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Sequence-based Lithofacies Paleogeography And Favorable Facies Belt Of Reservoir Prediction Of Early Cambrian Longwangmiaoan Age In Guizhou Area

Posted on:2017-03-22Degree:MasterType:Thesis
Country:ChinaCandidate:B S ZhengFull Text:PDF
GTID:2180330482984098Subject:Mineralogy, petrology, ore deposits
Abstract/Summary:PDF Full Text Request
Longwangmiaoan Stage is one of the most important gas production horizons in the Middle and Upper Yangtze area. Based on lithologic microfacies, sedimentary facies and carbon and oxygen stable isotope stratigraphic research, the Lower Cambrian Longwangmiaoan Qingxudong Formation can be divided into two third-order sequences in Guizhou area which lies in the west side of Taijiang-Majiang line, it is sequence 1 and sequence 2, respectively, and both can be subdivided into transgressive system tract and highstand system tract. The sequence boundary between sequence 1 and the underlayer and the one that between sequence 1 and sequence 2 are both facies change surfaces, no exposure characteristics can be found, so they are correlative conformities, but in many places exposure characteristics can be found at the sequence boundary which lies at the top of sequence 2, so it is an exposure unconformity, which indicates that intense regressive progradation happened during the highstand of sequence 2. In the transitional facies area, like Danzhai area, there is just one third-order sequence can be recognized, which also can be subdivided into transgressive system tract and highstand system tract. In the basin facies area, like Sandu area and the more southeastern area, it is a condensed succession consist of carbonaceous shale which is hard to dicern and divide the third-order sequences. Based on the construction of sequence stratigraphic framework, the sequence-based lithofacies paleogeographic maps of all the four system tracts were drawn, and these four maps shows the same facies belts distribution characteristic, that is, from northwestern Guizhou to southeastern Guizhou, inner ramp facies belt, middle ramp facies belt, outer ramp facies belt and basin facies belt are distributed sequentially, and at the interior and the margin of the inner ramps, shoals, which is the favorable facies belt of reservoir, with different sizes can be found. Based on the sequence-based lithofacies paleogeographic maps, abdominal area distributed between the Wuchuan—Xishui—Renhuai—Dafang line and the Songtao—Zhenyuan —Wengan —Xiuwen—Puding line is pointed out as the prospective areas of favorable facies belt of reservoir, and the abdominal areas at this two lines are the preferential exploration targets. Finally, combine the sedimentary characteristics of all sections with the facies belts distribution characteristics on the sequence-based lithofacies paleogeographic maps, the depositional model of Longwangmiaoan of Guizhou area should be carbonate ramp.
Keywords/Search Tags:Guizhou area, Longwangmiaoan Stage, sequence-based lithofacies paleogeographic map, favorable facies belt of reservoir, depositional model
PDF Full Text Request
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