Method for improving interpretation accuracy of oil-bearing saturation in tight sandstone reservoir

Abstract

The invention relates to a method for improving the interpretation accuracy of oil-bearing saturation in a tight sandstone oil reservoir. On the premise that the resistivity of rocks in the formation,the oil in pores and formation water in pores are different in magnitude, rocks and crude oil are regarded as high-resistance bodies, and low-resistance formation water is separated for separate study. The idea of (pore volume-formation water volume) / pore volume is used to study the oil-bearing saturation of the reservoir. According to the invention, a used pure oil layer and pure water layer canbe verified together through well logging, core and production; the oil and water layer data can be acquired based on ordinary core analysis, so that the experimental workload is greatly reduced; under the method provided by the invention, the experimental workload required for an oil saturation interpretation method is reduced, and the experimental technical requirements are low (without rock electric experiments required by the Archie formula in a laboratory); the experimental cost is reduced; and the method is suitable for true resistivity and each gradient resistivity, has simplified workload, and has great technical potential and economic value in the interpretation of the saturation of the tight reservoir.

Description

technical field [0001] The invention belongs to the field of logging interpretation methods for tight sandstone reservoirs, in particular to a method for improving the interpretation accuracy of oil saturation in tight sandstone reservoirs. Background technique [0002] The oil saturation interpretation of tight sandstone reservoirs is related to the accuracy of reserve calculation, and at the same time has a direct guiding effect on production construction in high oil-bearing belts. In domestic and foreign studies on oil saturation interpretation of clastic rock reservoirs, the Archie formula, as a classic method, has been widely used in many oil reservoirs, and it is involved in the calculation of exploration reserves and the secondary interpretation of oil layers. [1,2] . The a, b, m, and n parameters involved in the formation factor F and the resistance increase rate I in this formula are very important to the interpretation accuracy. The precision of the parameters th...

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Problems solved by technology

From the publication of the Archie formula to the present, the research on rock electricity based on the model has not stopped, which has created a new era for the application of rock electricity research and electrical logging data in oil and gas reservoir evaluation, but the existing problems cannot be ignored: Al Odd used rock samples with high porosity and high permeability, which is no longer valid for rocks with low porosity

In addition, Archie's formula does not consider the influence of mud, and experiments have proved that the existence of clay minerals makes the electrical conductivity mechanism of rocks extremely complicated, and Archie's formula is invalid for freshwater-saturated sandstones with very low salinity.

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