CN-115455733-B - Evaluation method for residual oil re-enrichment quality

CN115455733BCN 115455733 BCN115455733 BCN 115455733BCN-115455733-B

Abstract

The invention provides an evaluation method of residual oil re-enrichment quality, which comprises the steps of (1) obtaining the distribution of residual oil saturation before enrichment and after enrichment through physical simulation or numerical simulation research of residual oil re-enrichment, (2) calculating to obtain a shunt value curve, (3) calculating the distribution of residual oil enrichment state values before enrichment and after enrichment, (4) determining an evaluation index and an evaluation standard of residual oil re-enrichment quality, and (5) evaluating the residual oil re-enrichment quality. The evaluation method for the re-enrichment quality of the residual oil of the high-water-content oil reservoir has the characteristics of simplicity in operation, rapidness in calculation and definite target, and the residual oil of the re-enrichment of the high-water-content oil reservoir can be intuitively divided into different types, so that decision references are provided for the digging of the residual oil, and the evaluation method has practical engineering application values.

Inventors

ZHANG SHUNKANG
LIU BINGGUAN
SUN DONGSHENG
YOU QIDONG
GE ZHENGJUN
LUO YUHAN

Assignees

中国石油化工股份有限公司
中国石油化工股份有限公司江苏油田分公司

Dates

Publication Date: 20260505
Application Date: 20221009

Claims (5)

1. The method for evaluating the re-enrichment quality of the residual oil is characterized by comprising the following steps of: (1) The method comprises the steps of carrying out fine oil reservoir description on a target unit, carrying out water flooding physical simulation experiments in combination with geological parameters of the target unit, and obtaining the saturation distribution of the residual oil before and after enrichment; (2) The method comprises the steps of calculating a shunt volume curve based on the target unit, combining the relative permeability curve of the target unit, calculating a shunt volume curve of a region through a shunt volume equation, dividing the shunt volume curve into 3 regions according to a water content grading standard, wherein saturation points corresponding to the 3 regions are boundary points of oil content saturation grading, and defining an enrichment state value To represent the enrichment status of the remaining oil in each zone; (3) Calculating the distribution of the residual oil enrichment state values before and after enrichment, wherein the step (3) further comprises the following steps: Evaluating the enrichment quality of the residual oil according to the enrichment degree index and the potential index; the enrichment degree index is calculated as follows: in the formula: M 2 , which is the corresponding area of the highly enriched region after re-enrichment; M 2 , which is the corresponding area of the medium enrichment region after re-enrichment; M 2 , which is the corresponding area of the non-enriched area after re-enrichment; m is the number of grids corresponding to the highly enriched area after re-enrichment; n is the number of grids corresponding to the medium enrichment area after re-enrichment; k is the number of grids corresponding to the non-enrichment area after re-enrichment; i is a subscript; the corresponding residual oil enrichment state value before the residual oil of the grid i is re-enriched; the calculation formula of the potential index is as follows: Wherein, the In the formula: i. j is a subscript; the number of the residual oil blocks corresponding to the i-th type of residual oil after re-enrichment is one; m 2 , which is the corresponding area of the j-th oil-containing block of the i-th residual oil after re-enrichment; M 2 , which is the area corresponding to the largest oil-containing block of the i-th residual oil after re-enrichment; the j-th oil-containing block is the i-th residual oil after re-enrichment; Normalized area variance for i-th type of residual oil after re-enrichment, dimensionless; The weight value of the potential weight corresponding to the i-th type of residual oil after re-enrichment is 2 for the highly enriched residual oil, 1 for the moderately enriched residual oil, and 0.5 for the non-enriched residual oil; (4) Determining an evaluation index and an evaluation standard of the re-enrichment quality of the residual oil; (5) And evaluating the re-enrichment quality of the residual oil.
2. The method for evaluating the re-enrichment quality of residual oil according to claim 1, wherein the residual oil is considered to be highly enriched therein when the water content is 0 to 20% and the saturation of the residual oil is S 1 to 1, and the value is assigned 2, When the water content is 20% -90%, the water content is medium-high, the residual oil is regarded as being moderately enriched in the water content, and the oil saturation is S 2 ～S 1, and assigned 1, When the water content is 90% -100%, the water content is very high, the residual oil is regarded as not being enriched at the position, the oil saturation is 0~S 2 , and the value is assigned 0.5.
3. The method for evaluating the quality of the re-enrichment of residual oil according to claim 2, wherein the step (3) comprises: And respectively calculating the distribution of the residual oil enrichment state values before enrichment and after enrichment according to the saturation points corresponding to the 3 areas of the shunt flow curve and the enrichment state values corresponding to the areas based on the distribution of the residual oil saturation before enrichment and after enrichment.
4. The method for evaluating the quality of reaumn-enriched remaining oil according to claim 3, wherein the step (4) comprises: The method comprises the steps of taking an enrichment degree index as an abscissa and a utilization potential index as an ordinate, when the enrichment degree index and the utilization potential index of the residual oil are both larger than 1, indicating that the residual oil is better in re-enrichment quality, defining as class A residual oil, defining as class B residual oil when the enrichment degree index of the residual oil is larger than 1 and the utilization potential index is smaller than 1, defining as class C residual oil when the enrichment degree index of the residual oil is smaller than 1 and the utilization potential index is larger than 1, and defining as class D residual oil when the enrichment degree index of the residual oil and the utilization potential index of the residual oil are both smaller than 1, indicating that the residual oil is worst in re-enrichment quality.
5. The method for evaluating the quality of reaumn-enriched remaining oil according to claim 4, wherein the step (5) comprises: And (3) according to the evaluation standard of the re-enrichment quality of the residual oil established in the step (4), obtaining the enrichment degree index and the potential index of the residual oil after re-enrichment in combination with the step (3), and finally determining the quality of the residual oil after re-enrichment.

