Method for determining cave volume in stratum

Abstract

The invention discloses a method for determining cave volume in a stratum. The method comprises the following steps of: establishing a fractured-vug type oil reservoir well testing model, and taking akarst cave in the stratum as a point source; according to the fractured-vug type oil reservoir well testing model, adopting a superposition principle to obtain a real space well bottom pressure solution obtained when a plurality of karst caves are simultaneously in the presence in the stratum; utilizing the real space well bottom pressure solution obtained when the plurality of karst caves are simultaneously in the presence and well bottom pressure data which is actually measured to carry out fitting, and according to a fitting result, determining a dimensionless distance between a second karst cave and a first karst cave; and according to the dimensionless distance between the second karst cave and the first karst cave, determining a dimensionless reserving coefficient of the second karst cave, and according to the dimensionless reserving coefficient of the second karst cave, determining the volume of the second karst cave. According to the method, an assorted explanation method is provided for the reservoir stratum parameter calculation and the reserve calculation of a fractured-vug type oil reservoir, the volume and the distance of the karst caves in the fractured-vug type oilreservoir as well as a provided flow ratio can be directly explained, and technical support is provided for formulating an oil field development scheme.

Description

technical field [0001] The invention relates to the technical field of oil and gas exploration and development, in particular to a method for determining the volume of a cave in a formation. Background technique [0002] The matrix of carbonate fracture-cavity reservoirs basically contains no oil, and the storage spaces are mainly fractures and caves. The flow of crude oil in fractures and caves has pipe flow and seepage. When crude oil flows in deep fractures and caves, the vertical flow is obvious. At present, there are two theories of triple medium and equipotential body in well test interpretation methods for fracture-cavity reservoirs. [0003] The triple medium theory divides the oil storage space of fracture-vuggy reservoirs into vugs, fractures and matrix. Among them, the matrix is ​​the main oil storage space. The fractures are directly connected to the wellbore, the caves supply fluid to the fractures, and the matrix supplies fluids to the fractures and caves. B...

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Problems solved by technology

[0005] At present, these two theories are based on conventional well test interpretation theory, and the results based on conventional well test interpretation are parameters such as permeability, storage capacity ratio and channeling coefficient, which are only among the parameters of fractures, matrix and caves in the formation. The average value of , using these parameters can not recognize the characteristics of fractures and caves, and can not determine the volume parameters of fractures and caves

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