东营凹陷沙三段断裂系统分形特征及构造储集层预测

摘要

Faults played an important role in migration and accumulation for oil and gas,for fracture caused by fault activity in improving the reservoir space and the prediction of structural reservoir.The fractal geometry is applied to study the fault systems of Es3 in Dongying depression.Fracture systems have the statistical self-similar characters and fractal characteristic in the non-scale range of 0.5 -8 km.The square of coordinate coefficients (R2 )by least squares lines fitting are more than 0.98 in log-log coordinate system of box counting number and the scale.Fractal dimension,can be used to quantify the complexity of the fracture distribution and with the in-crease of the fractal dimension,the development density of faults increased.With sedimentary facies and distri-bution of oil field,the distribution of oil field and the fractal dimension have a high degree of correlation.The areas near the fault across hydrocarbon source rocks are favorable to accumulate oil and gas.With sandstone, in the oilfield the fractal dimension of fracture system is between 0.6 and 1.3.With mudstone,the fractal di-mension of fracture system is between 0.8 and 1.2.Based on this understanding,the structural reservoir is fa-vorable to accumulate oil and gas.In some upper Es3 ,middle Es3 ,lower Es3 areas the structural reservoir is favorable to accumulate oil and gas.%断裂活动对于油气的运移与聚集至关重要，然而伴随断裂活动形成大量的裂缝，其对于储集空间的改善及断裂对改善油气储层的定量研究却没有引起足够的重视。基于分形几何理论，对东营凹陷沙三段上、中、下3个亚段的断裂体系分布特征进行了系统的定量研究，并对东营凹陷沙三段内可能发育的构造储集层进行了预测。结果表明，在0.5～8 km的研究标定尺度范围内，东营凹陷沙三段断裂体系的平面分布具有良好的自相似性（相关系数0.98～1），即具有良好的分形特征；研究区已探明油气藏主要分布在油源断裂附近的砂岩和泥岩之中，其中，砂岩区断裂系统分维值介于0.6～1.3，泥岩区断裂系统分维值介于0.8～1.2。预测了沙三上、中、下3个亚段有利的构造储集层区域。