渤海海域渤东凹陷烃源岩特征与勘探潜力

Characteristics of Source Rocks and Exploration Potential in Bodong Sag,Bohai Sea Area

近年来渤东凹陷内油气勘探因一直未取得重大突破而陷入低谷,主力烃源岩不明确是制约该区油气勘探的核心问题。结合地震、钻井、测井和分析化验等资料,对渤东地区烃源岩地球化学指标、分布特征及成因环境进行了分析,借助盆地模拟和油源对比结果,明确了渤东凹陷的主力烃源岩层系和勘探潜力。渤东凹陷发育东三段、沙一段、沙三段和沙四段4套烃源岩,其中,沙三段烃源岩有机质类型好、丰度高,为很好的烃源岩,其生烃量占凹陷总生烃量的61%,是渤东凹陷的主力烃源岩。地质分析表明,PL9-1油田的油气主要来自渤东凹陷,预示渤东凹陷具备较大的勘探潜力。油源对比结果表明,PL9-1油田75%的原油来自于沙三段烃源岩,渤东凹陷及周缘地区今后的勘探应以寻找沙三段烃源岩生成的油气为主。

The exploration of oil and gas in Bodong Sag has come to a low stage because no breakthroughs have been achived in recent years.The unclear main hydrocarbon source rocks restrain the oil exploration in Bodong Sag.Based on interpretation of seismic profiles and plotting of basic pictures,geochemical parameters,the distribution characteristics and formation environment of hydrocarbon source rocks in Bodong Sag were analyzed.The main hydrocarbon source rocks and exploration potential of Bodong Sag were illustrated by basin simulation and oil-source correlation analysis results.The study shows that there are four sets of source rocks in Bodong Sag including Ed3,Es1,Es3 and Es4.Es3 source rocks,with best organic matter type and higher organic matter abundance,are the main hydrocarbon source rocks of Bodong Sag,while the hydrocarbon generation of Es3 source rocks accounts for 61% of the total hydrocarbon amount.The oil of PL9-1Oilfield mainly migrated from Bodong Sag,indicating the large exploration potential of Bodong Sag.The result of oil-source correlation shows that 75% of the oil of PL9-1Oilfield was derived from Es3 source rocks,so the exploration in Bodong Sag should focus the oil and gas mainly produced by Es3 source rocks.