Oil And Gas Geological Conditions And Favorable Block Forecasting Of Carboniferous In East Xinjiang

The thesis is guided by synthetical research methods of petroleum geology. After reading a large number of relative bibliographies at home and abroad, the author summarizes the recent study situation and research methods and absorbs information of the research area and their research achievements. Through existing outcrops, profiles, core description, well logging data, backbone seismic profiles and gravitational, magnetic, electrical data, the thesis primarily discussed the oil and gas geological conditions of Carboniferous formation in East Xinjiang as a whole. The results show that East Xinjiang, except the north rim of Tuha basin, commonly develops two formations during early Carboniferous and two formations during late Carboniferous. The upper part of early Carboniferous, the middle and upper parts of late Carboniferous can be hydrocarbon source rocks. Early Carboniferous and the middle and upper parts of late Carboniferous are good reservoir rocks. The analysis of tectonic evolution demonstrates the developing period of hydrocarbon source rocks and reservoir rocks.The thesis preliminarily analyses the oil and gas accumulation conditions of Carboniferous formation in East Xinjiang by a series of common technologies and methods, such as source rock analysis, thin section observation and description, the combination features of source, reservoir and cap rocks and so on. The research figures out that Carboniferous source rocks in East Xinjiang generally match with seven advantageous subsidence zone, and are mainly developed during late period of early Carboniferous and middle and late periods of late Carboniferous, which matches with the research result of oil and gas geological conditions. The results of synthetical evaluation reveal that the upper part of early Carboniferous source rocks is moderate-good, the middle and upper parts of late Carboniferous are good, and the bottom part is moderate-good. Carboniferous reservoirs in East Xinjiang are mainly volcanic reservoirs, including weathering crust(C2k) and insider type(C₂h). Generally, physical property of the former is better than the latter. Effective reservoirs are mainly existed in the uplift areas in Tuha basin, while in Santanghu effective reservoirs are existed in both uplift areas and depression areas. At least four regional cap formations are developed during Carboniferous in East Xinjiang, the upper part of early Carboniferous, the middle and upper parts of late Carboniferous and the bottom of Permain period are included. The combination types of source, reservoir and cap rock are mostly bottom-source-upper-reservoir-top-cap type and the formation generates, reserves and seals oil and gas by itself. In the view of time, the formation generates oil and gas first and reserves them afterwards, or generates and reserves simultaneously.On the basis of the research of oil and gas geological conditions and their reservoir conditions, combing with the distribution features of structural trap, taking tectonic evolution into consideration, the thesis summaries up the distribution features of possibly favorable blocks. After verifying though exploration and practice, the thesis concludes that the favorable blocks in Tuha basin are as follows (except for the present key exploration blocks and those are in the exploration deployment range): during early Carboniferous, the south of Takequan bulge in the middle of Tuha and the east of Huoshizhen depression in northeast of Tuha; during late Carboniferous, Huoshizhen depression and the middle of Tuokexun depression which is less favorable. In Santanghu basin the favorable blocks are as follows:during Haerjiawu formation, Naomaohu depression in the west and the less favorable blocks including Wutong depression in the northwest and Weibei bulge in the south; Kalagang formation, Wutong depression in the northwest of Santanghu basin.