CN-122017206-A - Shale oil maximum movable oil quantity evaluation method, system and application based on centrifugation

CN122017206ACN 122017206 ACN122017206 ACN 122017206ACN-122017206-A

Abstract

The invention discloses a shale oil maximum movable oil quantity evaluation method, a shale oil maximum movable oil quantity evaluation system and an application thereof based on centrifugation, and relates to the technical field of unconventional oil and gas geology evaluation; the method comprises the steps of obtaining total oil content Qoil and free oil content Qfoil in a fresh closed shale sample, determining movable oil content Qmov based on the free oil content Qfoil and total oil content Qoil2 of the fresh closed shale sample after centrifugation, establishing relations between Qfoil and Qmov of different types, determining bound oil quantity M_th of the fresh closed shale sample of different types, establishing a shale oil maximum movable quantity model based on the free oil content Qfoil and the bound oil quantity M_th, obtaining continuous free oil quantity Qfoil and TOC according to a logging curve, and obtaining shale oil maximum movable quantity vertical distribution through the shale oil maximum movable quantity model. The method predicts the maximum movable quantity of the shale oil in the vertical direction, can realize the fine evaluation of the maximum movable quantity of the shale oil, and provides reliable basic parameters for evaluating the dessert of the shale oil, thereby improving the exploration precision of the shale oil.

Inventors

YANG LIANG
LI ZHONGCHENG
XUE WEI
Xing Jilin
LIU HONGCHAO

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20241111

Claims (12)

1. The method for evaluating the maximum movable oil quantity of the shale oil based on centrifugation is characterized by comprising the following steps of: acquiring total oil content Qoil and free oil content Qfoil in a fresh closed shale sample; Determining a movable oil quantity Qmov based on the free oil quantity Qfoil and the total oil content Qoil2 of the fresh closed shale sample after centrifugation; Establishing relationships of Qfoil and Qmov of different types according to the inflection point relationship of TOC and accumulated movable efficiency curve of the fresh closed shale sample, and determining the bound oil quantity M_th of the fresh closed shale sample of different types; Establishing a shale oil maximum momentum model based on free oil quantity Qfoil and bound oil quantity M_th classification type; and obtaining continuous free oil quantity Qfoil and TOC according to the logging curve, and then obtaining the maximum movable quantity vertical distribution of the shale oil through a maximum movable quantity model of the shale oil.
2. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation according to claim 1 is characterized in that total oil content Qoil and free oil quantity Qfoil in a fresh closed shale sample are obtained based on a two-dimensional nuclear magnetic resonance test, wherein the two-dimensional nuclear magnetic resonance test is carried out by removing closed liquid on the surface of the fresh closed shale sample; calibrating a nuclear magnetic resonance analysis instrument, and placing the processed fresh closed shale sample into the instrument for testing to obtain a series of echo strings; Then performing nuclear magnetic resonance inversion to obtain a T 1 -T 2 spectrum, and performing threshold segmentation on the T 1 -T 2 spectrum through a two-dimensional nuclear magnetic resonance fluid identification plate to obtain the signal quantity of each fluid component; and carrying out mass conversion on the signal quantity through a fluid calibration equation to obtain the corresponding total oil content Qoil and free oil quantity Qfoil.
3. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation as claimed in claim 1, wherein the movable oil quantity Qmov is determined based on the free oil quantity Qfoil and the total oil content Qoil2 of the fresh closed shale sample after centrifugation by the following steps: Placing a fresh closed shale sample subjected to two-dimensional nuclear magnetic resonance testing into a centrifuge for centrifugation, and then rapidly placing the fresh closed shale sample into a nuclear magnetic resonance analysis instrument for calibration to obtain a series of echo strings; Then, obtaining a T 1 -T 2 spectrum through nuclear magnetic resonance inversion, and carrying out threshold segmentation on the T 1 -T 2 spectrum through a two-dimensional nuclear magnetic resonance fluid identification plate to obtain the signal quantity of each fluid component; the corresponding total oil content Qoil2 after centrifugation is obtained through a fluid calibration equation, and the movable oil quantity is Qmov = Qoil1-Qoil2.
4. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation as claimed in claim 1 is characterized in that the TOC of the fresh closed shale sample is obtained by grinding the fresh closed shale sample to 100-120 meshes, adding excessive hydrochloric acid solution to remove inorganic carbon, dripping water to remove hydrochloric acid, and finally heating in a CS-230 carbon-sulfur analyzer to obtain TOC.
5. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation according to claim 1, wherein the accumulated movable efficiency curve is obtained by dividing movable oil quantity Qmov by free oil quantity Qfoil of a fresh closed shale sample, namely n= Qmov/Qfoil, and accumulating different sample n values according to TOC from small to large to obtain a curve of the accumulated movable efficiency n changing with TOC.
6. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation according to claim 5, wherein TOC intervals are divided according to inflection points of a change curve, and different types of movable oil quantities Qmov and Qfoil are obtained by a linear fitting method based on the intervals, wherein Qmov =a is Qfoil +b, and wherein-b/a is the bound oil quantity of the type of sample.
7. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation according to claim 1, wherein the maximum movable oil quantity model of shale oil is qm= Qfoil-M_th.
8. The method for evaluating the maximum movable oil quantity of shale oil based on centrifugation according to claim 1, wherein the relation between a logging curve and TOC and free oil quantity Qfoil is established based on the logging curve and core analysis data, TOC and free oil quantity Qfoil are predicted in the vertical direction, continuous constraint oil quantity M_th is obtained based on continuous TOC, and further vertical distribution Qm of the maximum movable quantity of shale oil is obtained through a shale oil maximum movable quantity model.
9. A system for evaluating maximum movable oil quantity of shale oil based on centrifugation, comprising: The total oil content and free oil content point value acquisition module is used for acquiring total oil content Qoil and free oil content Qfoil in the fresh closed shale sample; the movable oil quantity point value acquisition module is used for determining a movable oil quantity Qmov based on the free oil quantity Qfoil and the total oil content Qoil2 of the fresh closed shale sample after centrifugation; The constraint oil quantity point value acquisition module is used for establishing the relations of Qfoil and Qmov of different types according to the inflection point relation of the TOC and the accumulated movable efficiency curve of the fresh closed shale samples and determining the constraint oil quantity M_th of the fresh closed shale samples of different types; the model building module is used for building a shale oil maximum momentum model based on the free oil quantity Qfoil and the constraint oil quantity M_th classification type; And the shale oil maximum movable quantity acquisition module is used for obtaining continuous free oil quantity Qfoil and TOC according to a logging curve, and then acquiring the shale oil maximum movable quantity vertical distribution through a shale oil maximum movable quantity model.
10. A method for evaluating maximum movable oil quantity of shale oil based on centrifugation as claimed in any one of claims 1-8, applied to screening of shale oil development intervals.
11. An electronic device comprising a memory, a processor and a computer program stored to run on the memory, the processor implementing a centrifugation-based shale oil maximum movable oil quantity evaluation method according to any one of claims 1-8 when executing the program.
12. A computer readable storage medium having stored thereon a computer program which when executed by a processor implements a method of evaluating maximum movable oil mass of shale oil based on centrifugation as claimed in any one of claims 1-8.

