西南石油大学学报(自然科学版) ›› 2019, Vol. 41 ›› Issue (5): 21-32.DOI: 10.11885/j.issn.1674-5086.2018.09.02.03

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Characteristics of High-quality Reservoirs in the Braided River Delta in Kenli-A Oilfield

ZHAO Hanqing, GUO Cheng, CHEN Xiaoming, LIU Chao, ZHANG Bo   

  1. CNOOC China Limited, Tianjin Branch, Tanggu, Tianjin 300459, China
  • Received:2018-09-02 Online:2019-10-10 Published:2019-10-10

Abstract:

A clear understanding of the characteristics and genesis of high-quality reservoirs in Kenli A Oilfield in the Laizhou Bay Sag of the Bohai Bay Basin in Upper Es3 of the Paleogene Shahejie Formation can provide a foundation for oil and gas exploration in the depression. Combining data from drilling, logging, thin section casting, scanning electron microscopy, physical properties, fluid inclusions, and other analytical testing methods, the regional tectonic background, burial history, and sedimentary systems were investigated. The upper reservoir of the Shahejie Formation exhibited characteristics of "high porosity and high permeability" and the reservoir space was shown to be dominated by intergranular pores with relatively welldeveloped micro-cracks. The pore throat can be classified as large-medium or medium-small throat. The reservoir diagenetic effect is generally observed in middle diagenetic stage A, which is characterized by "medium compaction, strong dissolution, and weak cementation". The formation of high-quality reservoirs is affected by four main aspects:Tectonic setting, sedimentary environment, diagenesis, and overpressure of the formation. Reservoir development in the southern slope of the Laizhou Bay Sag is zonal, where high-quality reservoirs develop on the inner side of the gravity slip fault (F1), providing a favorable area for oil and gas accumulation.

Key words: Bohai Bay Basin, braided river delta front, reservoir quality, diagenesis, physical control factors

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