西南石油大学学报(自然科学版) ›› 2019, Vol. 41 ›› Issue (4): 23-32.DOI: 10.11885/j.issn.1674-5086.2018.04.26.05

• GEOLOGY EXPLORATION • Previous Articles     Next Articles

Fracture Characteristics of Ordovician Concealed Hills in the Anci Area and Their Significance in Petroleum Geology

XUE Hui, HAN Chunyuan, XIAO Boya, ZHAO Wenlong, LI Wenzhan   

  1. Research Institute of Petroleum Exploration and Development of Huabei Oilfield Company, PetroChina, Renqiu, Hebei 062552, China
  • Received:2018-04-26 Online:2019-08-10 Published:2019-08-10

Abstract: To resolve issues such as high heterogeneity of reservoirs and significant yield discrepancies between wells of the Ordovician concealed hills in the Anci Area, information such as core, thin section, and logging data are used to analyze the types, development, and the effectiveness of fractures in the study area. It is concluded that there are three types of fractures in the site:structural fractures, corrosion fractures, and diagenetic fractures. Structural fractures are the most developed among the three and are mostly northeast-striking high-angle fractures. Lithology and faults control the degree of development of fractures. Thin and lithologically pure dolomite reservoirs adjacent to faults contain the most developed fractures. Aperture and degree of filling reflect the effectiveness of fractures. In the study area, the developed fractures are mostly partially filled or are unfilled, thus they are relatively effective. Drilling of multiple wells confirms that these fractures are significant in petroleum geology. They can improve the physical conditions of reservoirs and provide advantageous channels for oil and gas transfer, thus increasing yields from single-wells. Meanwhile, the formation periods and development positions of fractures control the transport and accumulation of oil and gas to form reservoirs. Fractures formed after the Neogene period are highly developed and effective. Fractures inside oil-gas reservoirs are in favour of oil and gas enrichment.

Key words: fracture characteristics, degree of development, fracture effectiveness, enrichment and accumulation, Ordovician concealed hill

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