China Petroleum Exploration ›› 2022, Vol. 27 ›› Issue (1): 50-59.DOI: 10.3969/j.issn.1672-7703.2022.01.005

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Exploration discovery and implications of the Jurassic tight sandstone oil and gas reservoir in Well Ji7H in Taibei Sag, Turpan-Hami Basin

Liang Shijun1,Qian Feng1,Xiao Dongsheng2   

  1. 1 PetroChina Tuha Oilfield Company; 2 Research Institute of Exploration & Development, PetroChina Tuha Oilfield Company
  • Online:2022-01-14 Published:2022-01-14

Abstract: Turpan-Hami Basin has abundant tight sandstone gas resources. In the early exploration, only small-scale oil and gas reservoirs such as Baka, Wenjisang and Mideng were discovered in positive structural belts in the peripheral Taibei Sag. Based on the comprehensive analysis of source rocks, sedimentary systems, reservoir conditions and source rock–reservoir–cap rock assemblages, the accumulation pattern of tight sandstone oil and gas reservoir is established interior of source rocks in Taibei Sag. The study result shows that two types of high-quality source rocks are developed in Shuixigou Group in Taibei Sag, namely the coal measure source rock of Badaowan Formation, mudstone of Sangonghe Formation and coal measure source rock of the second member of Xishanyao Formation, with high TOC, good organic matter type, mature stage of thermal evolution, and widely developed in the sag; Multiple reservoir–cap rock assemblages are formed in the second and first members of Xishanyao Formation, as well as Sangonghe and Badaowan Formations. The sandstone deposits are widespread in the sag supplied by sufficient sediment sources from five braided river deltas in the west, north and south directions. The source rocks generate large-volume hydrocarbon and serve as the regional cap rocks to form multi-layer “sandwiched” type source rock–reservoir– cap rock assemblage; The sag has the favorable geological conditions for forming large-area tight sandstone gas reservoirs interior of source rocks, such as stable negative structures, good preservation conditions, high formation pressure and high maturity of source rocks. A horizontal well Ji7H was drilled based on the idea of “interior of source rock, marching towards deep sag and drilling horizontal well”, and high yield oil and gas flows of 40.37 m3/d and 51283 m3/d were obtained after fracturing by open flow with 7 mm choke. The tight sandstone condensate gas reservoir interior of source rocks supports to discover a new field of exploration and open up the prelude to the second exploration in Turpan-Hami Basin.

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