| Sedimentary and reservoir characteristics of Changxing Organic reef in the east of KaiJiang-LiangPing trough are the research object.Guided by carbonate reservoir sedimentology & structural geology & diagenesis mechanism and forming mechanism,based on the previous research results,by means of the combined methods of indoor &ourdoor and outcrop & microscopy,drilling core and well logging data, the sequence and sedimentary facies, depositional environment impact on the reefs, reservoirs and reservoir control factors, characteristics of reef gas reservoirs have been studied, and the beneficial areas have been analysed.on the basis of the above .Studies suggest that tectonic activities are frequent in the east of Sichuan. In the early Permian, Hercynian sport make the Upper Yangtze Platform overall decline, in the region received the most extensive transgression, forming a shallow sea platform of sedimentary environment in Changxing formation. The sea level is rising most of the time during the period, the sequence is divided into the shelf margin systems tract, transgressive systems tract and highstand systems tract.Facies can be divided into restricted platform, open platform, platform margin reef facies, slope facies and trough facies. Multi-scale reefs develop at the slope break which lies between the open platform and clinothem facies in the time of transgression.Rreservoir of Changxing in the region has the reef limestone in the lower part and dolomite in the upper part, and dolomite reservoir is the best one. Reservoir development is controled by sedimentary facies, diagenesis and many other factors,overall, the reservoir in shelf edge reef is better than that in marginal bank, dolomitisation, dissolution, cataclasis and other diagenesis make the reservoir optimization,and reef dolomite is the best reservoir.Because of the good assemblage of source, reservoir, cap rock in the area, geological conditions of reservoir are favorable. Reef gas reservoir has dry gas with acidic gas, components to methane-based,no water in it. Type of reef gas reservoir is lithologic gas reservoir under tectonic settings, gas reservoir has strong heterogeneity, each reef has a separate pressure system. Reef and platform edge shallow facies is the most favorable facies for feef and reef reservoir development, seismic characteristics of reef is characterized by Mound-like structure, strong reflection amplitude, internal messy reflection, the reflection offset time between top and bottom of Changxing is large. |
