Acid fracturing simulation method considering dynamic process of variable-viscosity acid

Abstract

The invention discloses an acid fracturing simulation method considering a dynamic process of variable viscosity acid. The method comprises the following steps of: respectively measuring the relationship between the viscosity of the variable-viscosity acid and a shearing rate, temperature, calcium ion concentration, a pH value and surfactant concentration and establishing a variable-viscosity constitutive equation, simulating the flowing and reaction process of the variable-viscosity acid liquid in a fracture system to obtain a pressure profile in the fracture system, simulating and calculating the reaction process of the variable-viscosity acid in a matrix by taking the pressure profile in the fracture system as an inner boundary condition and the ground pressure as an outer boundary condition, simulating the viscosity change condition of the acid liquid in the matrix system and calculating to obtain the filtration speed, and bringing the obtained filtration speed into the pressure profile in the fracture system in the step. The method is used for solving the problem that in the prior art, the acid fracturing simulation technology does not consider the dynamic filtration process of the variable-viscosity acid, so that the coincidence rate of the variable-viscosity acid fracturing simulation fracture length and the actual situation is not high, and the purpose that the acid fracturing fracture form considering the dynamic reduction rate of the variable-viscosity acid can be obtained through simulation is achieved.

Description

technical field [0001] The invention relates to the field of fracturing, in particular to an acid fracturing simulation method considering the dynamic process of viscous acid. Background technique [0002] Viscosity acid is a variable-viscosity acid fluid first synthesized by Schlumberger in 1997. It is used in fracturing fluids for oil and gas stimulation through hydraulic fracturing and acidification. There are a large number of old oil fields abroad. Production capacity, successful application of new oilfields to increase recoverable reserves. The initial viscosity of the existing viscose acid is 170 -1 The shear rate can be about 30mpa·s. With the reaction of the acid liquid and the formation matrix, the pH value increases. When the pH value rises to about 2, the viscosity of the acid liquid system rises sharply and can reach 1000mpa·s. Then, as the acid-rock reaction continues, when the pH value reaches about 4, another chemical reaction is triggered to reduce the vis...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a kind of acid fracturing simulation method considering the dynamic process of viscous acid, to solve the acid fracturing simulation technology in the prior art that does not consider the dynamic filtration process of viscous acid, resulting in the length of the simulated seam length of viscous acid fracturing In order to achieve the purpose of simulating the shape of acid fracturing fractures after considering the dynamic drop rate of viscous acid due to the fact that the rate of agreement with the actual situation is not high

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