Application of an area of review variance methodology to the San Juan Basin of New Mexico

When the Underground Injection Control (UIC) Regulations were promulgated in 1980, existing Class II Injection wells operating at the time were excluded from Area of Review (AOR) requirements. EPA has expressed its intent to revise the regulations to include the requirement for AOR's for such wells, but it is expected that oil and gas producing states will be allowed to adopt a variance strategy for these wells. An AOR variance methodology has been developed under sponsorship of the American Petroleum institute 1 . The general concept of the variance methodology is a systematic evaluation of basic variance criteria that were agreed to by a Federal Advisory Committee. These criteria include absence of USDWs, lack of positive flow potential from the petroleum reservoir into the overlying USDWs, mitigating geological factors, and other evidence. The AOR variance methodology has been applied to oilfields in the San Juan Basin, New Mexico. This paper details results of these analyses, particularly with respect to the opportunity for variance for injection fields in the San Juan Basin.