China Petroleum Exploration ›› 2020, Vol. 25 ›› Issue (6): 1-12.DOI: 10.3969/j.issn.1672-7703.2020.06.001

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New understandings of petroleum geology and a major discovery in the Linhe depression, Hetao Basin

Zhang Ruifeng1,He Haiqing2,Chen Shuguang1,Li Guoxin2,Liu Xiheng1, Guo Xujie2, Wang Shaochun1,Fan Tuzhi2,Wang Huilai1,Liu Jing1, Cao Lanzhu1   

  1. 1 PetroChina Huabei Oilfi eld Company; 2 Petrochian Research Insititute of Petroleum Exploration & Development
  • Online:2020-11-12 Published:2020-11-12
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Abstract: The Hetao Basin is a Meso-Cenozoic depression-fault superimposed basin. For a long time, there were no seismic survey lines and little understanding of tectonic evolution, source rock development and hydrocarbon accumulation controlling factors, and accumulation laws. As a result, oil and gas exploration was limited and discoveries are few. In recent years, exploration ideas have changed. Fine structural interpretation from well-seismic combination and comprehensive evaluation on favorable plays based on field outcrop surveys and 2D infill seismic lines has led to new understandings of the tectonic evolution mechanisms. The Linhe depression has experienced four stages of tectonic evolution: an Early Cretaceous inversion and basin-forming stage, a Paleogene differential extension stage, a Neogene intensive extension fault stage, and a Quaternary strike-slip (or inversion) and reconstruction stage. It has also been determined that the Jilantai structural belt and the central fault belt are favorable areas for oil and gas exploration. There are three sets of source rocks in the Linhe depression: the 2nd member of the Guyang Formation (the Gu 2 member), the 1st member of the Guyang Formation (the Gu 1 member), and the Linhe Formation. Quantitative characterization of source rock distribution in different sedimentary periods has revealed the controlling laws of the three combined elements of “basin evolution - sedimentary environment - burial history”, with the central-northern area of the Linhe depression being identified as the predominant resource enrichment area. Comprehensive analysis of hydrocarbon accumulation conditions has established several new hydrocarbon accumulation models for inside and outside the source rocks. Based on this new understanding, metamorphic buried hill oil reservoirs and clastic fault-nose structural oil reservoirs have been discovered in the Jilantai structural belt in the central-southern Linhe depression, marking a major breakthrough in oil and gas exploration in the Archean buried hill and the Cretaceous system outside the source rocks. In the northern Linhe depression, a risk exploration well—Well Linhua 1X—was drilled, obtaining high flow rate of 305.76 m3/d in the Paleogene inside the source rocks. This represents another breakthrough in multi-belt and multi-layer exploration in the Linhe depression.

 

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