Recent Advances In Carbon Dioxide Stimulation Technology

The technology associated with the use of carbon dioxide as a component of oilfield stimulation fluids has evolved dramatically since its introduction in the early 1960's. Technology improvements in the mechanical, chemical, and applications areas will be discussed herein. This paper will be introduced with a brief review of the chemical and physical properties of carbon dioxide which are the basis for the utilization of CO2, in the stimulation industry. The introduction will be followed by a discussion of mechanical advances in CO, pumping equipment, pressure maintenance devices, heaters, fluid viscosity measurement, flow monitoring instrumentation and safety equipment. Next, chemical developments such as CO,-compatible acid, water and alcohol gellants, dispersants, vapor phase stabilizers and crosslinkers will be traced. Finally, stimulation applications of CO2 will be described. These applications have multiplied from acid and hydraulic fracturing fluids energized by CO2 as a minor commingled component for rapid removal of mud, silts, fines, water blocks and emulsions, through miscible hydrocarbon treatments, to dispersions, "foams" and crosslinked alcoholic fracturing fluids where CO2 is the major component.