A review of over 400 fracture treatments in the Mesaverde formation of the Piceance Basin in Colorado indicated that use of low viscosity fluids resulted in decreased production. An extensive review of field results prompted Ely et al. to recommended a number of changes in the stimulation treatment, including the use of high viscosity fluids, reduced pad volumes, and aggressive proppant ramps with high concentration flushes.
An expensive fracturing study has been completed, evaluating over 400 fracture treatments on more than 130 Mesaverde gas wells in the Piceance Basin. This study involved a comparison of many types of fracturing fluids and techniques. Linear gels, foams, energized fluids, titanate crosslinked fluids, zirconium crosslinked fluids and borate crosslinked fluids have all been utilized in stimulating the Mesaverde formation in the study area. The authors evaluated the success of previous treatments which ultimately resulted in stimulation design changes, operational modifications, and expanded quality control methods. Dead strings were utilized on a number of treatments to record static tubing measurements and incorporate into a three dimensional (3D) fracture stimulation model. The modeling work assisted in determining fracture geometry which led to job size changes and revised perforating schemes. This paper will illustrate a number of correlations relating the effect of fracturing fluid viscosity, job size and completion method. Based upon the correlations of the study and the modeling work conducted, Barrett Resources has been able to greatly optimize their fracture treatments from the standpoint of cost effectiveness and enhancement of natural gas production.
Author(s): John W. Ely, Barrett Resources Corporation; Shawn D. Reed, The Western Company, Ely & Associates. Inc.; Ted D. Brown
Paper Number: SPE 29551