Petroleum Geology Study And Resource Evaluation In The Southeastern Depression Of The Tarim Basin

The southeastern depression is a main part of the Tarim Basin, and it is also a depression where less exploration has been conducted. With the rapid exploration and production in the basin, a great number of oil- and gas-fields have been found, some of whose regional geological settings are similar to those of the depression. This has drawn great interests from geoscientists in its further studies.Based on the geophysical, geological, logging, and geo-chemical data in solving the basic oil geology problems, this paper studies and evaluates the southeastern depression systematically by the use of geological and geophysical methods. The southeastern depression is strongly influenced by the tectonic movements from its surrounding structures, as it is located in the marginal strip of the Tarim basin. Judging from its growing history, we believe that the depression belongs to a piedmont overthrust of the foreland basin, and lies in the thick Cenozoic. Although less exploration has been conducted there, the finished work, in terms of acquired gravity, magnetic, electric, seismic sections, and acquisition samples, and logging data, provides us with valuable information, based on which we are able to comprehensively study and evaluate the depression.This paper starts with the gravity and magnetic data, and gets to know the depression's basement structure, fracture distribution, and regional structures. Then the paper fully studies its formation, fracture and evolution characteristics, the relationship between basins and mountains, its structural patterns and how it is associated with the surrounding structures, using the electric profile, regional seismic sections, and geological outcrops. The paper also discusses in detail the source-reservoir-caprock combination and the hydrocarbon generating condition. Finally, it describes and defines two oil and gas-bearing traps, and provides new petroleum geology proofs for the prospecting of bigger reservoirs in this depression, by the combined use of data from logging, surface outcrops, regional structure evolution, geo-chemistry and geophysics. It is this paper that first systematically studies and analyzes the surrounding structures, sedimentary, geophysical and geological characteristics, and basic geological conditions in the depression. The original ideas and comments based on this study are as follows:(1) Conducted the unification of seismic layers for the southeastern depression and the southern uplifts, set up a basic framework of strata appropriate to this area of study, obtained a brand-new understanding of the formations in the depression, and made sure that there exist such periods as Cambrian, Ordovician, Jurassic and Cretaceous in the Depression of the Tarim Basin.(2) Delineated a correct fracture system in the southeastern depression. It is an alternated,...