Sequence Stratigraphy And Sedimentary Facies Of The Lower Triassic Jialingjiang Formation In The Middle Segment Of The Western

Middle segment of Longmen mountain lies in the western Sichuan basin and its area is about8000km2. In resent years the oil and gas reserviors mostly lies in Continental strata of Mesozoic-Cenozoic. Adjacent to the east Sichuan, Northeast Sichuan massive reef-phase reservoir and the nation’s largest marine gas field-Puguang gas field discovery, the basic signals in the same sedimentary and tectonic setting of western Sichuan region Permian-Middle Triassic with enormous oil and gas exploration potential. However it is almost not find oil and gas. What is the main causation movement or sedimentary facies? Study of fracture is already very mature, So we should study particularly the sedimentary facies of the whole area of Middle segment of Longmen mountain. So that we can rebuilt ancient geography and ancient environment to guide the direction of oil and gas exploration. Article adopting the theory of sequence stratigraphy and combining the seismic, drilling and outcrop data, taking the third-order as the emphases, designates the sequence of Lower-Triassic Jialingjiang Formation, of middle segment of Longmen mountain. I designed two third-order sequences(SQ1to SQ2),4-5tracks which have been particularly described. Based on the stratigraphic delinetion, I made the cross-correlation of the sequence of well/outcrop and main seismic section, build the sequence stratigraphic trellis of basin and select main line to study its seismic facies. Taking third-sequences and tracks as the cell of drawing picture, taking outside configuration, inside shape and physics parameters as the element of drawing picture.I drew the maps of first-fourth segments of Lower-Triassic Jialingjiang Formation and drew sedimentary facies according that seismic facies match sediment facies. The main sedimentary face is wide platform. I forecasted the favorite reservoirs of middle segment of Longmen mountain in western Sichuan basin by studying sedimentary facies. We drew a conclusion that Lower-Triassic Jialingjiang Formation of western Sichuan basin lacks favorite reservoir but second and third segments of Lower-Triassic Jialingjiang Formation develops the reef and beach sedimention which can be take as favorite reservoir belt. I suggest we should particularly study the formational sequences of middle segment of Longmen mountain in the future in order to open up the good phase of the depth exploration.