Prediction Of Reef Reservoir In Changxing Formation Of Longgang West Area

This paper studies the characteristics and distributions of strata, deposition and reservoir of Changxing formation in west of Longgangxi area based on outcrop, drilling, logging and seismic data utilizing principles of seismic stratigraphy, carbonate sedimentology, seismic sedimentology, seismic geomorphology by a macro-micro combined approach. This study recognize the seismic reflection characteristics of reef utilizing seismic forward modeling; depict distribution of sedimentary facies in Changing formation under the control of sedimentary paleogeomorphology; study characteristics of reef reservoir by seismic forward modeling; predict reservoir distribution characteristics by the technology of impedance inversion. The results showed that Changxing formation can be divided into two sections, and it changes to Dalong formation from southwest to northeast. The difference of stratum thickness is obvious, but it can be traced contrast in the whole area. Changxing formation includes several kinds of subfacies:open platform, platform margin, slope and ocean trough. The platform margin can be divided into platform edge reef, grain bank, interbank sea, interreef waterway and interreef lagoon. We can recognize five seismic facies in this area and the reef seismic face has the characteristics of mounded reflection and disordered reflection. The reef is distributed along both directions between northwest and northeast. The belt extended northwest located in the northwest has several rows. The reservoir which developed in the top of reef is mainly dolomite and has typical character of seismic highlight reflection. Reservoir thickness develops from20meters to100meters and distributes along both northwest and northwest.