Recent Trends in Hydraulic Fracturing

Abstract

Abstract Trends in hydraulic fracturing over the years have closely followed an increased knowledge or better understanding of what occurs in the formation during a fracturing treatment. As more and more knowledge was gained emphasis shifted from materials to horsepower and high injection rates. Recently the shift has been back to materials and more careful planning and engineering of individual treatments. Improved technology within the past two or three years has led to the development of new, viscous fracturing fluids and more sophisticated computer programs. These developments have greatly improved results of fracturing treatments and have made it possible to successfully stimulate those wells which previously were poor candidates for hydraulic fracturing poor candidates for hydraulic fracturing treatments. The purpose of this paper is to discuss recent developments in fracture fluids and techniques and the technology involved in their use. Case histories are used to show the improvements in economy, efficiency, and increased production results. Introduction Since the introduction Hydraulic fracturing as a stimulation tool in the late 1940's, development trends have closely paralleled each fact learned concerning what actually takes place in a formation during a fracture treatment place in a formation during a fracture treatment In the early days, equipment available was capable of providing injection rates of one to two barrels per minute and screen-outs were common. It was felt that viscous fluids would suspend and transport propping agents better and development emphasis was on fracture fluids. Heavy refined oils became common frac fluids and water-in-oil emulsions, acid-in-oil emulsions, and soap-type oil gels appeared. Next, fluid loss was recognized and fluid loss agents were introduced. It was discovered that in many cases crude oil could be used as a fracture fluid with these new agents and treating economics apparently improved. The trend to crude oil with fluid loss agents, however, increased the incidence of screen-outs until a relationship between injection rates and screenouts was found. Increased injection rates reduced the probability of a screen-out and equipment was built to provide higher rates.