 62. A first measuring module;

[0046] 63. A second measurement module;

[0047] 64. A first computing module;

[0048] 65. Correction module;

[0049] 66. A second calculation module;

[0050] 702. Computer equipment;

[0051] 704, processor;

[0052] 706. Memory;

[0053] 708, driving mechanism;

[0054] 710, input / output module;

[0055] 712. Input devices;

[0056] 714. Output devices;

[0057] 716. Presentation equipment;

[0058] 718. Graphical user interface;

[0059] 720, network interface;

[0060] 722. Communication link;

[0061] 724. Communication bus. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of this article to clearly and completely describe the technical solutions in the embodiments of this article. Obviously, the described embodiments are only part of the embodiments of this article, not all of the embodiments. Based on the embodiments of this article, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this article.

[0063] It should be noted that the terms "first", "second", etc. in the specification and claims of this article and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of this article described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, device, product or equipment that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or equipment.

[0064] In the prior art, when a core is obtained from a formation to be measured for measurement, the core's own wettability is changed due to pretreatment such as oil and salt washing, resulting in a large error between the measured core saturation index and the true value. Currently, there is no method to accurately obtain the rock saturation index under the original wettability conditions.

[0065] In order to solve the above problems, the embodiments of this article provide a method, device and computer equipment for determining the saturation index of oil-wet reservoir rocks, which can obtain an accurate saturation index under the original wettability conditions of the core. Figure 1 It is a schematic diagram of the steps of a method for determining the rock saturation index of an oil-wet reservoir provided in the embodiments of this article. This specification provides the method operation steps described in the embodiments or flow charts, but more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the steps among many orders, and does not represent the only order of execution. When the actual system or device product is executed, it can be executed in the order of the methods shown in the embodiments or the drawings or in parallel. Specifically, as Figure 1 As shown, the method may include:

[0066] S110: Obtaining a reservoir core to be tested.

[0067] In the embodiments of this specification, the core of the reservoir to be tested can be obtained from a certain depth underground, and the reservoir to be tested can be conventional sandstone or dense sandstone. Different reservoirs to be tested are affected by wettability to different degrees. In the embodiments of this specification, the method of obtaining the core from the reservoir to be tested is not specifically limited and can be selected according to actual working conditions.

[0068] S120: Determine a first porosity of the core before oil and salt washing and a first curve of resistivity changing with water saturation.

[0069] Generally, the core is washed with oil and salt before measuring the core parameters, which will cause the wettability conditions of the core to change.

[0070] The various parameters of the core before oil and salt washing in step S120 are measured by directly drying, vacuuming and saturating the core without oil and salt washing. Specifically, the core is dried at 90°C, and a mineral solution (for example, a salt water with a high mineralization degree) can be used to vacuum and saturate the core at room temperature and an axial pressure of 10MPa. Under constant external conditions (constant temperature and humidity), the core is placed in a holder, and the water-containing sample is displaced with crude oil. The core resistivity and water saturation of the core are measured and recorded during the displacement process.

[0071] In order to ensure the accuracy of the measured resistivity, the external environment should be kept constant during the measurement process. At the same time, the external environment should be adapted to the environment of the reservoir where the core is located, including: the external environment temperature should be adapted to the temperature of the reservoir where the core is located, the external environment humidity should be adapted to the humidity of the reservoir where the core is located, and the external environment pressure should be adapted to the pressure of the reservoir where the core is located.

[0072] The water saturation at each sampling time point can be determined by the following steps:

[0073] Obtaining a first mass of the core after saturation treatment, a second mass of the core at a target sampling time point, and a third mass of the core after drying;

[0074] The water saturation of the core at the target sampling time point is calculated based on the first mass, the second mass and the third mass, specifically:

[0075]

[0076] Among them, tx is the target sampling time point, S wAtx is the water saturation of the core at the target sampling time point before washing oil and salt, m tx is the second mass of the core at the target sampling time point; t0 is the time point corresponding to the core saturation treatment, m t0is the first mass of the core after saturation treatment; tt is the time node corresponding to the core drying, m tt is the third mass of the core after drying.

[0077] S130: Determine the second porosity and fully saturated solution resistivity of the core after oil and salt washing.

[0078] In the examples of this specification, the first porosity and the second porosity are measured and calculated using the standard GB / T 29172-2012 "Core Analysis Method", and the difference between the first porosity and the second porosity is only that they are measured before and after the core is washed with oil and salt, respectively.

[0079] It should be noted that, considering that the wettability of the core will change before and after oil and salt washing, the parameters of the core before oil and salt washing should be measured first in the specific experiment, including the first porosity and the first curve of resistivity changing with water saturation; and then the parameters of the core after oil and salt washing should be measured, including the second porosity and resistivity of the fully saturated solution.

