Meteoric Diagenesis Signatures and its Control on Fan Delta Siliciclastic and Lacustrine Carbonates Mixed Deposits Forming

Discovery of QHD29-2 and QHD36-3 oil field is the largest fan delta siliciclastic and lacustrine carbonate mixed deposits in Bohai Bay. The mixing zone exhibits distinct evidences of having been affected by meteoric waters. Petrographical evidences include intragranular pores, intragranular fissures, terrigenous kaolinite, vertical karst-fissures and gravitational cements and geopetal structure. Geophysical evidence shows that the ancient landform of the interest region is featured with a carbonate dome located on fan delta and volcanic basement. Geochemical evidence include laser micro-sampling analysis which shows values of δ18O with δ13C indicate meteoric or mixed water diagenesis, and fluid inclusion temperature of pedant cements indicating meteoric water environment. 4 types of carbonate cements are identified based on their occurrence and calculated temperature. Finally, the meteoric model of mixed deposits indicating diaganetic zonation is established.