This development document presents the technical data base development by EPA to support proposed effluent limitations guidelines and standards for the Offshore Subcategory of the Oil and Gas Extraction Point Source Category. Technologies covered by the document to achieve these limitations and standards are defined as best available technology economically achievable (BAT) and best conventional pollutant control technology (BCT) for existing sources, and best available demonstrated technology (BADT) for new sources. Best practicable control technology currently available (BPT) effluent limitation guidelines for this industry segment were promulgated on April 13, 1979 (44 FR 22069). BPT guidelines are addressed in this document only to the extent that they serve as a baseline for the development of BAT and BCT effluent limitations guidelines and new source performance standards (NSPS). The bases for BPT can be found in an earlier development document (EPA 440/76-005-a). This document outlines the technology options considered and the rationale for selection of the technology levels on which effluent limitations and standards are based.