Method for correcting core oil saturation by using well logging resultant curve

Abstract

The invention provides a method for correcting core oil saturation by using a well logging resultant curve. The method comprises the following steps that a So-depth diagram is drawn according to firstmodified core oil saturation data So; according to a fitting formula of the oil saturation of a work area, a well logging resultant curve Sy is obtained, and a new well logging curve Sy' is obtainedthrough equal scaling and translation of the well logging resultant curve Sy; the core oil saturation data So is horizontally projected to the new well logging curve Sy' to obtain new oil saturation data So'; and an average value So'' of the data point So before projection and the data point So' after projection is taken as the final core oil saturation of which the relative size is corrected. According to the method for correcting the core oil saturation by using the well logging resultant curve, underground undisturbed stratum data is adopted to correct core experimental data which is takento the earth surface, so that real situations of an underground undisturbed core and a stratum are realized as faithful as possible, understanding is easy, the method is simple and convenient, and thefeasible method for correcting and improving the relative size of the core oil saturation is provided.

Description

technical field [0001] The invention relates to the technical field of oilfield development, in particular to a method for correcting the oil saturation of rock cores by using well logging synthetic curves. Background technique [0002] At present, the factors causing the core oil saturation error are complicated, and the corresponding correction methods are not suitable: [0003] 1. After the core is taken out, it is generally stored for more than half a year before the experiment is started. There are many links that will cause significant changes in saturation, and the influencing factors are many and complex: ①Dissolved gas drives the liquid to discharge outward, contributing 5 to 30% to the saturation error; ②Drilling fluid invasion, even if there is a 1m mudstone cap, the core sealing rate may still be unqualified, contributing 0-20% of the error; ③The high temperature generated by core cutting will volatilize all the oil and water, contributing 0-30% to the overall er...

AI Technical Summary

Problems solved by technology

[0002] At present, the factors causing the core oil saturation error are complicated, and the corresponding correction methods are not suitable:

[0003] 1. After the core is taken out, it is generally stored for more than half a year before the experiment is started. There are many links that will cause significant changes in saturation, and the influencing factors are many and complex: ①Dissolved gas drives the liquid to discharge outward, contributing 5 to 30% to the saturation error; ②Drilling fluid invasion, even if there is a 1m mudstone cap, the core sealing rate may still be unqualified, contributing 0-20% of the error; ③The high temperature generated by core cutting will volatilize all the oil and water, contributing 0-30% to the overall error; ④Core room temperature Volatilization under long-term storage contributes 5-20% to the error; ⑤ When the overburden pressure on the surface is reduced and the core pores expand, it contributes 5-20% to the saturation error; ⑥ Long-term storage in a -80°C ultra-low temperature storage box, water expands after freezing Cause the core pores to expand and crack, or the entire core to expand and crack, which contributes 5 to 20% to the saturation error; ⑦The human error and system error in the experiment process are about 5%

[0004] 2. Although the factors causing the error of oil saturation are complicated, judging from the logging curve reflecting oiliness, the response of the logging curve to the relative level of oil saturation is relatively accurate;

Images