A Research on the Techniques for Identifying Lithologic Stratigraphic Traps in the Southwest 3D Survey of Chaidamu Basin

摘要

The Southwest Chaidamu 3D survey is located between Kunlun and Aerjinmountains in the south region of west Chaidamu basin, which had been proved to beone of the most promising areas in this basin. The survey area is situated at the edgeof the Basin. The sand bodies originated from Kunlun and Aerjin mountains are goodfor forming various kinds of lithologic stratigraphic traps. Nevertheless, the thinnessof oil-baring layers, severe facies change and the weak seismic or sonic responsescharacterized by this area are the geological factors that hinder the exploration oflithologic stratigraphic reserviors. And what is more, the lack of effective geophysicaltechniques and systematical research strategy is one of the most important reasons. Aiming at the geological characteristics and the current exploration situation inthe Southwest Chaidamu 3D survey area, lithologic stratigraphic reservioridentification and analysis work was conducted. During the research, thecontemporary tectonics and tectonic evolution had been studied to analyze arelationship between tectonics activity and lithologic traps fonm and development. The study of palaeo-structure not only provide the foundation for thestratigraphic sequence model building and, systems tract deposition model divisionand the establishment of facies classification, but importantly determine a favorablezone for the identification of lithologic and stratigraphic traps. An isochronous stratigraphic framework was established through the study ofsequence stratigraphy in the study area. The sequence developing at Tertiary in studyarea was divided into three Ⅱ sequences and sevenⅢsequences. Several favorablelithologic stratigraphic zones had been found and determined variable traps to makeclearly next research. Different sedimentary facies types had been found through studying sedimentaryfacies. The various cycles of reservoirs distribution and reservoirs nature had beendetermined and then provided evidence for finding high quality good reservoir. The identification techniques and methods had been studied for lithologicstratigraphic traps to establish models of identification and analysis for SouthwestChaidamu Basin exploration basing on geophysical analysis. And the better effect hadbeen obtained in practice. The targets had been optimized to provide drilling suggestion basing onfavorable zones and lithostratigraphic traps evaluation. The better effect and economiceffect had been achieved through drilling. Several innovations had been obtained through studying the project. 1 the theory and methods of