Hazim Abass

Hydraulic Fracturing: Experimental Modeling

Abstract Since the beginning of hydraulic fracturing, many modeling efforts have been made to understand the operation on all disciplines related to the process such as reservoir engineering, fluid mechanics, rock mechanics, material science, and chemistry. This chapter presents the experimental modeling, which was the first tool to understand hydraulic fracturing. The process of hydraulic fracturing requires understanding near-wellbore phenomena to make an engineering design for a stimulation treatment. Experimental modeling lends itself to such applications where a small-scale testing reasonably provides insight on how a fracture initiates and propagates from a circular hole. Rock samples obtained from outcrops or synthetic samples may be used to understand the effect of a wellbore and near-wellbore stress field on a fracture geometry generated from hydraulically pressurizing the well until a tensile failure occurs. There are distinct features associated with any rock formation such as homogeneous or heterogeneous, brittle or ductile, consolidated or unconsolidated, permeable or tight, and intact or naturally fractured. These features significantly affect hydraulic fracturing results that can be modeled in laboratory scale testing. The primary logical difference between fracture stimulation of conventional versus unconventional reservoirs is that in conventional reservoirs a fracture is introduced for the hydrocarbon to sense and flow toward it; whereas in unconventional reservoirs, a fracture is created to reach where the hydrocarbon is located. In this chapter, first fundamental experimental modeling in hydraulic fracturing is presented, which provides an understanding of the principles of hydraulic fracturing propagation pattern. Then, more recent and advanced experimental models are provided, which include fracturing fluid interaction with the rock at pore scale and recent advances in creating large fractures using less water or eliminating water.