HOW STRAY GAS ESCAPED DURING CONSTRUCTION OF AN OIL/GAS WELL, INVADED A WATER-SUPPLY AQUIFER, AND CAUSED AN IN-HOUSE EXPLOSION (Invited Presentation)
Construction of a structure-contour map on the top of the Berea Sandstone, the major aquifer tapped by residential wells, indicated that stray gas from the English #1 well would migrate northward in the sandstone, which is overlain by a highly-jointed shale, along a sloping surface into a dome-like structure that has a spillover point on its eastern edge. The temporal methane measurements made in residential wells confirmed this migration pattern. Borehole videos taken in several residential wells directly after the in-house explosion were repeated in 2008 and 2009. Comparison of videos made in the same wells showed the bottom of the (stray) gas cap migrated vertically out of the sandstone into the Cuyahoga Shale. Overpumping 16 nearby residential wells for up to 7 months augmented this natural attenuation of the stray gas. The upward movement of the gas cap indicated accidental overpressurizing of the annular space following a substandard cement job in the English #1 well did not create multiple networks of fractures connecting the Clinton Sandstone production zone with the Berea Sandstone aquifer, as alleged in the lawsuit. The upward movement of the gas cap also indicated that natural gas from the production zone would not act as a perpetual source of hazardous gas that could invade homes and water wells forever, as also alleged in the lawsuit.