High-Temperature Thermal Events and Diagenesis of the Reservoir of the Diapiric Structure Zone in Yinggehai Basin

In order to explore the relationship between the high-temperature thermal events and diagenesis of the diapiric structure zone in Yinggehai Basin,the authors regard the formation and evolution of the mud diapirs in Yinggehai Basin as the cutting point,analyze the basis and periodicities of high-temperature thermal fluid activities,and study the main diagenesis related with the high-temperature thermal fluid activities using the information such as sheets,probes,the compositions of formation water and gas,inclusion and so on.It is found that there are high temperature mineral assemblages,and calcium,magnesium ions in high salinity formation water,high carbon dioxide content of natural gas are richer than in diapiric structure zone.Paleo geothermal temperature of the inclusions is higher than today,and its distribution and fluid ingredients show that hydrothermal activities have periodicity.Compared with the non-diapiric zone,there is a high ion concentration of K⁺,Ca²⁺ and HCO^-₃ in formation water,which generated from dissolution of feldspar,carbonate and other substances,and a higher proportion of the secondary porosity such as feldspar dissolved pore,intergranular solution pore,mold holes and so on in the diapiric zone.The content of carbonate cement located near the diapiric area is high,in which the cementation is comparative developed.The study concludes that there are mainly three high-temperature thermal fluid activities in the mud diapirs,and the main diagenesis which related to high-temperature thermal event are dissolution and cementation.