柴达木盆地东坪气田基岩储层裂缝建模方法研究

东坪气田基岩气藏是罕见的非常规裂缝性气藏，有效模拟天然裂缝的发育状况及展布特征十分困难。针对这一问题，在分析东坪气田基岩气藏储集空间特征的基础上，确立了基岩储层DFN离散裂缝模型的建立思路。先基于成像测井解释的裂缝倾角、裂缝方位角等裂缝特性参数，将东坪基岩储层裂缝分为两组走向近似垂直的天然裂缝，分别模拟了两组天然裂缝的密度分布。再以裂缝密度曲线作为目标曲线、地震综合属性体作为趋势约束体，建立了DFN离散裂缝分布模型。通过提取裂缝密度、孔隙度及渗透率等属性参数，研究了东坪基岩储层裂缝的分布特征，发现裂缝主要受断层控制，平面上和纵向上均存在强的非均匀发育特性。最后，运用东坪基岩储层生产动态特征和气藏数值模拟的产量历史拟合效果检验了DFN离散裂缝模型对基岩储层的适用性。研究成果可为非常规基岩储层的裂缝模拟提供强有力的技术手段。

A Study on Fracture Modelling of the Bedrock Reservoir in Dongping Gas Field,Qaidam Basin

The bedrock gas reservoir in the Dongping Gas Field is a rare and unconventional fractured gas reservoir, and it is challenging to model the development and distribution of the naturally occurring fractures in the area. We aimed to solve this problem by establishing a Discrete Fracture Network (DFN) model of the bedrock reservoir based on the spatial characteristics of the reservoir in the Dongping gas field. We first divided these natural fractures in the Dongping Gas Field into two roughly perpendicular groups based on fracture characteristics measured in image logs, such as the inclination angle and azimuth, and we modelled the density distribution of each group. A DFN model was then built using a fracture density curve as the target curve and seismic attributes as constraints. By extracting attribute parameters such as fracture density, porosity, and permeability, we studied the distribution characteristics of the fractures in the Dongping bedrock reservoir. The results showed that these fractures are generally controlled by faults, and there is strong non-uniform development along both horizontal and vertical axes. Finally, this paper validates that the DFN model is suitable for bedrock reservoirs by demonstrating fitting between the dynamic characteristics of production in the Dongping bedrock reservoir and the modelled production of the gas reservoir.