Tectonic Evolution Of Southwestern Sichuan And Its Effect On The Accumulation Of Oil And Gas In The Three Permian Series

Sichuan basin is located in the northwest of the Yangtze block, is in the upper Yangtze craton on the development experience of oil and gas rich multi stage evolution of the superimposed basin. The Cenozoic tectonic evolution stage is mainly affected by the North China plate, Southern China plate and collision control after the intracontinental subduction of the Cenozoic tectonic since evolution is mainly affected by the peripheral orogenic belt uplift. Southwest Sichuan is the interaction between the two areas most strongly, the multi stage evolution and multi stage tectonic movements resulted in the complexity of reservoir basin oil and gas accumulation. Koupo group of oil and gas exploration in Sichuan basin in Triassic Lei three for half a century, many scholars from the structure, sedimentation, reservoir has done a lot of work features of the reservoir and the Leikoupo reservoir, however due to the geological background and sedimentary palaeogeographic sedimentary in three middle Triassic Leikoupo Formation of complex difference Different, resulting in the Sichuan Basin in Triassic thunder mouth slope group palaeogeomorphology distribution characteristics and reservoir sedimentary characteristics of main control factors, the oil and gas into reservoir process progress is weak. In Triassic mine slope mouth group exploration in Sichuan, Northwest Sichuan, Western Sichuan depression were found. However, in the Dragon Gate Mountain in the southern area of southwestern Sichuan Province no breakthrough, visible the Leikoupo Formation of oil and gas into reservoir complexity. Therefore, based on tectonic evolution of southwestern Sichuan Province are studied in detail, analysis of the Middle Triassic thunder mouth slope group paleo tectonic pattern, sedimentary characteristics has important significance.This study is mainly based on the field geological survey of the route, sediment profile measurement, logging data analysis and two-dimensional seismic interpretation, restored in the Southwest area of tectonic characteristics and evolution process, to explore its tectonic evolution of the control effect of Leikoupo Formation of oil and gas accumulation. It is suggested that the thrust nappe formed in tectonic characteristics the southern section of Longmen mountains in southwest Sichuan basin and Longmen mountain orogenic, closely related. According to the deformation and strength of structure in the area of basin mountain structure, direction and fracture characteristics in Leikoupo structure as the main basis, the structure of the study area is divided into units of Longmen mountain piedmont fault fold tectonic belt, Mingshan syncline Chengdu sag Dihuan tectonic belt, Xiongpo-Longquan mountain fault fold tectonic belt, Emei Mountain-Washan fault fold structural belt. Southwest Sichuan from piedmont tectonic characteristics towards the basin in the basement involved type imbricate structure and fault related folds. Tectonic deformation style in Southwest Sichuan from Longmen to the southern segment of Longquan mountain tectonic belt (from west to East) was three. The basement involved with imbricate thrust belt, fault related fold thrust belt and triangle zone. In the southwest area of structural features in addition to the Yangtze plate itself from southeast to northwest of the pushing force and the Qinghai Tibet Plateau from the west to the east of the pushing force of joint control, a more important factor is the most important internal cover slip layer is three lower Triassic internal salt rock, control the vertical deformation characteristics of structure, the vertical stratification was the upper continental strata thrust tectonic system characteristics of tectonic zone, the lower part of the marine strata into distinct roof type imbricate structure. Southwest Sichuan tectonic evolution is divided into pre Indosinian tectonic movement caused great depression alternate tectonic evolution of Dalong Indosinian basin lifting show, inherited uplift tectonic evolution of Yanshan period, many episodic uplift formed in Longquan Shanxi uplift tectonic framework and depression, the Himalayan strong fold uplift in four stages. Southwest Sichuan Leikoupo Formation only local hydrocarbon generating conditions, no large-scale accumulation ability, the major source rocks overlying Ma'antang-Xiaotangzi and lower Permian in Southwest Sichuan. Tectonic evolution showed that early Triassic formed three underwater Luzhou uplift, control of ancient the sedimentary tectonic pattern in Southwest Sichuan Lei koupo group before the Indosinian period, inherited palaeohighs, control group of Lei sedimentary slope facies, Yanshan period and Himalayan period is mainly reformed and destroyed the structure.