Tectonic Evolution Of Hetian Paleo-uplift In Tarim Basin And Its Relation To Oil And Gas

Paleo-uplift is the centre of long-time petroleum migration and accumulation, and is the one of primary petroleum-prospecting areas in the central and west district of our country. Hetian paleo-uplift was found in Tarim Basin in the recent several years. The paper depended on the thought of the relation of geology and geophysics, and used many technical ways. On the base of fully utilizing the available data about tectonic maps and structural elements, the present paper has made synthesized research that used the ways of stratigraphic sequence edge unconformity analysis and stratigraphic thickness correlation analysis, and combined seismic-data interpretation, review of paleo-structure and ancient landform and research of tectonic evolution and petroleum system, and combined region and location, plane and profile and time and spatial. By the synthesis analysis on tectonic evolution of Hetian paleo-uplift in Tarim basin, the results indicate that:(1) Hetian paleo-uplift is a sedimental and erosional paleo-uplift. The formation and evolution of the Hetian Paleo-uplift experienced three stages, that is, the uplifting and eroding stage of the Caledonian period, the depositional stage of the Hercynian period and the destroying stage of the Himalayan period, and evolved from paleo-lift to inclining strap at last. Its formation and evolution affects the generation, migration, accumulation and preservation of petroleum pools to a large extent.(2) The Paleozoic in the area has two pairs of source rocks, or Cambrian- Ordovician and Carboniferous-Permian, which are greater affected by tectonic evolution.(3) Ancient landform in the district may be divided to three belts: karst highland (Piyaman area),karst incliningCthe centre in the area) and karst depression(three depressive sink from west to east in the north area).(4) The formation and growth of structural traps and stratigraphic-unconformity traps in the area is controlled by three compressive stages of Silurian-Devonian, late Permian-Tertiary and Oligocene-Quaternary; non-structural and compound traps mainly grew in the early Paleozoic. Structural traps mostly grew in the late Paleozoic and the Cenozoic and mostly grew on the north and south belts; non-structural traps mostly grew in the northern area of the Hetian concave. Most traps in the area formed or typed at last in the Himalayan episode, dispersed on the north and south belts. The Hercynian period mainly dispersed on the central belt or the Manan structural belt.(5) Tectonic evolution of Hetian paleo-uplift has controlled oil and gas. It preserved early forming oil and gas, and retarded the evolution time of source rocks. Hetian paleo-uplift made oil-gas forming period in bulk, modulating period, transporting period and trap-forming period get best collocation in the Himalayan episode.(6)The paper founded the Cambrian+Ordovician+Carboniferous-Ordovician+ Carboniferous (1) petroleum system of the Hetian paleo-uplift Paleozoic.