Study On Permo-Carboniferous Sedimentary System In The East Of Linqing Depression

It has a better coal bed gas exploration prospects of Carboniferous-Permian coal bed measure strata in the east of Linqing depression. Under the guide of sedimentary theory, analogy mapping method is used to compile lithofacies paleogeography map. Within the stratigraphy framework of taking formation for unit, on the base of analyses of cores, well drilling ,well loggings ,and seismic data,it summarizes types of Permo-Carboniferous sedimentary facies in the study area,and studies on plane distribution characteristics and vertical evolutionary rule of the sedimentary system.. It mainly developes three major depositional systems,including barrier coast- platform compound sedimentary system, shallow water delta sedimentary system, meandering river deposition system and so on,including the platform facies, lagoon facies, tidal flat facies, barrier island facies, shallow water delta facies and fluvial facies and so on. It experienced epicontinental sea sedimentation--shallow water delta sedimentary-- umeandering river deposition evolution process in the studied area in Carboniferous-Permian. Lagoon and platform deposition are developed in benxi formation, the marine transgression during the this period happened in direction from sortheast toward northwest, open platform facies are mainly developed in the shenxian sag. Tidal flat,barrier island and lagoon deposition are developed in taiyuan formation, Barrier island sand takes the shape of the northeast-sorthwest distribution. Shallow water delta eposition are developed in shanxi formation,which mainly includes deltaic plain distributary channel and distributary interchannel deposit. Meandering river deposition are developed in shangshihezi and xiashihezi formation,main river bed takes the shape of nonth-sorth distribution. On the basis of the study deposition pattern are summarized in the studied area. To study the reservoir characteristics, it mainly clastic reservoirs in the Upper Paleozoic formation.,which belongs to low porosity and low permeability reservoirs. The pore structure is poor and the reservoir quality is bad. The main factors affecting reservoir quality are sediment and diagenesis . it shows that barrier bars facies in Taiyuan formation,deltaic plain distributary channel micro- facies in shanxi formation, deltaic plain distributary channel micro-facies in shanxi formation and river bed subphase in shangshihezi and xiashihezi formation are favourable reservoir facies in the study area. The effective reservoir sand in shangshihezi formation has the biggest thickness , the most shallow buried and the best petrophysical property.The reservoirs in shangshihezi formation distribution of the Upper Paleozoic is the most favorable reservoirs in studied area,which is an important objective of the exploration .