ABSTRACT

The Underground Injection Control Regulations promulgated in 1980, under the Safe Drinking Water Act of 1974, require Area-of- Review (AOR) studies be conducted as part of the permitting process for newly drilled or converted Class II injection wells. A study was undertaken, with U.S. Department of Energy sponsorship, of the opportunity for AOR variances for injection wells in the Texas Gulf Coast Frio Formation oil producing trend.

In the course of this study, AOR variance opportunities were examined for 73 oilfields in nine Texas Gulf Coast counties. It is believed that the combination of well construction and abandonment characteristics plus the presence of sloughing and squeezing shales and porous and permeable sand sink zones provide for the possibility of AOR variances in 57 of the 73 study fields. The remaining 16 fields are ones where the oil accumulations occur in conjunction with shallow salt domes and where geologic conditions are probably too complex to allow field-wide AOR variances. The successful study results can probably be extended to at least 78 additional oil fields in 17 other Frio Formation producing trend counties. The full final report of the study described herein was submitted to the DOE in 1997 (Warner, et al., 1997).