Developments in Hydrocarbon Fluids for High-Temperature Fracturing

Fracture stimulation using liquid hydrocarbon fluids such as crude oils, condensates, and refined oils has been a common practice since the first fracturing treatment was performed. However, until recently the use of a hydrocarbon fluid for proppant transport in treatments where the fluid is exposed to temperatures exceeding 225/sup 0/F (107/sup 0/C) has been limited by fluid viscosity instability. This problem has been magnified by restrictions on the maximum fluid viscosity which can be conveniently and safely handled and pumped on the surface. A fracturing process is described wherein viscosity stabilizing additives are incorporated in a hydrocarbon fluid to provide adequate viscosity stability at elevated temperatures. The process utilizes a combination of chemicals which serve to initially thicken (gel) the hydrocarbon fluid on the surface, and a delayed thickener which provides additional viscosity down hole during the fracturing operation. These additives provide excellent frictional drag reduction in tubular conductors and, therefore, reduce friction pressure and horsepower requirements to perform the fracturing treatment. A theoretical discussion of the chemicals required to perform the fracturing operation is included. (13 refs.)