[0080] S140: Calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution.

[0081] S150: Correcting the water saturation of the core according to the first porosity, the second porosity, and the first curve.

[0082] S160: Calculate the saturation index of the core before oil and salt washing according to the resistivity increase rate and the corrected water saturation.

[0083] A method for determining the saturation index of oil-wet reservoir rocks provided in an embodiment of the present specification provides a new method for calculating the resistivity of oil-wet reservoir rocks and correcting the water saturation of the acquired cores; on this basis, the saturation index of the cores under the original wettability conditions can be calculated, which solves the problem of the existing saturation index calculation method that the calculated saturation index has a large error with the true value due to the change in reservoir wettability, and realizes the accurate calculation of the saturation index of reservoirs that are greatly affected by wettability.

[0084] like Figure 2 As shown, in some feasible embodiments, step S140: calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution may include the following steps:

[0085] S210: Determine the oil resistivity of the core before washing the oil and salt.

[0086] The resistivity of the oil-bearing rock and the resistivity of the fully saturated solution can be measured by the following steps:

[0087] For the core samples taken from the well, they were dried at 90°C, and at room temperature and 10MPa, the cores were vacuumed and pressurized with a saturated 0.3 million ppm CaCl2 solution until the resistivity became stable. Then, the cores were placed in a holder and the water-bearing rocks were displaced with crude oil. During the displacing process, the resistivity of the oil-bearing rocks (denoted as R tA ), and the fully saturated solution resistivity of the core was measured at this time.

[0088] S220: Calculate the resistance increase rate of the core according to the resistivity of the fully saturated solution and the resistivity of the oil content.

[0089] Considering that reservoir wettability has a great influence on the resistivity increase rate, and the resistivity increase rate of rock is the ratio of the rock oil resistivity to the resistivity of a fully saturated solution, the resistivity increase rate of the core can be calculated based on the resistivity of the fully saturated solution and the oil resistivity.

[0090] Specifically, step S220: calculating the resistance increase rate of the core according to the fully saturated solution resistivity and the oil-containing resistivity, which may be:

[0091] Calculate using the following formula:

[0092]

[0093] Among them, I Ar is the resistivity increase rate of the core; R tA represents the oil resistivity of the core before washing oil and salt; R oB It indicates the fully saturated solution resistivity of the core after oil and salt washing. Subscript A means ahead, indicating before oil and salt washing; subscript B means behind, indicating after oil and salt washing; subscript r means revise, indicating the corrected parameter.

[0094] In some feasible embodiments, step S150: correcting the water saturation of the core according to the first porosity, the second porosity and the first curve, further comprises:

[0095] The water saturation of the core was corrected by the following formula:

[0096]

[0097] Among them, S wAr is the water saturation after correction of the core; S wA is the water saturation of the core before washing oil and salt; Φ A is the first porosity of the core before washing oil and salt; Φ BIt is the second porosity of the core after oil and salt washing.

[0098] In some feasible embodiments, step S160: calculating the saturation index of the core before oil and salt washing according to the resistivity increase rate and the corrected water saturation, further comprises:

[0099] According to the resistance increase rate and the corrected water saturation, a second curve of the corrected core resistance increase rate versus water saturation is obtained by fitting and drawing;

[0100] The saturation index of the core before oil and salt washing is determined according to the second curve.

[0101] Specifically, the second curve of the corrected core resistivity increase rate versus water saturation can be fitted by the least squares fitting method. The fitted second curve is an exponential relationship curve, and its exponential value is the saturation index. Figure 3 The second curve of the core resistivity increase rate after correction and the change of water saturation is shown in the figure. wAr is the water saturation after correction of the core, and the ordinate I Ar The resistance increase rate of the core obtained by the calculation method provided in the embodiment of this specification is fitted according to the corrected water saturation and the resistance increase rate to obtain a change relationship curve of y=0.9466x -5.388 , R 2 =0.9967, where R 2 is the correlation coefficient, which indicates the degree of agreement between the fitted second curve and the data. According to the second curve, the saturation index of the core is 5.3.

[0102] like Figure 4 The figure shows the curve of the core resistivity increase rate versus water saturation after oil and salt washing. wB is the water saturation of the core after oil and salt washing, and the ordinate I B is the resistance increase rate of the core after oil and salt washing, and the fitting curve is y=1.1166x -3.03 , R 2 =0.9987, where R 2 is the correlation coefficient. Figure 4 From the curve in, we can see that the saturation index of the core is 3.0 at this time.

[0103] contrast Figure 3 and Figure 4From the curves shown, it can be seen that the curves of the resistivity increase rate and the change of water saturation show a good linear relationship, but after washing oil and salt, the saturation index of the core is greatly reduced, which can explain that the oil and salt washing treatment of the core samples destroyed the original wettability of the reservoir, and the reservoir rock changed from oil-wet to water-wet to varying degrees.

