Comparison of Evaporite-Related Source Rocks and Implications for Petroleum Exploration: A Case Study of the Dongying Depression, Bohai Bay Basin, Eastern China

The Dongying Depression (Bohai Bay Basin, eastern China) was widely filled with evaporite (anhydrite and halite) layers during the Paleogene period, especially middle of fourth member Shahejie Formation (Es4). Most are interbedded mudstone strata. strata Es4 divided into three sections, referred to as upper layers, lower respectively. analysis elemental concentrations, ratios, Pr/Ph suggests that were deposited in an intermittent saline lake environment within a relatively dry climate. formed highly environment, whereas brackish-saline fresh-water environment. Organic matter (OM) abundance indices, including total organic carbon (TOC), chloroform extracts, hydrocarbon content (HC), generation potential (S1 + S2), OM type, show source rock for petroleum is best, fair, it poor. Carbon isotopes (δ13C) hydrocarbons heavier than those layers. Thermal maturity parameters thermal evolution process faster where present compared evaporite-free areas, while slower these regions. high conductivity evaporites may have accelerated rocks allowed at shallower burial depth. This resulted earlier appearance window areas. Meanwhile, restrained, consequently widened, which implies exploration deep under sequence. common phenomenon evaporite-bearing basins, according previous studies.