Migration of Hydraulic Fracturing Fluids by Deep-Well Disposal into Fresh-Water Aquifers
Wednesday, April 26, 2017: 9:10 a.m.
Ronald Green, Ph.D., P.G.
,
Geosciences and Engineering Division, Southwest Research Institute, San Antonio, TX
F. Paul Bertetti, P.G.
,
Geosciences and Engineering Division, Southwest Research Institute, San Antonio, TX
Deep-well injection is the most common means of disposal of hydraulic fracturing flowback and produced water. While usually environmentally safe when conducted at appropriate locations and depths using acceptable deep-well disposal technology, fresh-water aquifers can be adversely impacted if the injection horizon is not capable of safely storing the fluids or if injection practices are inadequate. Because many shale gas and tight sand hydrocarbon fields are located at or near conventional oil/gas fields, spent oil/gas formations are often targeted for deep-well disposal due to relatively high permeability and under-pressurization. Risks to safe containment in the injection horizon are encountered, however, when the isolation capacity of the injection horizon is compromised by existing boreholes and wells that were not effectively plugged and abandoned, or if the injection well is not properly constructed, maintained, and monitored. Evaluation of current deep-well disposal practices in the Eagle Ford and Permian Basin has shed light on what factors need to be addressed to be able to adequately assess whether a disposal well will pose unacceptable risks to fresh-water aquifers. Examples of risk assessments due to over-pressurization of injection horizons, improperly plugged and abandoned boreholes and wells, and improperly constructed injection wells are discussed.
Ronald Green, Ph.D., P.G., Geosciences and Engineering Division, Southwest Research Institute, San Antonio, TX
Dr. Ronald Green is an Institute Scientist in the Geosciences and Engineering Division at Southwest Research Institute in San Antonio, Texas where he has worked for the past 25 years. His primary activities are in groundwater hydrology and environmental geophysics. Recent work has focused on water availability in south-central and west Texas and the impact of oil and gas activities on water resources. Of particular interest are the water resources of karst limestone aquifers including assessments of recharge, characterization of flow mechanisms, and numerical modeling. Dr. Green is a Fellow in the Geological Society of America and is certified as a Professional Geologist in Texas. He holds a B.S. in Industrial Engineering from the University of Michigan, a B.S. in Geology from Grand Valley State University, a M.S. in Geophysics from the University of Utah, and a Ph.D. in Hydrology from the University of Arizona.
F. Paul Bertetti, P.G., Geosciences and Engineering Division, Southwest Research Institute, San Antonio, TX
F. Paul Bertetti is a principal scientist in geochemistry at the Geosciences and Engineering Division, Southwest Research Institute® in San Antonio, Texas. Mr. Bertetti conducts field and experimental investigations to evaluate and understand the relationships between the aqueous geochemistry and hydrology of the subsurface. He has used hydrochemical data and modeling in numerous studies to characterize flow, recharge, and interconnectivity of several major aquifers, including the Edwards, Edwards-Trinity, and Carrizo-Wilcox aquifers in south Texas. Mr. Bertetti also conducts field, laboratory, and modeling studies to examine the sorption and ion-exchange behavior of dissolved radionuclides and other inorganic constituents.
