A Cost-Effective Oilfield Brine Treatment Technology

Abstract

SPE Members Abstract Stripper wells generally produce formation brine along with oil. In order to meet the discharge criteria established by federal and state environmental agencies, and to sustain continued production from these marginally economic wells, this brine must be treated in a cost-effective manner. This paper presents the research efforts leading to such a technology Introduction The oil and gas industry in the Appalachian Basin, which encompasses the states of Kentucky, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia, is primarily composed of hundreds of independent small businesses. Normally all wells operated by these independents are classified as "stripper wells" in that the daily producing capacity of a well does not exceed 10 barrels of oil, or 60 MSCF of gas per day. For example, the Independent Petroleum Association of America indicated that in 1989 Appalachian oil producers operated 101,274 oil wells (16.8% of the total number of operating domestic wells) while only producing 21,626,000 barrels of oil (an average of 0.585 bbl/day/well), less than one percent of the country's total 1989 production. Likewise, Appalachian gas producers operated 117,243 gas wells (approximately 45% of the total number of operating gas wells in the United States) while only producing 650,342 MMSCF (an average of 15.20 MSCF/day/well), or approximately 3.6% of the total volumes of natural gas produced in this country. Because of the large number of wells needed to produce such low volumes of hydrocarbons, operators of these wells conduct business on the basis of very thin profit margins. The thin profit margins associated with this production make it extremely sensitive to increases in operating costs or decreases in prices paid for their commodity. Appalachian Basin oil and gas wells typically produce small volumes of brine. As many as 87% of the primary stripper oil wells throughout the region produce less than one barrel of brine per day. Stripper gas wells operating in the Appalachian Basin produce even less with 97% of these wells producing less than one barrel of brine per day. Oil and gas brines have been identified as a potential source of environmental degradation, and each oil well site where brines are produced is a potential candidate for regulatory control under the U.S. Environmental Protection Agency's National Pollutant Discharge Elimination System (NPDES) permitting program. Presently, brine produced by gas wells are ineligible for this program; only stripper oil well brine discharges are exempt from the Clean Water Act's zero-discharge effluent guideline, and operators may treat and discharge brine into surface streams under this regulatory programs. In addition, in some states, independent producers are also subject to separate state permit programs designed to address identical issues. In Pennsylvania, for example, oil well operators may use the stream discharge option for brine disposal if they are able to satisfy the NPDES permit requirements of the Clean Water Act as implemented in the Pennsylvania Department of Environmental Resources (DER) Part I permit process and the Part II Water Quality permit requirements of the state's Clean Streams Law. P. 35^