LD油田断裂特征及其对油气成藏的影响

Characteristics of Faults and Their Control on Hydrocarbon Accumulation:an example from LD Oilfield,Bohai Bay Basin,China

LD油田油气平面分布区域和垂向分布层位差异明显,平面上,油气富集程度南区大于北区;垂向上,东二下段大于馆陶组和东三段。研究区勘探实践证实断裂不仅严格控制着油气组合的空间展布和圈闭形成,而且对油气聚集活动以及油藏的形成分布有着重要影响。为此,从断裂特征入手对LD油田油气差异富集规律进行研究,主要分析了油源断裂密度、断层活动速率和边界断裂产状三个主控因素。研究结果表明:油源断裂分布特征和晚期活动断裂的分布位置控制了平面上南北区油气差异富集;陡坡带边界断裂的坡坪式形态决定了不同层位有效圈闭的大小;边界断裂的坡坪式形态和断层活动速率最终控制了垂向上不同层位油气富集程度。

Plane distribution and vertical distribution of reserves are obviously different in LD Oilfield. The southern district of reserves is greater than the north, and the E3d2L reserves are greater than the Nlg and E3d3. Ex- ploration.practice confirmed that the strike-slip faults are not only strictly controlling the combination of space distri- bution and trap formation, and have an important influence on hydrocarbon accumulation gathering activities and reservoir distribution. For this, the analysis of oil and gas differential accumulation regularity from the aspects of the characteristics of faults in LD Oilfield are carried on, Mainly considering 3 main controlling factors ： the density of oil source faults, fault activity rate and occurrence of the boundary fracture. The analysis result shows development degree of oil source faults and the plane distribution of faults matching hydrocarbon accumulation period control the plane distribution of hydrocarbon accumulation. Besides, the study shows that fault activity rate and occurrence of the boundary fracture control the vertical distribution of hydrocarbon accumulation.