The unconformity surface in the Permian of Junggar basin and the characters of oil-gas migration and accumulation

There are many unconformity surfaces in Permian system of Junggar basin, which are very important for oil and gas to migrate with long-distance and in great-scale and to accumulate. Seismic section comprehensively interpreted to discover that patterns of unconformity sections in the Permian include fold unconformity, fault-fold unconformity, truncation unconformity, onlap unconformity and parallel unconformity. Each of them has the different distributing regularities in basin, and the type of unconformity surface controls oil and gas migration along it. On the basis of analyzing log responses and cores, the unconformity surfaces in vertices are divided into three parts: under-conglomerate, weathering claystone and paleokarst zone, this structure forms the double paths of the oil and gas migration. It connects reservoirs and faults which formed in different times to construct the regional migrating network. The unconformity surfaces in the Permian of Junggar basin not only are the important paths for the oil and gas migration, but also are the good places for the oil and gas accumulation. Undersurfaces can form reservoirs which are covered by the unconformity surfaces, and upsides can form lithologic reservoirs characterized by stratum onlapping.