Sequence Stratigraphy And Reservoir Analysis Of Silurian And Lower Kepingtage Formation Of Ordovician In Western Manjiaer Depression, Tarim Basin

According to the classical sequence stratigraphy theory of passive continent margin which was brought forward by Vail etc, this thesis analyzed the detailed sequence of Silurian and the lower Kepingtage Formation of Ordovician, Western Manjiaer Depression, Tarim Basin, found the sequence framework of whole region and researched on high resolution sequence of the lower Kepingtage Formation. Then, the thesis carefully analyzed the sedimentary facies of six key wells in the research area, educed the type of sedimentary system of whole research region, researched on sedimentary micro-facies connecting with the result of high resolution sequence of the lower Kepingtage Formation. Last, the thesis researched on the characters of sandstone reservoirs, emphasized on oil cutting sandstone of the lower Kepingtage Formation.First, on the basis of collecting drilling wells, well logging, outcrops, seismic and palaeontological data, synthetically using many data divided the sequence, confirmed the type of sequence and system tract. The thesis divided the Silurian and the lower Kepingtage Formation into two second-order sequences, the Kepingtage Formation was the first second-order sequence, the other was the other sequence, also divided the research region into six third-order sequences, and each third-order sequence divided into system tracts, the sixth third-order sequence divided into the lowstand system tract (LST) and the transgressive system tract (TST), the other sequences divided into the transgressive system tract (TST) and the highstand system tract (HST).The thesis identified three depositional systems of Silurian and the lower Kepingtage Formation in the research region: clastic shoreline, offshore shelf and deep water basin, and clastic tidal flat depositional systems. These depositional systems not only differentiated with sedimentary and palaeontological characterization, but also differentiated in evolution regularity of plain and vertical sedimentary system. The foreshore and shoreface sub-facies were recognized in the clastic shoreline sedimentary system in the research region. The intertidal sand-mud flat and sub-tidal sand flat sub-facies of clastic tidal sedimentary system can be recognized in the lower Kepingtage Formation of well Jinan1.The types of rock of Silurian and the lower Kepingtage Formation in the research region are mainly mid-fine grain lithic sandstone and mid-fine grain quartz sandstone, in which the rocks'composition and texture maturity was high. The combination of pore type in sandstone reservoir was intergranular dissolved pore, granule dissolved pore and micro-pore. The influence factor on reservoir characterization was depositional environment, burial depth and the distribution of clay minerals.