有限变形法在火山岩裂缝预测中的应用

利用有限变形法把物体在变形过程中的应变和转动分离开来 ,并建立了位移函数 ,计算了转动特征量平均整旋角 ,用平均整旋角的平面变化来表示构造裂缝的发育程度和延伸方向。应用此方法对苏北盆地内东台坳陷西部金湖凹陷东南部卞闽杨构造带东部的闵桥断背斜中闵桥油田闵 2 0块火成岩裂缝进行了研究。研究表明 ,闵 2 0块在古新统阜宁组第一段和第二段中含有多个顺层的火山岩 ,并已发现火山岩油藏 ,储层空间以裂缝为主。计算结果表明 ,闵 2 0块阜宁组火山岩裂缝发育区主要分布在断块的东部和西部。东部裂缝发育区的裂缝有东西向和南北向两组 ;西部裂缝发育区的裂缝主要分为东西向和北东向两组。构造活动、断层、火山岩岩相、成岩作用等是控制火山岩裂缝发育的主要因素。

Prediction of volcanic rock fissure with finite deformation method

The strain and rotation of moving body in the process of deformation can be separated with the finite deformation method. The displacement function of moving body was established. The mean rotation angle that is a representative value of the rotation was calculated. The change of the mean rotation angle in plane can show the growth level and the strike of the fissure. Min 20 block located in north-west Minqiao oilfield in the east Bian-Min-Yang structural belt in south-east Jinhu sag of west Dongtai depression in Subei basin was investigated with this method. The result shows that there are many bedding strata of volcanic rock. Some oil reservoirs have been found in the first and second members of Funing formation of the Palaeocene in Min 20 block. The fissures in volcanic rock were mainly distributed in the east and west of the block. In the eastern area, the fissures are mainly divided into two groups of west-east and north-south strikes. In the west area, the main fissure strikes include west-east and east-north groups. Tectonic activity, faulting, volcanic rock facies and diagenesis are the dominant elements for controlling the growth of volcanic rock fissure.