Description

Shale oil maximum movable oil quantity evaluation method, system and application based on centrifugation Technical Field The invention relates to the technical field of unconventional oil and gas geology evaluation, in particular to a shale oil maximum movable oil quantity evaluation method, system and application based on centrifugation. Background Shale oil is a liquid hydrocarbon that remains in the pore and fracture system of organic-rich formations, with the properties of in situ and short-range migration. Although the land shale oil resources in China have huge potential, only the recoverable shale oil has economic value. The mobility of the land shale under the influence of strong heterogeneity and various factors brings great challenges to exploration and development work. Therefore, the main control factors of the shale oil mobility are determined, the characteristics of the shale oil are accurately represented, and a scientific shale oil movable oil mass evaluation model is established, so that the method has important significance for remarkably improving the exploration and development efficiency of the shale oil. Currently, the main evaluation methods for shale oil momentum are divided into three main categories: The first category is the geochemical parametric method, which uses an index of S1/TOC, also known as the Oil Saturation Index (OSI), to evaluate shale oil' S ability to perform. Jarvie, by studying the sea shale oil productivity characteristics of multiple basins in the United states, found that the value of S1 is generally higher than its TOC value in shale intervals with productivity, thus setting 100 XS 1/TOC >100mg/g as a criterion for selecting advantageous shale intervals. However, the specification of this standard does not fully take into account the differences between the land-phase shale oil and the sea-phase shale oil, so whether it is suitable for shale oil resource evaluation in China is still controversial. In addition, the shale oil in China has the characteristics of high viscosity, high clay content, low maturity, strong heterogeneity and the like, and the characteristics cause the difference of the movable lower limits of the shale oil in different basins. Meanwhile, in the measurement process of S1, different experimental methods and preservation conditions can cause significant differences in core test results, so that the direct application of the OSI method generates contradiction between actual productivity and S1, and the accuracy of shale oil mobility evaluation is limited. The second type of evaluation method is based on one-dimensional nuclear magnetic resonance-centrifugation technology. The method determines a T 2 cut-off value by comparing differences in one-dimensional nuclear magnetic resonance T 2 spectra before and after centrifugation, the portion above the cut-off value being considered as the mobile fluid and the portion below the cut-off value being considered as the confining fluid. Further, the method also utilizes the change of the nuclear magnetic resonance T 2 spectral integral quantity before and after centrifugation to calculate the movable quantity of shale oil through the conversion of the signal quantity. It is noted, however, that from the T 2 spectrum before and after centrifugation, even portions above the T 2 cutoff may contain partially bound fluid, while portions below the T 2 cutoff may contain partially mobile fluid. In addition, shale of different lithofacies and TOC (total organic carbon) content have significant differences in T 2 cut-off values, so using a uniform T 2 cut-off value to evaluate the shale's movable amount can produce large errors. In addition, the one-dimensional nuclear magnetic resonance technology has limitation in distinguishing free oil quantity and adsorbed oil quantity in shale, and even if a method such as formula calculation and Gaussian function is adopted to decompose the nuclear magnetic T 2 spectrum to identify fluid, larger errors can still be generated, and complex relation between movable quantity and adsorption effect is difficult to accurately reveal. In addition, the selection of centrifugal force and centrifugal time has an important influence on the evaluation result of the method, so that the corresponding relation between the production pressure difference and the selected centrifugal force in the actual development process needs to be clear in the application process. The third type of evaluation method is based on the adsorption-free oil model. According to the method, free oil quantity and adsorbed oil quantity in shale are quantitatively evaluated by utilizing experimental means such as nuclear magnetic resonance or step pyrolysis, and the free oil quantity is regarded as the maximum potential movable quantity of shale oil. However, there are several limitations to this approach. Firstly, due to the loss of the light hydrocarbon part of the sample during the placing process, the free