Sedimentary Facies Of The Tertiary In West Qaidam Basin

Integrating geology and geophysics, the observation and description of outcrop and drilling core, and through the analysis of single factor with synthesize factor drawing, the article studies sedimentary facies and its space distribution in Tertiary in West Qaidam Basin, recover its sedimentary evolution history and distribution. The change of the hydrocarbon resource centre in macroscopic aspects, at the same time, the most prospective sandstone bodies were forecast.Firstly, based on the observation and description of a large number of drilling cores in macroscopic and microcosmic aspects, facies marks are summarised, which supplied from the characteristics of lithology, distribution of grain size, sedimentary structvure, ichnology and logging facies.Secondly, through the identification of facies marks and the analysis of sedimentary facies cross sections, alluvial fan, river, fan delta, delta, lake, sublacustrine fan and tempestite sediment environment have been developed in West Chaidam Basin. Alluvial fan develops in the front of Altun slope. Fan delta distributes in the west of Altun slope. Delta develops in Yunjin, Dongchaishan, Huangshi and Dafengshan area. River distributes widely in Gasikule, Niubiziliang area. In the other place, lake develops.Thirdly, based on the study of cross sections, the article sets up sedimentary framework in the area by correlation six sedimentary facies cross sections.Aaccording to the principle of gravel depth contour diagrams, sandstone depth contour diagrams, percentage of gravel contour diagrams, percentage of sandstone contour diagrams and method of quantificational sedimentary facies, The distribution and evolution of sedimentary facies have been summarized, and meanwhile the paleogeography been recovered for Tertiary formation in West Qaidam Basin.Lastly, the article analyzes the situation of sedimentary center and its transferring regularity based on mudstone color-zoning's characteristic, developing situation of shallow-deep lake and deep lake, forecasts the promising sandstone reservoirs by integrating analysis of tectonic setting and physical characteristics of sandstone bodies.