Characteristics Of Lower Paleozoic Fractured-Vuggy Reservoirs In The BZ28-1Area,Bonan Low Uplift,Bohai Bay Basin

With the deepening of oil and gas exploration in the Bohai Bay Basin,exploration and development of buried hill carbonate reservoirs have become an important field in China.There are various types of lithology,diagenesis and tectonic movement in the lower Paleozoic carbonate rocks of Bohai Bay Basin,which led to the superposition of fractures and vug of different stages and scales,and formed the development of the fractured-vuggy reservoirs.Therefore,microscopic observation,fluorescence,scanning electron microscopy,cathodoluminescence,electron probe microposition,petrophysical test data,logging interpretation and other test analysis methods were used to systematically study the Lower Paleozoic fractured-vuggy reservoirs in the BZ28-1 area of Bohai Bay Basin.By analyzing the characteristics of sedimentary facies,petrology,diagenesis,reservoir quality and fractured reservoirs of the Lower Paleozoic carbonate,the longitudinal distribution of the fractured-vuggy reservoir is summarized,the main controlling factors of the fractured-vuggy reservoir are analyzed,and the developmental model is established.Based on the analysis of tectonic evolution,the formation and filling period of fracture-vug are determined by the analysis of inclusions homogenization temperature and oxygen isotopes,and the reservoir evolution were summarized.The development of Lower Paleozoic fractured-vuggy reservoirs in BZ28-1 area of Bohai Bay Basin is controlled by various factors: tectonic movement and epistatic karst are main factors controlling the formation of fractured reservoirs;Dolomite,dolomitic flat,karst slopes and highlands,multiphase structural cracks are favorable factors influencing the formation of fractured-vuggy reservoirs.The crosscutting relationships of fracture-vug,the inclusions homogenization temperature and oxygen isotopes temperature of filling,the characteristic of geochemistry and geohistory were used to study fractured-vuggy reservoirs.The cave is mainly occurred at the Caledonian period,the Indosinian period and the late Yanshan period;Before hydrocarbon charging,the are four stage fracture,they are mainly occurred at the Hercynian or early Indosinian period,the middle Yanshan period,the Himalayan rift I screen period,the Himalayan rift II screen period;fracture-vug filling occurred at the Hercynian period or early Indosinian period,the middle Yanshan or Himalayan period.The Himalayan period was the peak period of filling that mainly formed in the deposition period of Minghua town formation.