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CN-122014220-A - Method and device for calculating water saturation of mixed stratum of water-drive reservoir

CN122014220ACN 122014220 ACN122014220 ACN 122014220ACN-122014220-A

Abstract

The invention relates to a calculation method and a device for water saturation of a water-displacement reservoir mixed stratum, belonging to the technical field of petroleum logging, wherein the method comprises the steps of obtaining parameters of an Alqi formula based on first physical parameters of a target rock sample; the method comprises the steps of obtaining a second physical parameter of a target rock sample, constructing a dynamic representation model of the mineralization degree of mixed formation water corresponding to the target rock sample, determining a first relation between the water saturation of the target rock sample under different mineralization degree brine displacement and rock resistivity, obtaining an equivalent ion exchange rate based on the first physical parameter, the second physical parameter, an Alqi formula and the first relation, and obtaining the water saturation based on the equivalent ion exchange rate and the dynamic representation model of the mineralization degree of the mixed formation water. The method improves the calculation accuracy of the water saturation of the mixed stratum of the water-drive reservoir.

Inventors

  • WANG JINGCI

Assignees

  • 长江大学

Dates

Publication Date
20260512
Application Date
20260324

Claims (10)

  1. 1. The method for calculating the water saturation of the mixed stratum of the water-flooding reservoir is characterized by comprising the following steps of: Obtaining parameters of an Alqi formula based on first physical parameters of the target rock sample, the first physical parameters including porosity, resistivity, and water saturation; obtaining a second physical parameter of the target rock sample, wherein the second physical parameter comprises a maximum pore-throat communication radius, a pore-throat radius, a median pressure and a maximum mercury saturation; constructing a dynamic characterization model of the mineralization degree of the mixed stratum water corresponding to the target rock sample; determining a curve relationship between water saturation and rock resistivity of a target rock sample under different mineralization degree brine displacement; Equivalent ion exchange rate obtained based on the first physical parameter, the second physical parameter and the Alqi formula; And obtaining the water saturation based on the equivalent ion exchange rate and the mixed stratum water mineralization dynamic characterization model.
  2. 2. The method for calculating water saturation of a water-reservoir mixed formation of claim 1, wherein the first physical parameter is determined by a rock-electric experiment.
  3. 3. The method for calculating water saturation of a water-reservoir hybrid formation according to claim 1, wherein the second physical parameter is determined by mercury intrusion experiments.
  4. 4. The method for calculating the water saturation of the mixed stratum of the water-flooding reservoir according to claim 1, wherein the expression of the dynamic characterization model of the water mineralization of the mixed stratum is as follows: In the formula, Represents the mineralization degree of the water in the mixed stratum, Represents the mineralization degree of the water in the original stratum, Representing the original water saturation level of the water, Represents the equivalent ion exchange rate of the ion exchange membrane, The mineralization of the solution is shown where the injected water has been fully ion exchanged with the original formation water.
  5. 5. The method for calculating the water saturation of the mixed stratum of the water-flooding reservoir according to claim 4, wherein the dynamic characterization model of the water mineralization of the mixed stratum is obtained based on a first formula and a second formula: the expression of the first formula is: The expression of the second formula is: In the formula, Indicating the ratio of the total injected water quantity to the oil and gas yield of the stratum, Indicating the effective porosity of the reservoir, Indicating the water saturation of the reservoir at a certain moment, Representing the original water saturation level of the water, Represents the equivalent ion exchange rate of the ion exchange membrane, Indicating the degree of mineralization of the solution, Indicating the mineralization of the injected water.
  6. 6. The method for calculating the water saturation of a mixed formation of a water-flooding reservoir according to claim 1, wherein the equivalent ion exchange rate has a value ranging from 0 to 1.
  7. 7. The method for calculating water saturation of a mixed formation of a water displacement reservoir according to claim 6, wherein when the equivalent ion exchange rate is 0, all of the original formation water which does not participate in ion exchange is original formation water, and when the equivalent ion exchange rate is 1, all of the original formation water is injected water which is completely ion exchanged.
  8. 8. A device for calculating water saturation of a water-displacement reservoir mixed formation, comprising: The parameter acquisition module of the Alqi formula is used for acquiring parameters of the Alqi formula based on first physical parameters of the target rock sample, wherein the first physical parameters comprise porosity, resistivity and water saturation; the second physical parameter acquisition module is used for acquiring second physical parameters of the target rock sample, wherein the second physical parameters comprise a maximum pore throat communication radius, a pore throat radius, a median pressure and a maximum mercury saturation; The water mineralization dynamic characterization model acquisition module is used for constructing a mixed stratum water mineralization dynamic characterization model corresponding to the target rock sample; The curve relation acquisition module is used for determining the curve relation between the water saturation and the rock resistivity of the target rock sample under the displacement of the saline water with different mineralization degrees; The equivalent ion exchange rate acquisition module is used for obtaining the equivalent ion exchange rate based on the first physical parameter, the second physical parameter and the Alqi formula; and the water saturation acquisition module is used for obtaining the water saturation based on the equivalent ion exchange rate and the dynamic characterization model of the mixed formation water mineralization.
  9. 9. An electronic device comprising a memory and a processor, wherein, The memory is used for storing programs; The processor is coupled to the memory for executing the program stored in the memory to implement the steps in a method for calculating water saturation of a water-reservoir hybrid formation according to any one of claims 1 to 7.
  10. 10. A computer readable storage medium storing a computer readable program or instructions which when executed by a processor is capable of carrying out the steps of a method of calculating water saturation of a water reservoir mixed formation as claimed in any one of claims 1 to 7.