[0104] like Figure 5 As shown, this is the interpretation result diagram of a certain well and the resistivity experimental data diagram at formation temperature. Figure 5 The first track on the left is the geological layering, and the arrow in the first track is the stratigraphic position of the core. The second track is the array induction logging curve, where AT90 is the resistivity with the deepest detection depth, and AT10 is the resistivity with the shallowest detection depth. The third track is the porosity logging curve, including density (DEN), acoustic wave (AC) and neutron (CNL) logging curves. The fourth track is the depth track. The fifth track is the interpretation conclusion. The sixth track is the comparative logging curve, including natural gamma (GR), natural potential (SP) and photoelectric absorption cross-section index (PE) logging curves. The seventh track is the permeability, including core permeability (CPERM) and calculated permeability (PERM). The eighth track is the porosity, including core porosity (CPOR) and total porosity (POR). The ninth track is the saturation, including core water saturation (CSW), core oil saturation (CSO) and calculated water saturation (SW). Among them, the SW calculated in the saturation track is measured using the method provided in the above embodiment, and the obtained water saturation (SW) is consistent with the water saturation (CSW) of core analysis. Figure 5 The right side of is the resistivity data at ground temperature. Figure 5 It can be seen on the right side that when the water saturation is 100%, the resistivity is 1Ω·m, which shows that the resistivity of the oil-wet water-saturated reservoir can also be very low. When the water saturation is 60%, the resistivity is about 15Ω·m; when the water saturation is 40%, the resistivity is about 100Ω·m. This shows that the resistivity ratio of the oil layer to the water layer in the oil-wet reservoir can reach 100 times. This shows that the experimental data well explains the logging response characteristics and is very helpful for the decision-making of the interpretation conclusion.

[0105] The method for determining the saturation index of oil-wet reservoir rocks provided in the embodiments of this specification addresses the problem of inaccurate measured resistivity increase rate and water saturation caused by changes in core wettability. The accurate resistivity increase rate and the water saturation are respectively calculated and corrected, and then the saturation index of the core under the original wettability conditions that is closer to the true value is calculated, providing a reliable basis for reservoir development research.

[0106] Based on the same inventive concept, a device for determining the rock saturation index of an oil-wet reservoir is also provided in the embodiments of this specification. Figure 6As shown, the device may include:

[0107] An acquisition module 61 is used to acquire a reservoir core to be tested;

[0108] A first determination module 62 is used to determine a first porosity and a first change curve of resistivity versus water saturation of the core before oil and salt washing;

[0109] The second measuring module 63 is used to measure the second porosity and fully saturated solution resistivity of the core after oil and salt washing;

[0110] A first calculation module 64, used to calculate the resistance increase rate of the core according to the resistivity of the fully saturated solution;

[0111] A correction module 65, configured to correct the water saturation of the core according to the first porosity, the second porosity and the first variation curve;

[0112] The second calculation module 66 is used to calculate the saturation index of the core before oil and salt washing according to the resistivity increase rate and the corrected water saturation.

[0113] In a specific embodiment, the first calculation module 64 calculates the resistance increase rate of the core according to the resistivity of the fully saturated solution and the resistivity of the oil content, which can be calculated by the following formula:

[0114]

[0115] Among them, I Ar is the resistivity increase rate of the core; R tA represents the oil resistivity of the core before washing oil and salt; R oB It indicates the fully saturated solution resistivity of the core after washing oil and salt. The subscript A means ahead, indicating before washing oil and salt; B means behind, indicating after washing oil and salt; the subscript r means revise, indicating the corrected parameter.

[0116] In a specific embodiment, the correction module 65 corrects the water saturation of the core according to the first porosity, the second porosity and the first curve, which can be performed by the following formula:

[0117]

[0118] Among them, S wAr is the water saturation after correction of the core; S wA is the water saturation of the core before washing oil and salt; Φ A is the first porosity of the core before washing oil and salt; Φ BIt is the second porosity of the core after oil and salt washing.

[0119] The beneficial effects obtained by the device provided in the embodiments of this specification are consistent with the beneficial effects obtained by the above method and will not be repeated here.

[0120] like Figure 7 As shown, a computer device provided in an embodiment of this invention, the oil-wet reservoir rock saturation index determination device in this specification can be a computer device in this embodiment, executing the above method of this invention. The computer device 702 may include one or more processors 704, such as one or more central processing units (CPUs), and each processing unit may implement one or more hardware threads. The computer device 702 may also include any memory 706, which is used to store any kind of information such as code, settings, data, etc. Non-limiting, for example, the memory 706 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory device, hard disk, optical disk, etc. More generally, any memory may use any technology to store information. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent a fixed or removable component of the computer device 702. In one case, when the processor 704 executes an associated instruction stored in any memory or a combination of memories, the computer device 702 may perform any operation of the associated instruction. The computer device 702 also includes one or more drive mechanisms 708 for interacting with any storage, such as a hard disk drive mechanism, an optical disk drive mechanism, etc.

