Studies On Sedimentary Facies And Reservoir Characteristic Of He8 Section,eastern Sulige Gas Field Of Ordos Basin

Sulige gas field in Ordos Basin is one of the largest gas filed in China,the 8th section of lower shihezi formation (Permin) are the main gas-producting interval in the East Sulige gas filed.It is vital significant to detailde research on its sedimentary facies and reservoir characteristic for the next exploration and development.Based on predecessor's achievements,the research object of this thesis is He 8 formation,Using the theory of sedimentology,petroleum geology and geophysics,combined with regional geological data,core,flakes and logging data,we try to study the sedimentary facies of He 8 section. At the same time,detailly disccussed diagenesis and reservoir characteristic ,and the main results and understandings are follows:1.According to the clastic constituents statistics of 998 rock samples,using the principle of naming by triangle classification chart,in accordance with the difference of He 8 section are mainly in area of lithic quartz sandstone and lithic sandstone with the content of 52.2% and 40% separately,and the quartz sandstone is relative few,which accounts for 8.8%.2.Based on the sedimentary, geochemistry and electrofacies marks,alluvial fan sedimentary system in north and alluvial plain which mainly are made up of braided river and meandering river.Two fluvial sedimentary system have the transformation both in time and plane.Carrying out a detailed studying of sedimentary micro-facies in the depositional system,setting up a deposition model for it.3.Systemly studied petrologic characteristics,physical properties,pore type of He 8 formation reservoir sand ,and diagenesis which affec reservior according to physical parameters,,reservoir sand of porosity and permeability is positively correlated.By studing the porosity and permeability areal distribution region,there are obviously 3 bands of relatively high levels.sandstone reservior of study area mainly are especially low porosity and low permeability ones,secondarily are low porosity and low permeability ones, and few low porosity and low permeability, ones of especially low porosity and low permeability and middle porosity-middle permeability.4.The reservoir physical properties are mainly controlled by sendimentation, sedimentary fabrics,diagenesis,sedimentary facies and micro-facies will keep the distribution of effective reservoir and its thickness. Different sandstone types,fabrics have obviously effect on physical property.with the high content of quartz and coarse grain,the physical properties become better.The important diagenesis of sffecting reservoir quality is compaction,agglutination and dissolution. Some of them are destructive, some are constructive.