Description

Method and device for calculating water saturation of mixed stratum of water-drive reservoir Technical Field The invention relates to the technical field of petroleum well logging, in particular to a method and a device for calculating water saturation of a water-displacement reservoir mixed stratum. Background The water displacement reservoir supplements stratum energy through water injection, gravity difference is formed by utilizing the density difference of water and oil (water density > oil density), and the water displaces crude oil from the bottom or the edge to form an oil-water mixed flow area. The conventional open hole water saturation logging interpretation method is that firstly, natural potential logging data are utilized to estimate the resistivity of mixed formation water, then the estimated resistivity of mixed formation water is utilized to be substituted into a saturation calculation model (such as an Alqi formula model) to calculate the water saturation. However, the influence of multiple factors (influence of the salt concentration ratio in the formation water and the mud filtrate, influence of lithology, influence of temperature, influence of the salt property in the formation water and the mud filtrate, influence of the formation resistivity, influence of the formation thickness, influence of the well diameter expansion and the mud, etc.) on the determination result is great. Especially for a clear water and sewage alternate injection type water displacement reservoir (the change rule of mixed formation water is more complex) or a thin flooding layer (the electrical characteristics such as natural potential and the like are not obvious or distorted), the difference of the mixed formation water characteristics among different layers is not negligible, but the degree of influence of natural potential logging data is obviously increased, so that the mixed formation water resistivity cannot be calculated by using the natural potential logging data. In order to solve the problem, the formation water resistivity is selected according to the relative reduction of the resistivity log of the water reservoir, the baseline offset of the natural potential curve, the morphological characteristics of the log and the like, so that the method can also be used as a countermeasure. In addition, a learner uses the water content data of the initial production stage of the development well as a basis, and then, in combination with the static research result, inverts the mixed formation water resistivity of the production layer, so as to calibrate the mud filtrate resistivity in the well shaft, and finally, the mixed formation water resistivity of each small layer in the longitudinal direction is calculated by applying the basic principle of natural potential well logging. When the influence factors of the natural potential logging data are more, the method overcomes the defect that the resistivity of the mixed formation water is obtained by simply utilizing the natural potential logging data to a certain extent, but the method has the defects in the aspects of calculation speed and precision. In addition, it is widely accepted that the saturation index, an important parameter in the saturation calculation model, will change somewhat as the water saturation increases. However, currently, when the water saturation is obtained, since the water saturation is unknown, a relatively fixed saturation index is required, which is also a factor limiting the accuracy of calculation of the water saturation. In summary, a method for improving the calculation accuracy of the water saturation of the mixed stratum of the water-flooding reservoir is lacking in the prior art. Disclosure of Invention In view of the foregoing, it is necessary to provide a method, a device, an electronic device and a medium for calculating the water saturation of a water-flooding reservoir mixed stratum, so as to solve the problem of low calculation accuracy of the water saturation of the water-flooding reservoir mixed stratum in the prior art. In order to solve the problems, in a first aspect, the invention provides a method for calculating water saturation of a mixed stratum of a water-flooding reservoir, which comprises the following steps: Obtaining parameters of an Alqi formula based on first physical parameters of the target rock sample, the first physical parameters including porosity, resistivity, and water saturation; obtaining a second physical parameter of the target rock sample, wherein the second physical parameter comprises a maximum pore-throat communication radius, a pore-throat radius, a median pressure and a maximum mercury saturation; constructing a dynamic characterization model of the mineralization degree of the mixed stratum water corresponding to the target rock sample; determining a curve relationship between water saturation and rock resistivity of a target rock sample under different mineralization degree brine displ