Study On The Tectonic And Sedimentary Facies Of The Alishan Formation And The Tengger Formation In The Beibiao Formation Of The Bayinduan Depression

Combined with the previous studies on the study area, using the well logging data, logging data, drill core,3D seismic data, test oil data, the Geological structure analysis theory of depression basin, geophysics and sedimentology to study the structural feature and sedimentary facies of the Tenggeer formation and Aershan formation in the north trough of the Bayindulan depression.The stratum in the study area is divided into Aershan formation, lower sub-member of member1of Tenggeer Formation, upper sub-member of member1of Tenggeer Formation and lower sub-member of member2of Tenggeer Formation. First of all, the synthetic seismogram is made by velocity logging data to calibrate horizons. Secondly, the coherent body and horizontal slice are used to interpretate structural feature. The To diagrams of interface of target stratums are converted into deep tectonic maps by the time depth coversion. Through a detailed structural analysis, the faults can be divided into2categories. The first formation is the main faults which developed very long time. These faults are general North-South extension. Another team is the smaller faults that are general East-west extension. The role of these faults is to further complicate the step-fault zone and slope to form a range of fault-block and faulted nose structures which provide space for the oil and gas. The Aershan formation’structural activities were violent, and developed many main faults. Structural activities in Tengyi member began to abate slightly. To the time of Tenger member, the settlement activities weakened significantly, but the range of deposition enlarged obviously. After the time of the member1of Tenggeer Formation, the North, South, low-lying high of the tectonic framework of the study area changed. From the time, the study area became the low amplitude of monoclinic structure.In the study of sedimentary facies, combined with the regional geologic background, drilling data, logging data, drill core and the3-D seismic data, the target stratum is studied. Lake facies, turbidite fan, fan delta are identified. These micro-facies are detailedly described.Fan delta and shore shallow lake are mainly developed in Aershan formation. To the lower submember of member1of Tenggeer Formation, semi-deep lake and shore shallow lake are mainly developed because of the rapid rise of the lake level. Because the lake level relatively declined in the upper sub-member of member1of Tenggeer Formation, nearshore subaqueous fans were developed in the bold shore zone while turbidite fans were developed in the gentle slope zone. In the lower sub-member of member2of Tenggeer Formation, the lake basin further withered, so the pro-graded fans were developed.Based on the above results of the study of structure and sedimentary facies, the oil test data and the reservoir forming laws, the favorable zones are forecasted and2proposed wells location are confirmed.