Exploration of Lithologic Traps in Block D in the South Turgai Basin

Block D in the South Turgai Basin is located in the gentle slope zone of the faulted lake basin, where only a few faults are developed and mainly located in the Lower Jurassic and the structural traps are undeveloped, so it is important for explorers to find lithologic traps. Existing drilling results show that Jurassic lithologic traps contain mainly two types: updip pinch-out sand at front of slope zone and isolated sand body in underwater distributary channels. Combining with the three-dimensional automatic interpretation technology based on the stratigraphic framework model and sequence stratigraphy analysis technology, it is considered that the Middle Jurassic in the slope zone of block D is delta and fan delta facies deposits, which have the development conditions of lithologic traps. The distribution characteristics of sand bodies in the Middle Jurassic slope zone are described by seismic forward modeling and facies-controlled geostatistical inversion techniques. Comprehensive analysis of hydrocarbon accumulation conditions shows that effective reservoir-seal assemblage is the main controlling factor in the study area, and favorable lithologic traps are mainly distributed in the upward dip direction of slope zone.