生长断层封闭性分析

Sealing analysis of growth fault

生长断层成长初期具有独特的断面形态 ,断层两盘在错动过程之中会产生空隙带和闭合带两种应力状态。在空隙带 ,两盘欠压实页岩易延展流动而产生变形的剪切沉积物 ,形成的泥质剪切带是生长断层形成泥质涂抹层的原因。泥质涂抹层的形成与断距大小、剖面岩性组合特征及泥岩含量等密切相关。生长断层多为盆地内二、三级断层 ,走向延伸较长 ,在同一层位不同地段其断距大小、上下盘岩性组合及对接关系不同 ,致使封闭性在走向上具分段特征。以大港油田张东断层为例分析生长断层封闭性 ,首先要整体认识 ,在具体地段不同层位 ,分段分析断距变化规律及岩性组合特征 ,然后比较各段形成泥质涂抹层的强弱 ,最后进行相对评价。图 5参 9(刘东周摘 )

Growth faults have special fault plane form in their initial phase during which the displacement of the two blocks creates two kinds of stress states pore belt and sealing belt. It is easy to produce ductile flow in the undercompacked shale of the two blocks to create deformentation and then to form muddy sheared zone, which is the origin to form the muddy smearing belt of the growth fault. The formation of the muddy smear has close relationship with fault throw, lithologic composition feature and mudstone content. The growth faults are the second or the third order faults in the basin, which extend a long distance in their strike. They have different throw in the different segements of the same horizon, and different lithologic assemblages in the hanging and downthrown blocks of a fault, which makes the sealing having the segmented feature in the fault strike. It is necessary to analyze the sealing to growth fault relation as a whole and segmentedly and then in different horizons of a particular sector to analyze the throw variation pattern and the lithologic assemblage feature and finally, compare and evaluate the strong and weakness of the muddy smear in each section as well.