A Systematic Experimental Study of Acid Fracture Conductivity

Abstract

Summary The fracture conductivity created in the acid fracturing process is critical to the success of this stimulation method, but is difficult to predict. We have conducted a series of experiments in which core samples were acidized in a cell that allows for linear flow through a vertical fracture with fluid loss through the cores. The fracture conductivity created was then measured as a function of closure stress. We find that increased acid contact time sometimes results in lower fracture conductivity, fluid loss can increase fracture conductivity, and the Nierode-Kruk correlation1 accurately predicts the effects of rock embedment strength and closure stress on acid fracture conductivity. We also observed that high fracture conductivity is created when the acid forms a deep channel in the fracture.