Fracturing Fluid Interactions With Formation Minerals and Their Subsequent Effect on Formation Permeability

Abstract

ABSTRACT The selection process of hydraulic fracturing fluids for oil and gas well stimulation applications largely ignores interactions of the stimulation filtrate and the broken stimulation fluid with formation minerals. Fluid interactions with formation minerals may have a significant influence on formation permeability and subsequent well production. Laboratory formation core regain permeability studies, subsequent to the injection of both low and high pH fluids, were conducted to measure fluid effect on core permeability. Results of these tests indicate that both the rock mineralogy and the pore system morphology are affected by contact of the rock with filtrate from the injection of an unbroken stimulation system into the formation. Formation permeability after treatment with stimulation fluid can be significantly influenced by formation-injection fluid interactions. Studies have demonstrated that, depending on the specific formation mineralogy, post-injection permeability may be increased by low pH systems only, by high pH systems only, or by either low or high pH systems. The focus of this paper is to identify specific formation minerals which may potentially be affected by contact with fracturing fluid filtrate and broken fracturing fluid and to relate increases in formation permeability to resultant fluid-rock interactions. Mechanisms of fluid-formation interactions and chemical reactions are presented.