Method for predicting pad-acid-fracturing crack flow conductivity distribution of carbonate rock

Abstract

The invention relates to a method for predicting pad-acid-fracturing crack flow conductivity distribution of carbonate rock. The method comprises steps as follows: a pad-acid-fracturing process is divided into a fracturing crack making period and an acid injection period, a crack extension process of the fracturing crack making period is simulated by adopting a two-dimensional PKN crack extensionmodel, and crack length, crack width and pressure p0 in the crack when the fracturing crack making period t1 is ended are obtained; in the acid injection period t2, t2 is equally divided into n time steps, and concentration of acid liquor in the crack, acid-corroded crack width and flowing pressure p1 of acid liquor in the crack in the crack length direction when the first time step is ended are obtained; the concentration of acid liquor in the crack, the acid-corroded crack width and the flowing pressure pj (j=1,2,3,...,n) of acid liquor in the crack when any time step in the acid injection period t2 is ended are obtained; fracture flow conductivity distribution wkf after the pad-acid-fracturing crack is closed is calculated. With the adoption of the method, the flow conductivity distribution of the acid-corroded crack in the crack length direction can be accurately predicted, the pad-acid-fracturing design scheme of the carbonate rock is optimized, and the development effect of the carbonate rock is improved.

Description

technical field [0001] The invention relates to the field of acidizing and fracturing reservoir reconstruction for oil and gas field development, in particular to a method for predicting the distribution of fluid conductivity of carbonate rock pre-fluid acid fracturing fractures. [0002] technical background [0003] Carbonate reservoir is an important reservoir of oil and gas resources and has great potential for development. Carbonate reservoirs are mainly composed of limestone and dolomite, and the burial depth is generally more than 5000m (Qi Baoquan, Zhao Zuoan, He Hongju, et al. Using the comprehensive evaluation index of well logging reservoir quality to judge the effectiveness of reservoirs—a case study in the Sichuan Basin An example of Permian Qixia Formation in western China[J]. Natural Gas Industry, 2018, 38(02): 25-32). This type of reservoir has low porosity, permeability and strong heterogeneity, and it is difficult to exploit oil and gas resources under natu...

AI Technical Summary

Problems solved by technology

The indoor core experiment method is the most intuitive and simple way to obtain the fracture conductivity, but the disadvantage is that it is difficult to predict the fracture conductivity in the real formation environment, and is limited by the size of the experimental core sample, so it is impossible to obtain the fracture conductivity along the fracture length direction. Distribution of real diversion capacity

The fracture conductivity calculated according to the empirical formula is more widely used and easier to realize, but there are often certain errors

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