河套盆地洼槽区河探1井风险勘探突破及意义

在中国东部断陷盆地发现规模富集油气藏的难度越来越大,通过解放思想、创新认识,在新的地质理论指导下,2018年以来,先后在河套盆地西部陡带吉兰泰构造带、中部纳林湖构造带和北部兴隆构造带取得石油勘探重大突破,相继发现了吉兰泰和巴彦两大油田,揭示了晚深埋、晚生烃、弱成岩、晚成藏的地质发育特征和油气临洼近源富集的成藏特点。2021年,基于洼槽区具有资源潜力大、勘探面积广、构造背景好的有利条件,在兴隆构造带临洼有利构造部署风险探井——河探1井,在6 112~6 120 m井段试油获302.4 m³/d高产工业油流,实现了洼槽区碎屑岩领域超深层石油勘探重大突破。分析认为,晚期构造反转叠加大型滑脱断层控圈,晚深埋、弱成岩叠加超高压控储作用以及大型鼻隆构造背景汇聚控富集的有利地质条件是形成洼槽区高产富集的关键因素。河探1井的成功钻探有力拓展了河套盆地油气勘探空间,为河套盆地建成年产200×10⁴t以上油田并保持持续稳产提供了坚实的资源保障,同时对陆相断陷湖盆(超)深层洼槽区勘探具有重要的借鉴作用。

Breakthrough and significance of risk exploration of Well Hetan 1 in the trough area of Hetao Basin

It is more and more difficult to find large-scale enriched oil-gas reservoir in rift basins in eastern China.Based on emancipation of the mind and understanding innovation,under the guidance of new geological theories,since 2018,major breakthroughs in oil exploration have been made in the Jilantai tectonic zone in the western steep zone of Hetao Basin,the Nalinhu tectonic zone in the middle and the Xinglong tectonic zone in the north.Moreover,Jilantai and Bayan oilfields have been successively discovered,revealing the geological development characteristics of late deep burial,late hydrocarbon generation,weak diagenesis and late accumulation,and the hydrocarbon accumulation characteristics such as enrichment of oil and gas near troughs and sources.In 2021,based on the favorable conditions including large resource potential,wide exploration area and good tectonic background in the trough area,the exploratory Well Hetan 1 was deployed in the favorable structure near the trough in the Xinglong tectonic zone,and a high-yield industrial oil flow of 302.4 m³/d was obtained during formation testing in the well section of 6 112 m to 6 120 m,thus achieving a major breakthrough in ultra-deep oil exploration in clastic rock field in the trough area.The analysis shows that the favorable geological conditions such as late tectonic inversion superimposed with trap controlling by large-scale detachment fault,late deep burial,weak diagenesis superimposed with ultra-high pressure reservoir control,and hydrocarbon convergence-controlling enrichment under large-scale nose tectonic background are the key factors for oil and gas accumulation and high production in the trough area.The successful drilling of Well Hetan 1 has effectively expanded the oil and gas exploration space in Hetao Basin,providing a solid resource guarantee for building an oilfield with an annual output of more than 2 million tons in Hetao Basin and maintaining sustainable and stable production,and an important reference for the exploration in (ultra) deep troughs in continental rift lake basins.