Hydrocarbon preservation and exploration in Bachu Uplift of Tarim Basin

The Bachu Uplift of the Tarim Basin had experienced several tectonic movements during the middle Caledonian(the end of the Late Ordovician),the early Hercynian(the end of the Middle Devonian),the late Hercynian(the Late Permian),the Indosinian-Yanshanian and the Himalayan,among which the middle Himalayan was the most important stage for uplift formation.Different stages of tectonic movements had great effects on hydrocarbon preservation conditions.The Middle Cambrian gypsum-salt rocks,the Middle-Lower Carboniferous mudstones and the Lower Permian Kupukuziman Formation mudstones were good regional cap rocks in the region.Based on integrated analyses of seal properties and hydrocarbon preserving conditions,it was pointed out that there were 2 locations with better conditions for hydrocarbon preservation in the uplift:the southern margin and the east part.Vertically,horizons under the Middle-Lower Cambrian salts were favorable for preservation.Therefore,the southern margin and the east part of the Bachu Uplift as well as the Middle-Lower Cambrian subsalt reservoirs are the favorable targets for future petroleum exploration.