A systematic experimental study of acid fracture conductivity

The fracture conductivity created in the acid fracturing process is critica l to the success of this stimulation method, but is difficult to predict. W e have conducted a series of experiments in which core samples were acidize d in a cell that allows for linear flow through a vertical fracture with fl uid loss through the cores. The fracture conductivity created was then meas ured as a function of closure stress. We find that increased acid contact t ime sometimes results in lower fracture conductivity, fluid loss can increa se fracture conductivity, and the Nierode-Kruk correlation(1) accurately pr edicts the effects of rock embedment strength and closure stress on acid fr acture conductivity. We also observed that high fracture conductivity is cr eated when the acid forms a deep channel in the fracture.