[0121] The computer device 702 may also include an input / output module 710 (I / O) for receiving various inputs (via input devices 712) and for providing various outputs (via output devices 714). A specific output mechanism may include a presentation device 716 and an associated graphical user interface (GUI) 718. In other embodiments, the input / output module 710 (I / O), the input device 712, and the output device 714 may not be included, and the computer device 702 may be used as a computer device in a network. The computer device 702 may also include one or more network interfaces 720 for exchanging data with other devices via one or more communication links 722. One or more communication buses 724 couple the components described above together.

[0122] The communication link 722 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 722 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0123] Corresponds to Figure 1 to Figure 2 The method in this article also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above method are executed.

[0124] The embodiment of the present invention also provides a computer readable instruction, wherein when the processor executes the instruction, the program therein causes the processor to execute the following Figure 1 to Figure 2 The method shown.

[0125] The embodiment of the present invention also provides a computer program product, including at least one instruction or at least one program, wherein the at least one instruction or the at least one program is loaded and executed by a processor to implement the following Figure 1 to Figure 2 The method shown.

[0126] It should be understood that in the various embodiments of this document, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this document.

[0127] It should also be understood that in the embodiments of this article, the term "and / or" is only a description of the association relationship of the associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0128] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in terms of function in the above description. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this article.

[0129] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0130] In the several embodiments provided herein, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, or can be electrical, mechanical or other forms of connection.

[0131] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of this article.

[0132] In addition, each functional unit in each embodiment of this invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional unit.

[0133] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this article is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of this article. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0134] Specific embodiments are used in this article to illustrate the principles and implementation methods of this article. The description of the above embodiments is only used to help understand the methods and core ideas of this article. At the same time, for general technicians in this field, according to the ideas of this article, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on this article.

Claims

1. A method for determining the rock saturation index of an oil-wet reservoir, characterized in that: include: Obtaining the reservoir core to be tested; Determine a first porosity of the core before washing oil and salt and a first curve of resistivity changing with water saturation; Determining the second porosity and fully saturated solution resistivity of the core after washing oil and salt; Calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution; According to the first porosity and the second porosity, the values ​​of each water saturation of the core in the first curve are corrected: Among them, S wAr(i) S is the corrected water saturation of the core at the i-th sampling time point in the first curve; wA(i) is the water saturation of the core before oil and salt washing at the i-th sampling time point in the first curve; Φ A is the first porosity of the core before washing oil and salt; Φ B is the second porosity of the core after oil and salt washing; The saturation index of the core before oil and salt washing is calculated based on the resistivity increase rate and the corrected water saturation.

2. The method according to claim 1, characterized in that Calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution includes: Determining the oil resistivity of the core before washing oil and salt; The resistivity increase rate of the core is calculated based on the resistivity of the fully saturated solution and the resistivity of the oil content.

3. The method according to claim 2, characterized in that The resistance increase rate of the core is calculated by the following formula: Among them, I Ar is the resistivity increase rate of the core; R tA represents the oil resistivity of the core before washing oil and salt; R oB It represents the resistivity of the fully saturated solution of the core after washing oil and salt.

4. The method according to claim 1, characterized in that Calculating the saturation index of the core before oil and salt washing according to the resistivity increase rate and the corrected water saturation further includes: According to the resistance increase rate and the corrected water saturation, a second curve of the corrected core resistance increase rate versus water saturation is obtained by fitting and drawing; The saturation index of the core before oil and salt washing is determined according to the second curve.

5. A device for determining the rock saturation index of an oil-wet reservoir, characterized in that: include: An acquisition module, used to acquire the reservoir core to be tested; A first determination module is used to determine a first porosity of the core before oil and salt washing and a first curve of resistivity versus water saturation; A second measuring module is used to measure the second porosity and fully saturated solution resistivity of the core after oil and salt washing; A first calculation module, used for calculating the resistance increase rate of the core according to the resistivity of the fully saturated solution; A correction module, used to correct the values ​​of each water saturation of the core in the first curve according to the first porosity and the second porosity: Among them, S wAr(i) S is the corrected water saturation of the core at the i-th sampling time point in the first curve; wA(i) is the water saturation of the core before oil and salt washing at the i-th sampling time point in the first curve; Φ A is the first porosity of the core before washing oil and salt; Φ B is the second porosity of the core after oil and salt washing; The calculation module is used to calculate the saturation index of the core before oil and salt washing according to the resistivity increase rate and the corrected water saturation.

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