Special Oil & Gas Reservoirs ›› 2023, Vol. 30 ›› Issue (2): 78-85.DOI: 10.3969/j.issn.1006-6535.2023.02.011

• Geologic Exploration • Previous Articles     Next Articles

Enrichment Characteristics and Potential Area Prediction of Chang9 Reservoir in Huaqing Area of Ordos Basin

Yang Hao1,2, Yang Bo3, Shi Wei3, Lin Li3, Fang Yan3, Zhu Yushuang1,2   

  1. 1. State Key Laboratory of Continental Dynamics, Xi'an, Shaanxi 710069, China;
    2. Northwestern University, Xi'an, Shaanxi 710069, China;
    3. PetroChina Changqing Oilfield Company, Qingcheng, Gansu 745100, China
  • Received:2022-04-21 Revised:2023-01-04 Online:2023-04-25 Published:2023-05-29

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Abstract: In response to unclear understanding of distribution pattern and enrichment characteristics of Chang9 Reservoir in Huaqing Area, Ordos Basin, which restricts the exploration and development of the study area, after a comprehensive comparison and analysis of the tectonic characteristics, petrological characteristics, reservoir pore space and sand body development characteristics of Chang9 Reservoir, the enrichment rule and potential area of Chang9 Reservoir in the study area were discussed according to the characteristics of excess pressure distribution and hydrocarbon accumulation configuration of Chang7 Reservoir. The results show that the local low-amplitude structure and fracture development in Chang9 Reservoir are favorable for hydrocarbon migration and accumulation. Feldspathic lithic sandstone and lithic sandstone are developed in Chang9 Reservoir. The interstitial materials are chlorite, turbidite and ferrocalcite, followed by hydromica and silicalite. The reservoir pores of Chang9 Reservoir are mainly intergranular pores and feldspar dissolved pores, leading to extremely low porosity and permeability, so Chang9 Reservoir is of low porosity and permeability. The connectivity of sand bodies in Chang9 Reservoir is controlled by the environment of shallow water delta front. The differences of rhythm, interbed development and heterogeneity of other reservoirs result in the differences in hydrocarbon enrichment in the study area. The oil source of Chang9 Reservoir originates from the source rock of Chang7 Member. The source rocks are selectively filled into the reservoir under the action of the internal excess pressure of Chang7 Member, resulting in the uneven distribution of hydrocarbons in the area. According to the reservoir geological study and the characteristics of excess pressure distribution and recovery, Block Yuan521 is considered as a favorable area for the next exploration. There is much guiding significance of the study results for the deep exploration of the Chang9 Reservoir in Huaqing Area.

Key words: low-permeability sandstone, enrichment law, sedimentary sand body, Huaqing Area, Chang9 Reservoir, Ordos Basin

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