A method for predicting fracture conductivity based on three‐dimensional spatial morphology features

Abstract

Abstract The distribution of fracture clearance is an important factor that determines the conductivity of carbonate fractures. In this paper, the morphological analysis of acid fractures and the evaluation of acid fracture conductivity were carried out to test the characteristics of acid fracture clearance and the conductivity of acid fractures under the conditions of different acid rock reaction rates. Combined with the distribution rule of fracture clearance and the calculation formula of acid fracture conductivity under closure stress, the calculation formula of acid fracture conductivity of carbonate rocks is established and verified, and the influence rule of the distribution of fracture clearance on the conductivity of acid fractures is simulated and calculated. The results show that with the increase of the closure pressure, the conductivity of the fracture with a closure pressure of 60 MPa is about 94% lower than that of the fracture with a closure pressure of 10 MPa. The increase in acid dissolution rate is beneficial to improve the fracture conductivity under various closure stresses, and the acid dissolution is beneficial to reduce the influence of the closure stress on the fracture conductivity of acid dissolution. When the confining pressure is 10 MPa, the acid corrosion rate increases from 0.0001 to 0.0004 g/cm2 s, and the conductivity of the acid corrosion fracture increases from 27 to 420 μm2 cm. As the dissolution rate of acid solution increases, the proportion of large clearance on the fracture surface increases, the average value of total clearance increases, and the proportion of contact on the fracture surface decreases.

Keywords

• acid fracture
• carbonate rocks
• conductivity
• spatial morphology