Prediction Of The Bioreef Facies Reservoir Of The Changxing Formation In The LG47 Well Area In Eastern Sichuan

Carbonate biological reefs,the favorite gathering place for oil and natural gas,is a kind of carbonate rock structure built by organisms,also the main type of oil-bearing gas deposition in carbonate sedimentary.It has a prospective oil-bearing gas potential.Reefs are widespread not only throughout the world,but also throughout China,they are a vital part of oil and gas reservoir in carbonate reservoir.The Changxing biological reef in LG,East Sichuan area,is studied in this paper.The area is the major gas reservoir in marine carbonate reservoir in Sichuan basin.It has unique oil and gas reservoir and high porosity and permeability,but complex geological conditions of reef reservoirs which causes the exploration difficult.The research on prediction technology of favorable facies zone of reefs is of great importance in guiding the exploration and production of reef reservoirs.The study combined the cores observation,thin section examination,SEM and physical property analysis with previous exploration and development data especially the drilling,logging,mud logging and seismic information,attribute to the reef favorable facies dividing and the layers analyzing.Meanwhile,extending outward from the typical reefs wells,we restore wells with the lithologic seismic response pattern.The physical characteristics and seismic response characteristics of carbonate reefs are summarized and analyzed,also the pattern of reef seismic interpretation is grasped.At last,under the guidance of sedimentary facies research,special techniques such as oil-field impedance inversion and reservoir quantitative prediction are adopted to identify the development scope of reef reservoirs.And the distribution graph of thickness,porosity and the maps of storage factor are drawn.With the application of the above methods,the distribution scope of the reefs of LG47 well zone and the favorable distribution zone of the reservoir can be predicted.The explanation of 3 reefs,total 37.81km2,in the Changxing formation provides evidence of the new round of drilling distribution and enhances the success rate of drilling.