Oil and gas reservoir well testing interpretation model and method based on karst cave point source equivalence principle

Abstract

The invention discloses an oil and gas reservoir well testing interpretation model and an oil and gas reservoir well testing interpretation method based on a karst cave point source equivalence principle. The method comprises the following steps of S1, establishing a karst cave point source equivalent radial oil and gas reservoir well testing physical model; S2, establishing a mathematical model of seepage of the production well in the double-medium stratum and solving the mathematical model; S3, establishing a mathematical model that the karst cave is equivalent to the injection well; S4, conducting simultaneous solving operation on the equivalent injection well and production well mathematical model, and drawing a well bottom pressure and pressure derivative double logarithmic typical well testing curve; and S5, fitting the typical well testing curve of the well bottom pressure and the pressure derivative with the actually measured well bottom pressure and pressure derivative curve,and explaining stratum parameters. According to the method, a karst cave point source equivalent radial well testing model is established for a radial oil and gas reservoir with large karst caves in discrete distribution, continuously-developed natural micro-cracks and corrosion dissolved holes in the oil and gas reservoir are regarded as double continuous media. The large karst caves are equivalent to discrete distribution variable-strength point sources, and the radial oil and gas reservoir karst cave point source equivalent radial well testing model is established.

Description

technical field [0001] The invention relates to the technical field of geological exploration, in particular to an oil and gas reservoir well test interpretation model and method based on the equivalent principle of karst cave point sources. Background technique [0002] Carbonate reservoirs have unbalanced development of fractures and caves, strong heterogeneity, complex types of reservoirs, and diverse storage spaces. According to different types of reservoirs, it can be divided into four types: fracture type, fracture-dissolved pore type, fracture-dissolved cave type and dissolved pore-fracture-dissolved cave type reservoir. Fracture-cavity reservoirs in which fractures and caves develop simultaneously are an important type of reservoirs. Fracture-cavity reservoirs represented by the Tahe Oilfield in the Tarim Basin in my country account for more than 30% of the total carbonate reservoirs. , and is also an important branch field for increasing reserves and production of c...

AI Technical Summary

Problems solved by technology

For the well test model of this type of reservoir, due to the existence of discrete large caves, it is impossible to establish a seepage model based on the continuum theory. Therefore, most of these reservoirs are calculated by equivalent models or numerical simulation methods. The error is large, the latter is difficult to model, and the amount of calculation is large

For example, the classic continuous dual-media model proposed by Warren and Root[2] and domestic and foreign scholars have proposed various well testing models and drawn corresponding well testing theory charts after decades of research, but most of these well testing theories are based on continuum Assumptions, the continuity assumption of this type of well test model is not fully applicable to fracture-cavity reservoirs with large scale and discrete distribution of fractures and caves, and the well test chart of the continuum model is often difficult to fit the field measured curves of fracture-cavity reservoirs , and cannot explain the parameters of large-scale fractures and large caves

In recent years, on the basis of discontinuous media, some scholars have successfully explained the parameters of fractures and caves by establishing well testing models such as well drilling encountering karst caves and combination of fractures and caves in series and parallel. Limited, cannot be applied to reservoirs with more fracture-cavity combinations

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