An Interpretation of Gasbuggy

Abstract

Preliminary post-shot results of the Gasbuggy nuclear detonation gave rise to speculation in the oil industry that the shot failed to achieve the extensive fracturing forecast for the technique. Basis for this speculation is that on re-entry 1 mo after detonation, an extrapolated pressure of 977 psia at the 4,150-ft datum was encountered in contrast with an anticipated 1,050 psia. Subsequent pressure buildup was very slow. Various considerations indicate that present limited gas production from the reservoir represents widespread areal recovery of gas from parts of the ultra-tight rock matrix immediately adjacent to the interconnected fracture system. The significance of the data in interpreting pressure observations in the re-entered Gasbuggy well is that higher pressure gas from previously undrained section in and adjacent to the 440-ft radius, 14-acre, nuclear fracture region not only is pressuring up the chimney, but also is recharging the native fractured zones that were more fully depleted by past production.