Sedimentology And Petroleum Geochemistry Study Of The Source Rocks In Jurassic Quse Formation And Buqu Formation, Biluocuo Region, Qiangtang Basin

Aiming at the source rocks in Jurassic Quse formation and Buqu formation in Biluocuo regionof Qiangtang basin, the thesis makes a study of sedimentology and petroleum geochemistry.Started with the sedimentary environment in which the organic matters generated, the thesis carriesout a systematic analysis research on the key sections of the Jurassic source rocks in Biluocuoregion of Qiangtang basin under the guidance of the theory of geotectology, sedimentology andpetroleum geochemistry. By combining microcosmic study with macroscopic study, fieldinvestigation with laboratory study, as well as analytical analogy with experimental analysis, thefollowing awareness and achievements has been get based on the previous research results.1. Analysis of sedimentary facies and sedimentary environment show that Quse formation isrestricted gulf sedimentary environment with its mainly sedimentary facies of lagoon tidal flat,while Buqu formation is open sea sedimentary environment with its mainly sedimentary facies ofacid salt gentle slope.2. Biomarker analysis show that the source of organic matters of Quse formation is a mixtureof lower aquatic phytoplankton, alga and certain terrestrial plants, while that of source rocks inBuqu formation is more concentrated as are mainly phytoplankton, and gamma wax alkaneanalysis show that the sedimentary water salinity of Buqu formation is higher than that of Quseformation.3. As in Quse formation, the average TOC of oil shale is9.23%, shale2.21%, and marlstone4.33%, they are all excellent source rocks; while in Buqu formation, the average TOC of pelmicriteis0.19%and marlstone0.1%, so they are relatively poor source rocks.4. The microstructure composition of Quse formation and Buqu formation are all mainlynon-definite sapropelinite composition (takes up more than70%)), which indicates that the organicmatters are mainly lower aquatic organisms in sea faces. As the inertinite content is over15%,which shows that certain higher plants are mixed in the organic matters.5. Kerogen carbon isotope test results show that as the carbon isotope of Quse formation andBuqu formation is between-28to-22with the average number around-26, it can bedetermined that they belong to kerogen type II2. According to the atomic ratios of elements, they are mixed type II as a whole, while Quse formation is more inclined to type II1and Buqu formationto type II2. The kerogen average type indexes of two formations are respectively45.53and63.7.The organic matters in the research area are mainly belongs to mixed type II.6. As the average vitrinite reflectance of the samples of Quse formation is0.99and that ofBuqu formation is0.9, both formations are in mature stage. The peak temperature range of Quseformation is in the mature range stage between430℃and560℃, while that of Buqu formation is inthe early stage of mature between498℃and512℃.7. According to the Van-Krevelen discriminant diagrams of H/C and O/C constitutions fromkerogen elemental analysis, the organic matters of both formations are in mature stage, and thematurity of organic matters of Quse formation is higher than that of Buqu formation.