A Stimulation Technique Using Only Nitrogen

Nitrogen alone has demonstrated success as a fracturing fluid in reservoirs normally found sensitive to liquid systems. It has proven useful in shales of the Ohio Valley and West Virginia areas, and in similar lithology of the Fort Worth Basin located in North Central Texas. The fracturing efficiency of nitrogen, as related to leakoff and flow capacity testing with no propping agent, has been investigated to analyze the effectiveness of nitrogen stimulation. Also, field data are presented which demonstrate successful results of the nitrogen technique in both oil and gas reservoirs. From the laboratory studies and field results, several conclusions were drawn concerning nitrogen stimulation. Of primary interest is that most of the width reduction in an unpropped fracture will occur in the early stage of production which indicates a sharp decline of the well flow rate after a relatively short period.