Subsurface Brine Disposal – Be Reasonablea

Abstract

ABSTRACTA classical battle between landowners desiring to protect their fresh ground water from pollution and oil companies needing a disposal zone for injection of oil‐field brines developed in Texas County, Oklahoma.Initial studies showed that the disposal zone (Glorieta Formation) was in places only 500 feet below the bottom of the fresh‐water aquifer (Ogallala Formation). Furthermore, solution/collapse features in the intervening formations plus numerous poorly plugged wells and exploration holes provided potential avenues of brine migration. The potential for pollution appeared very real. The landowners not only wanted to halt construction of new brine disposal wells, but also wanted all 33 existing disposal wells abandoned and plugged. Tempers flared and intermittent litigation continued for over two years.A more complete hydrogeologic analysis led to the following observations: (a) the potentiometric surface in the Glorieta is 100 to 400 feet below the water table in the Ogallala in areas where brine disposal is taking place; and (b) the transmissivities of the Glorieta and disposal rates are such that even pressure gradients around disposal wells are below the water level in the Ogallala. These hydrologic facts led to the conclusion that, even with a perfectly open conduit connecting the two formations, migration of disposal brine from the Glorieta into the fresh‐water Ogallala would be impossible in the critical area because of pressure relationships.Techniques using “pressure bombs” and test injection data are presented by which transmissivity values in the Glorieta were estimated. Disposal well design and completion methods used by the oil companies were found to be inefficient and contributed to operational problems. Specific regulations were adopted regarding disposal wells to further assure that pollution of the Ogallala would not occur.As a result of all parties understanding the hydro‐geologic factors, the oil companies are continuing to use the Glorieta as a disposal zone and the fearful landowners are assured that no real pollution hazard exists. This outcome assures full use of all natural resources–which is true conservationism. Ground‐water technicians not only have a responsibility to use and protect ground‐water resources, but also to assure that unnecessary cost burdens are not placed on other industries in the name of pollution prevention.