基于分形理论和三维地质力学模拟定量预测亚地震断层

项目名称： 基于分形理论和三维地质力学模拟定量预测亚地震断层

项目编号： No.41502124

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 天文学、地球科学

项目作者： 巩磊

作者单位： 东北石油大学

项目金额： 21万元

中文摘要： 在断块油气田中，发育有大量低于地震分辨率的亚地震断层。在钻井过程中，可以钻遇部分亚地震断层，然而大部分是没有被发现的。这些亚地震断层是控制有效储层形成、油气成藏和注水开发效果的关键因素。利用不同尺度下断层的自相似性（或标度不变性），可以通过外推地震尺度上测量的断层参数（长度、断距等）分布，获得亚地震断层的尺度分布。然而，亚地震断层的位置和方位是不能通过该方法确定的。为此，本项目提出了一种基于断层分形生长模式和三维地质力学模拟相结合的方法来确定亚地震断层的数量、发育位置和方位。将地震上识别的大尺度断层引入到三维数值力学模型中，模拟断层形成时期断裂带附近的应力扰动作用，然后结合破裂准则来建立最易发生破裂的方位和密度网格，最后以这两套网格和断层尺度的幂律分布确定的亚地震断层数量为约束条件来确定随机模型，对亚地震断层分布进行模拟。

中文关键词： 亚地震断层；定量预测；分形几何；三维地质力学模拟

英文摘要： Within any faulted reservoir, there are large numbers of faults that are below the resolution of seismic surveys. Some of these faults are encountered in wells, but most of them remain undetected. Such subseismic faults can significantly influence the formation of effective reservoir, hydrocarbon accumulation and water-flood development during production. The size distribution of subseismic faults can be predicted by extrapolating the size distribution measured at the seismic scale down to the subseismic scale. However, the positions and orientations of the subseismic faults are more difficult to determine. A method based on fractal geometry and 3D geomechanical modeling is described here to constrain the positions and orientations of subseismic faults. The large, seismically resolvable faults are brought into a three-dimensional (3-D) numerical mechanical model to determine the stress conditions near these faults at the time of faulting. The stress field is then combined with a Coulomb failure criterion to predict the orientations and densities of the fractures. This information is represented on a pair of grids (i.e., a density and strike grid). The grids are then used to condition stochastic models of faulting, which use a power-law distribution and/or stochastic growth processes to simulate subseismic faults.

英文关键词： Subseismic Fault;Quantitative Prediction;Fractal Geometry;3D Geochanical modeling