China Petroleum Exploration ›› 2023, Vol. 28 ›› Issue (2): 57-69.DOI: 10.3969/j.issn.1672-7703.2023.02.006

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Exploration and development enlightenments from the discovery of Bozhong 34-9 Oilfield in southern Bohai Sea

Cui Mingzhe, Li Chao, Yuan Xun, Wu Qiongyuan, Cao Long   

  1. Tianjin Branch of CNOOC (China) Co., Ltd.
  • Online:2023-03-15 Published:2023-03-15

Abstract: Bozhong 34-9 Oilfield is characterized by the first Cenozoic sandstone oil reservoir discovered in Bohai Sea by 2022 that affected by igneous rocks the most, as well as the first in offshore oilfield development in China. Therefore, the fine identification of igneous rocks and its lateral sealing capacity for sandstone reservoir are very crucial to the high-efficiency oilfield development.By fully using core, thin section, well drilling, logging, and forward modeling data, igneous rock facies are finely characterized and identification chart is established in Bohai Sea area. The sealing capacity of igneous rocks is evaluated from aspects of petrology and logging physical property characterization, which indicates that the lithologic-structural oil reservoir is dominated in the study area,and igneous rocks mainly segment and seal oil traps. Specially, the lateral sealing capacity of igneous rocks is evaluated, the pattern of igneous rocks laterally sealing sandstone trap is summarized, and potential area is proposed. The study results show that volcanic conduit facies, intrusive facies and overflow facies igneous rocks were mainly developed in the study area, and three patterns of igneous rocks laterally sealing sandstone trap are identified, i.e., lateral sealing by dike, lateral sealing by stratified igneous rock mass or lateral non-sealing by stratified igneous rock mass. The first two types of igneous rocks lateral sealing patterns have favorable conditions for further evaluation. A total of 78 development wells have successfully been implemented in the oilfield, which enriches the exploration and development technical means of sandstone oil reservoirs in the igneous area in Bohai Sea area, and has important guiding significance for the exploration and development of similar oilfields at home and abroad.

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