Study On Depositional System Of2^nd Member Of The Shawan Formation In Chunguang Block Of Junggar Basin

Junggar Basin is rich in oil and gas,the Chepaizi area is located at the northwestof the Junggar Basin,and Chepaizi area is so adjacent to oil-generating sag, buriedshallow, a long period of hydrocarbon migration and favorable point to area, makesthe petroleum geological condition is very superior.In early2005, along with the pai2Wells had yield industrial oil flows, to get a high yield of shawan formation of "oilwindow" started the seismic attribute technology for shallow reservoir explorationdevelopment boom, after pai2well breakthrough, pai8well、pai206well、pai2-80welland pai2-86well are successively won the oil flow, etc. However,pai9well、pai10well and pai11well,etc,drilling in Shawan layer,is defeat.It’s making Shawanreservoir exploration at a low ebb. Therefore, it is necessary for the block liningsequence stratigraphic framework and depositional systems, source direction andsedimentary facies belt distribution characteristics of intensive study.According to the above problem, based on the sequence stratigraphy, seismicstratigraphy and sedimentology of theoretical guidance, using waveform analysis,seismic scans, layer equality method, Comprehensive seismic, drilling and loggingdata,to study Chunguang area in shawan formation of sequence stratigraphicframework and depositional system analysis and research of the system. The mainachievements are:1) By analyzing the values of the velocity from sand shale velocity in our studyarea, Buried depth is very shallow(700-2000m).which include: Ⅰtype, the velocity ofsand is slower than the mud stone(Delta, Deep-water fan); Ⅱtype, the velocity of sandis about the same as mud stone(Delta plain); Ⅲt ype, the velocity of sand is faster thanthe mud stone.2) On the basis of waveform analysis, the results of seismic reservoir acousticvelocity greater than the speed of sound, light oil with a gas-bearing strata of thehighlights of the seismic response. Highlights a strong response not only depends onthe amplitude, but also depends on whether they have right tilt symmetrical waveform,where the reservoir characteristics of the ground are the most important high-amplitude reflection.3) Using of the T-R sequence mode, the Shawan formation is divided into threesequences:SQ1、SQ2、SQ3, that were correspond to the N1s1, N1s2, N1s3segmentsof Shawan.4)To select3roughly along the source direction and over a vertical well section2source direction and do layer flattering process to restore the sedimentary strata ofshape,building Shawan Sec of sequence stratigraphic frame mode.5）With sand group or paragraph a basic unit, according to the shape, internalstructure, amplitude, frequency seismic attributes, seismic facies analysis. Shawanformation of seismic facies types mainly include: clean strong amplitude reflection,weak amplitude reflection, reflection amplitude of clean, moundy reflection, weak inblank reflection amplitude.6）Use of waveform analysis to identify technology，with5x5to explain sandbody in the study area, Depict the N1S21sand body distribution, analysis thesedimentary system Within the sequence stratigraphic framework, combining with thedepositional environment. Believes that the braided river delta and Deep-water fan isdevelopment in study area. Provenance comes from the early stage of the northwestand northeast in the late.