RESERVOIR CHARACTERISTICS AND CONTROLLING FACTORS OF SHA 1 MEMBER IN MIAOBEI AREA, EAST BOHAI BAY

The reservoir of sha 1 Member in the Miaobei area has been proven by logging to be a reservoir with poor physical properties. If there is high quality reservoir remains a question in decision making for further exploration. Base on side-cores, thin sections, and seismic, logging and testing data, we made a thorough study on reservoir properties and their influencing factors, and discussed the possible existence of high-quality reservoirs and their distribution in this paper. Data Shows that the reservoir in Sha 1 Member is low in porosity, and low to very low in permeability. The reservoir space is provided mainly by dissolved pores between and/or within grains. Carbonate cementation under alkaline water conditions, facies at the edge of a fan delta and diagenetic transformation of illite in clay minerals are the factors leading to poor reservoir properties. Dissolution is believed the major factor for improvement of reservoir quality. Therefore, reservoirs with better quality may occur in some places with favorable microfacies, strong dissolution and extraordinary high pressure conditions, such as the main channel of fan deltas at the lower wall of a syndepositional fault and carbonate banks at depositional highs.