Pressure transient testing and stimulation treatment programs are presented for four development/exploratory wells located in the Sand Dunes Field in Wyoming’s Powder River Basin. While pressure buildup tests conducted during initial completion yielded relatively high permeabilities and severe skin for all but the initial well, core analyses yielded much lower permeabilities and suggested low susceptibility to damage. The core data were discounted, and the buildup test data were relied upon to design small hydraulic fracture treatments to overcome suspected near-wellbore damage. As a result of the treatments, significant increases in productivity occurred which verified the buildup interpretation.
For all four wells, stimulation treatment data and pre-and post-stimulation buildup test analyses are presented. Application of the pressure derivative analysis technique is demonstrated. Through comparison of pressure responses in damaged and improved systems, qualitative as well as conventional quantitative transient test analysis techniques are presented.
The utility of pressure buildup testing for identifying stimulation candidates and providing reliable fracture design data is illustrated. Relying on core data in this field would have resulted in inappropriately designed, less cost-effective hydraulic fracture treatments, and serious underestimation of production potential. The effectiveness of small hydraulic fracturing treatments designed solely to penetrate extremely high skin is demonstrated.