A seven-year thermal project in "old Wilmington" field (Los Angeles basin) for the "Tar zone" is part of a technology-transfer program by the United States Department of Energy (U.S. DOE) which proposes to transfer successful new techniques to other oil and gas producers operating reservoirs comprised by sediments exhibiting similar conditions of heterogeneity and depositional environment. The present form and structural relief of the Los Angeles basin were established during late Miocene time. Most of the area consisted of marine slope-to-basin environments during late Miocene and early Pliocene time. The basin is divided into four structural blocks with major zones of faulting in the basement rocks at the contacts between blocks. The fault systems bounding the blocks have allowed each block to have a different subsidence history and basement configuration.