Control of the Basin-range Coupling Relationship Between Longmen Mountain Orogenic Belt and Western Sichuan Foreland Basin to Hydrocarbon Accumulation

According to the geochemistry,field section and well logging,the basin-range coupling relationship between Longmen Mountain orogenic belt and Western Sichuan foreland basin was explained,control of the coupling relationship to hydrocarbon accumulation was discussed,and some suggestion were put forward to exploration and predication of favorable area by means of petrology,stratigraphic correlation and basin modeling.The results showed that the basin-range coupling relationship,which included the correspondence of falling and uplift,that of provenance and sediment and that of tectonic multi-screen and sedimentary cycle,was good in terms of sediment and structure;the sedimentary coupling relationship controlled the sediment thickness and thermal evolution,and influenced the vertical and lateral distributions of reservoirs,but the tectonic coupling relationship had decisive effect on the development of faults in orogenic belt and foreland basin,and the traps for oil/gas migration and accumulation;the basin-range coupling was multi-phase,and the center of sediment and falling and the spread sedimentary facies were continuous migration and multi-overlay;there were three-dimensional screen evolution accumulation models in deep,middle and superficial layers in Western Sichuan foreland basin.The predication of favorable area showed that the southern part of Zitong Depression was the favourable region of deep basin gas;superficial layer gas distributed in the middle and southern parts of the basin developed by palaeohigh;deep layer gas mainly distributed in the pinchout zone of the northern and middle strata of the basin.