Study On Sedimentary Microfacies Of Member X8-S1 In The Western Of Block Su75 Of Sulige Aera

Block Su75 is located in the northwest side of Sulige gas field,the Erdos basin Yishan slope northern of middle belt in structure.Although the braided river sedimentary background,sand body development,but the lack of unified classification method of small layer in the region,the reservoir development phase change fast,resulting in reservoir are scattered and difficult to predict.Therefore,a new theory and method of the Block Su75 need to guide the next step of oil exploration and development.In this paper,taking Sulige Block 75 west of Shanxi Formation S1 Member and Shihezi Formation X8 Member as the research object,the use of sequence stratigraphy,sedimentology,petroleumgeology,geophysics and other theories,combined with regional geological data,core,cutting logging,well logging and seismic data,on the basis of previous work,study of sedimentaty micro phase were studied in detail,reveal the control function of reservoir development of gas bearing characteristics,mainly achieved the following results:1.By using the theory of sequence stratigraphy,determine the Member of X8 five small layer,a three layer of Member S1 division and correlation scheme,eventually established are search area of small layer contrast frame.2.The use of the divided data wells X8,S1 eight small layer,through the compilation of each layer thickness isoline map can be seen: the small thickness changes to some extent,this compared with the fluvial facies sedimentary characteristics;while the overall thickness of both the X8 Member and the S1 Member is the same,which reflects the sedimentary background the overall features of the Ordos basin.3.Through the sandstone thickness and sand ratio contour map,they all show from down to up and sandstone thickness and sand ratio characteristics of synchronous reduction,reflects the positive prosodic features Member X8 from the side,further proof that the work area Member X8 for the river facies;and the sandstone thickness and Sand ratio contour map each layer than the chart displays from lower to upper sandstone thickness increases with the sand ratio feature large stable,from the side of member X8 anti prosodic features a section,further proof that the work area S1 member for a period of delta facies.4.Project objective layer mainly developed braided river depositional system,member S1 as the braided river delta plain subfacies,microfacies are mainly braided channel,abandoned channel fill deposit,overbank deposition;Member X8 composed of braided river facies,subfacies have river subphase and river facies,can be further subdivided into the channel bar,channel lag deposit,crevasse splay and flood plain facies.5.The fine description of core characteristics analysis shows that: the river sedimentatry system of the microfacies combination to determine the developmental characteristics of Member X8 reservoir sandstone,and the advantage and the development of reservoirs directly controls the gas bearing characteristics,The coring wells containing gas of the main reason lies in the difference of reservoir development.