The Study Of Silurian Sedimentation Feature And Regularities Of Sand Body Distribution In Tazhong Area

Tazhong area is located in the central Tarim Basin, the structure is located in theTazhong Low Uplif of the eastern central uplift zone among Tarim Basin, thestructural position between Tanggubazi depression, Bachu uplift and Guchengxuuplift, the north of this aera is slope zone which be in connection with the Manjiardepression. This paper set KEPINGTAGE formation of palaezoic Silurian as targetlayer.According to the present situation of exploration in Tazhong area, consideringthe existing problems, placeing the sedimentary facies research as the Center for thestudy, using sedimentology, mineralogy, logging geology, petroleum geology,structural geology, seismic stratigraphy and other multi-disciplinary knowledgesynthetically, combining with the results of previous studies, geochemicalexamination of samples rocks, drill core observation, and rock thin slice observation,identify the sedimentary subfacies and microfacies sedimentary sequence of targetlayer. In this paper, by means of geophysical logging method identification of the rockelectricity relation feature, divides sedimentary subfacies and microfacies，studies thesedimentary evolution of the KEPINGTAGE formation in the the three sub section, toreveal the sedimentary evolution and sedimentary facies distribution ofKEPINGTAGE formation. Based on area distribution of sedimentary facies and singlewell sand body vertical distribution feature, using the seismic stratigraphy, comparesseismic attributes of3D seismic data, recognizes distribution of sand body.According to the lithologic features, sedimentary characteristics, characteristicsof grain size and well logging facies such sedimentary facies, studys sedimentaryfacies of Silurian KEPINGTAGE formation. Tazhong area of KEPINGTAGEformation mainly grow clastic non-barrier clastic sedimentary, which located from theeastern slope to the northwest southeast with zonal distribution features. TZ16wellarea developed shore shallow lake and shallow marine deposits in southeastern area.Evolution of Silurian sedimentary influenced by the tectonic subsidence andsea-level change. The major effect of tectonic movement of Silurian deposits ofmiddle Caledonian movement at last stage of the Late Ordovician/Silurian period,the late Caledonian movement in the late Silurian, Early Hercynian movement in thelate Devonian period.Changes of sea level have some influence on the deposition of Silurian inTazhong. Sea level changes and structure subsidence combined effects on Silurian sedimentary presented in the following aspects:1. Silurian bottom surface and the topsurface appear uplift unconformity and regional unconformity surface;2.Thedistribution of sedimentary facies of the control effect of relative sea-level change.Silurian KEPINGTAGE formation sedimentary mainly growth tidal flat faciessubtidal faces, intertidal and supratidal facies, sand body distribution controled bysedimentary facies distribution.Based on the regional3D seismic data of the KEPINGTAGE formation’s top andbottom interface as time window boundary, extract seismic attributes, intersect withsingle well sand thickness data, select the RMS amplitude attribute to recognizedistribution characteristics of sand body, and the result is reflected in area distributionof sedimentary facies.