基于随机扩展方法的致密油储层裂缝建模研究

Facture Modeling Research of Tight Oil Reservoir Based on Fracture Propagation Inversion Model

现有的储层裂缝建模方法大多忽略了储层裂缝扩展历史与裂缝属性随机分布特征之间的本质关系,所建裂缝模型多为不考虑断裂尖端扩展历史的静态模型,因而不可能给出有效的区域裂缝信息。针对裂缝建模难题,提出了基于裂缝扩展反演模型的裂缝建模方法。首先,基于裂缝扩展规律,采用扩展有限元方法,利用模拟退火技术,建立裂缝扩展反演模拟模型;然后,采用克里金模型和断裂力学模拟系统,综合构造和成像测井裂缝解释资料,构建多场趋势克里金估计模拟模型。选取大情字井地区青山口组扶余致密油层作为实验区,建立了该区块的裂缝扩展模型和裂缝分布模型。实验表明,构建的基于随机扩展有限元模拟的裂缝建模方法可以克服现有裂缝建模方法的不足,可提高裂缝性油藏的表征精度。

Fracture modeling of tight oil reservoir has become the focus of reservoir modeling technology. Because existing fracture modeling methods are mostly ignored the essential relationship between the law of fracture propagation and the distribution of fracture characteristics, and therefore impossible to give an effective information of fracture distribution. In this paper, we proposed one new fracture modeling method called stochastic extended finite element method, which is build based on fracture mechanics and multi-field Kriging method. This method established the fracture propagation inversion model firstly,based on law of fracture propagation and extended finite element method, by using annealing simulation method. Then, by integrating the Kriging system and fracture simulation system and using structure and imaging logging data, we constructed anmulti-field Kriging estimation model. Finally, based on the stochastic extended finite element simulation method, we wrote a fracture modeling system software, and build the fracture propagation model and fracture distribution model of Upper Cretaceous Qingshankou Formation in Daqingzijing area. Simulation results have shown that the fracture modeling method based on stochastic extended finite element simulation could overcome the difficult of existing fracture modeling method, and improve the characterization precision of fractured reservoir.