Estimating Depth and Producing Formations of Abandoned Oil and Gas Wells Using Geospatial Analysis

Abstract:

More than three million abandoned oil and gas wells exist in the U.S., and information on many of these wells are lost. Recent measurements of 93 abandoned wells in Pennsylvania show that they may be a significant source of methane emissions to the atmosphere. Data such as depth and producing formation of 98% of these measured wells are unavailable. Information on the likely depth of the well and the formation, from which the well likely produced from, is important when evaluating the wells’ potential to emit methane and/or to contaminate overlying aquifers, and when developing mitigation strategies. We use geospatial analysis that combines available public databases from the Pennsylvania Department of Environmental Protection and historic documents to determine the likely depth and formation from which the measured abandoned wells produced. We develop a framework to systematically evaluate the nearest well, pool, and field attributes and assign depth and producing formation to the measured wells based on how well these attributes match. We then use this information to perform a cost analysis for plugging based on well depth for Pennsylvania. The geospatial analysis framework presented here for determining abandoned well properties can be valuable for future field measurement designs, upscaling methane emissions, and mitigating abandoned wells in Pennsylvania but also the many other states with a long history of oil and gas production.