A Research On Volcanic Lithofacies And Characteristics Of Volcanic Reservoir Of Yingcheng Formation, Xujiaweizi Fault Depression, Songliao Basin

In recent years, the reaserch on Yingcheng Formation volcanic rock lithofacies and reservoir distribution characteristics increasingly become the focus of the study as gas-bearing fields being constantly found in deep volcanic zones. Volcanic rocks in the Cretaceous Yingcheng Formation are the main research target in Xujiaweizi area. Volcanic eruption pattern, petrology and Petrological characteristics ,lithofacies and spatial and distributions, The type and characteristics of reservoir space, the relationship of volcanic rock lithofacies and Reservoir ,and parameters controlling the reservoir quality are studied in this paper. Based upon the description and observation of drilling hole, identification of blue epoxy resin-impregnated thin section ,individual well facies analysis stratigraphic classification and comparison, seismic interpretation data. The prospecting high quality reservoir area is being assessed, based on the above integrated research work.Through this study,6 new congitions and conclusions are acquired: 1.Volcanic eruption model is mainly crack eruption controlled by faults,central eruption is secondely in Xujiaweizi area.2. The majority of the colcanic lithology is acid rock,secondly is neutral rock. the volcanicalastic and lava are the majority type of rock. The acid rock mainly contain rhyolite and volcanic breccia and volcanic tuff.3. There are mainly 5 kinds of facies in this area: volcanic channel facies, flushout facies, eruption facies, overflow facies,volcanic sedimentary facies. eruption facies and overflow facies is the mainly facies. The dominant reservoir space are the developed in the top of the overflow facies and the volcanic breccia of the eruption facies.4. The facies belt is controlled by Shengxi fault and Songxi fault strike direction is north west-southeast,the eruption center is near fault,outward are eruption facies- overflow facies-volcanic sedimentary facies.5.primary space,induced space and compound space are the main types of the reservoir space in Xujiaweizi area. Primary space contains air cavity and residual pore in amygdaloid, intergranular pore and contract seam. induced space contains dissolved pore in feldspar and quartz and structure seam. compound space contains dissolved- intergranular expanding pore, intragranular-intergranular dissolved expanding pore.6.The reservoir’s capability basically depend an the lithology and facies of volcanic,tectonic movement and fault’ affection, the influence of diagenesis and fluid medium and weathering.