THE EVOLUTION OF SALTWATER DISPOSAL PRACTICES IN THE FORT WORTH AND DELAWARE BASINS OF TEXAS AND NEW MEXICO, USA

Earthquake activity in Texas has been increasing from its background historical rate since 2008, and saltwater disposal activity is implicated directly for seismic activity. If federal regulation and monitoring of underground injection began in 1982, and underground injection began well before then, why would associated seismicity not occur until 2008? This presentation helps answer that question, discussing the evolution of saltwater practices in the two regions of primary concern in Texas: the Fort Worth and Delaware basins. This presentation will discuss how saltwater disposal practices vary over time as functions of subsurface capacity, technology, state regulatory environments, and hazard. Subsurface target formations are mapped within geologic systems. Technological improvements are shown to sequentially improve economic and logistical efficiencies in both disposal and production, with unexpected impacts on the target formations. Lateral well development, economic impacts of production, and the computer evolution have impacted state regulatory practices for underground injection. More recently, the observation of earthquakes and potential for more has led to both operator and state reconsiderations. All are discussed in a series of time-lapse diagrams, volumetrics, surface maps, and geological interpretations made by the Texnet Center for Integrated Seismicity Research (CISR) at the University of Texas Bureau of Economic Geology.