West Slope Of Mahu Depression Tectonic Characteristics And Its Hydrocarbon Accumulation Studies Of The Northwestern Margin Of Junggar Basin

The research area was the West slope of Mahu depression of the northwestern margin of Junggar basin in this thesis, and the emphasis study layers were Permian Uroh group and Triassic Baikouquan group. We used the wild geological research, combined with drilling, logging data to strata division in Uerhe group and Baikouquan group. West Slope area was located in the foreland thrust belt of the northwestern margin of Junggar basin. And the tectonic evolution was controlled by Kramary-Bai fault and Uroh-Xia fault. Through the seismic inversion and combined with sedimentary facies research to analyzes the reservoir distribution area, and analyzes the the identify way of the hidden traps in this area. Emphasis focus on the hydrocarbon accumulation factors. Mainly achieved the following understanding:(?)(1) Western Slope of Mahu depression region layers unconformity contact were controlled by the tectonic, and mean the while angle unconformity were under the influenced of the foreland thrust belt of the northwestern margin of Junggar basin.The fault system in the study area was mainly controlled by Uroh-Xia fault and Kxamary-Bai fault, affected by the foreland thrust belt, the faults of the western slope zone mainly developed in the deep strata which under Baikouquan group, Reverse fault of Paleozoic could be divided into two periods.(2) Permian Urho group structure was appear south to east lean form,have develop block structure and nose structure in some areas. Triassic layers succession Urho group structural form, nd its tectonic force gradually decreases, reducing the structure margin.(3) Sedimentary facies of the Permian Urho group was fan delta front depositional system, and the top of it below the maximum flooding surface, and it forms the high quality reservoir, sedimentary facies of Triassic Baikouquan was alluvial fan-fan delta-shallow lake depositional system, and the lime stone of its top formed high quality trap. There are exist two source system:Xiazijie provenance systems and Huangyang springs provenance system.(4) Through the tectonic evolution characteristics, fault system distribution and unconformity reasearch, conclude that it will form fault structural traps in the western slope zone.combined with fault system and favorable sandstone sedimentary, it also easy to match fault-layer and fault-lithologic traps.(5) There three main factors controlled hydrocarbon accumulation in the western slope of Mahu depression:(1) fault system and unconformity block the hydrocarbon migration,(2)structural stress and pressure of traps for oil and gas aggregation,(3)differences of lithology to storage oil and gas.