蓬莱19-3油田地质特征

蓬莱１９－３油田是中海石油（中国）有限公司天津分公司与菲利普斯石油国际亚洲公司联合勘探，于１９９９年５月在渤海１１／０５区块发现的大型海上油田，目前，油田范围内已完钻１口探井，６口评价井，落帝构造圈闭面积６５km^2,其中含油面积在５０km^2以上，油田主力油层发育于上第三系明化镇组下段和馆陶组，储集层岩性为河流相的陆源碎屑岩，含油体单层厚度一般为１．５－８m，最厚可逾２０m，单井钻遇油层厚度为６３－１５１m,石油地质储量为数亿吨级，油藏早期评价结果证实，该油田具有浅层构造较破碎，油水系统复杂，油气充潢程度高，油层度大，储量丰度高等特点。

Geological characteristics and hydrocarbon accumulation pattern of Penglai 19-3 oil field

Penglai 19-3 oil field is located in the northeast of middle Bonan Uplift in Bohai Sea and on the east branch Of Tancheng-Lujiang deep faulted zone. The structure of the field is a faulted anticline developed on a palacohigh and complicated by the faults. The structural area is 65km~2. The main pay zone of the field exists in Guantao Formation and Lower Minghuazhen Formation of Neogene. The lithology of the reservoir is fluvial terrigenous clastic rock. According to the drilling data of 7 wells, the thickness of the pay zone in the field is 63-151m, the oil- bearing area is more than 50km~2 and the OOIP is hundreds of million tons. The shallow structure of this field is broken due to the well-developed faults, which results in the complicated hydrocarbon occurrence and pressure systems. This oil field is a structural layered reservoir that consists of many faulted blocks and has multiple oil-water systems in both vertical and lateral directions. Penglai 19-3 oil field is characterized by crude oil with high surface density, high viscosity and low pour point, high oil saturation pressure, little pressure difference between formation and saturation pressures, moderate dissolved gas-oil ratio and distinct biodegradation and water washing. According to the oil-source correlation analysis, the hydrocarbon of the field mainly comes from source rock of Lower Dongying Formation and Shahejie Formation of Palaeogene in the surrounding sags. According to the study of tectonic history, the development and formation of the structure and the reservoir of Penglai 19-3 oil field is closely relative to the long-term and strong tectonic movements of Tancheng-Lujiang deep faulted zone, especially many tectonic movements happened in Neogene period. Consequently developed many faults and numerous microcracks in Cenozoic formation that are good hydrocarbon migration pathways from sags to uplifts, and play an important role in finally forming the reservoir in Penglai 19-3 structure. The discovery of Penglai 19-3 oil field is a new breakthrough in hydrocarbon exploration history of Bobal Sea, having great significance for steady and sustainable development of off shore petroleum industry in China.