Description

Evaluation method for residual oil re-enrichment quality Technical Field The invention belongs to the field of oilfield development, and particularly relates to an evaluation method of residual oil re-enrichment quality. Background The existing research means mainly utilizes theoretical formulas, physical simulation and numerical simulation methods to develop research on the secondary enrichment sensitive factors of the residual oil in the high-water-content oil-stopping production reservoir so as to determine the primary control factors of secondary enrichment of the residual oil, and an accurate evaluation method is not formed on the secondary enrichment quality of the residual oil. The existing research means cannot form an accurate evaluation method for the re-enrichment quality of the residual oil, and can effectively guide the lack of the excavation of the residual oil of the high-water-content oil reservoir. Disclosure of Invention The evaluation method for the re-enrichment quality of the residual oil of the high-water-content oil reservoir has the characteristics of simplicity in operation, rapidness in calculation and definite target, and the residual oil of the re-enrichment of the high-water-content oil reservoir can be intuitively divided into different types, so that decision references are provided for the digging of the residual oil, and the evaluation method has practical engineering application values. The evaluation method of the residual oil re-enrichment quality comprises the steps of (1) obtaining the residual oil saturation distribution before enrichment and after enrichment through physical simulation or numerical simulation research of the residual oil re-enrichment, (2) calculating to obtain a shunt value curve, (3) calculating the residual oil enrichment state value distribution before enrichment and after enrichment, (4) determining the evaluation index and the evaluation standard of the residual oil re-enrichment quality, and (5) evaluating the residual oil re-enrichment quality. The method comprises the step (1) of carrying out fine oil reservoir description on a target unit, and carrying out water flooding physical simulation experiments in combination with geological parameters of the target unit to obtain the distribution of the saturation of the residual oil before and after enrichment. Wherein, step (2) includes: based on the target unit, combining the relative permeability curve of the target unit, and calculating to obtain a shunt value curve of the region through a shunt value equation; According to the water content grading standard, dividing the shunt volume curve into 3 areas, wherein saturation points corresponding to the 3 areas are boundary points of oil saturation grading, and defining an enrichment state value alpha to represent the enrichment state of residual oil in each area, namely, when the water content is 0-20%, the residual oil is considered to be highly enriched at the position, the oil saturation is S 1 -1, and the alpha is assigned to be 2, when the water content is 20-90%, the residual oil is considered to be moderately enriched at the position, the oil saturation is S 2～S1, and the alpha is assigned to be 1, and when the water content is 90-100%, the residual oil is considered to be not enriched at the position, the oil saturation is 0~S 2, and the alpha is assigned to be 0.5. Wherein, step (3) includes: And respectively calculating the distribution of the residual oil enrichment state values before enrichment and after enrichment according to the saturation points corresponding to the 3 areas of the shunt flow curve and the enrichment state values corresponding to the areas based on the distribution of the residual oil saturation before enrichment and after enrichment. Wherein, step (3) further comprises: Evaluating the enrichment quality of the residual oil according to the enrichment degree index and the potential index; the enrichment degree index is calculated as follows: in the formula: S1 i is the corresponding area of the highly enriched region after re-enrichment, m 2; S2 i is the corresponding area of the medium degree enrichment region after re-enrichment, m 2; S3 i is the corresponding area of the non-enriched region after re-enrichment, m 2; m is the number of grids corresponding to the highly enriched area after re-enrichment; n is the number of grids corresponding to the medium enrichment area after re-enrichment; k is the number of grids corresponding to the non-enrichment area after re-enrichment; i is a subscript; Alpha i is the corresponding residual oil enrichment state value before the residual oil of the grid i is re-enriched; the calculation formula of the potential index is as follows: Wherein, the In the formula: i. j is a subscript; n i is the number of the residual oil blocks corresponding to the i-th type residual oil after re-enrichment; s ij is the corresponding area of the j-th oil block of the i-th residual oil after