Influence of diapir structure on formation and distribution of overpressure in the Yinggehai Basin, South China Sea

The Yinggehai Basin (YGH) in the South China Sea is a Cenozoic, high-temperature, and high-pressure basin. Exploration development of natural gas resources YGH show that owing to diapir structures make formation pressure system complex, overpressure characteristics are obvious, prediction difficult, spatial distribution irregular, which severely restricts gas. To evaluate influence on overpressure, we compared analyzed ancient modern geothermal temperatures, organic matter maturity, clay mineral evolution, burial depth, coefficient nondiapir zones YGH. results showed occurred following order: Uplift–spiking–piercing–depositing. Dongfang area dominated by low-amplitude turtle-back with weak energy, whereas Ledong high-amplitude spiked strong both pressurize upper formation. Changnan pierced/depositing diapirs can relieve pressure. its associated be attributed transport body fault-fracture local thermal effect caused upwelling hot fluids. Under structure, top surface basin was shallower. According degree intensity variations depth divided into four evolution modes: constant pressure, slow pressurization, “Z” “S” pressurization types. This study provides some guidance references for identification accurate mechanism basins containing diapirs, helps formulating efficient drilling production plans.