Investigation into natural fractures is extremely important for the exploration and development of low-permeability reservoirs. Previous studies have proven that abundant oil resources are present in the Upper Triassic Yanchang Formation Chang 7 oil-bearing layer of the Ordos Basin, which are accumulated in typical low-permeability shale reservoirs. Natural fractures are important storage spaces and flow pathways for shale oil. In this study, characteristics of natural fractures in the Chang 7 oil-bearing layer are first analyzed. The results indicate that most fractures are shear fractures in the Heshui region, which are characterized by high-angle, unfilled, and ENE-WSW-trending strike. Subsequently, natural fracture distributions in the Yanchang Formation Chang 7 oil-bearing layer of the study area are predicted based on the R/S analysis approach. Logs of AC, CAL, ILD, LL8, and DEN are selected and used for fracture prediction in this study, and the R(n)/S(n) curves of each log are calculated. The quadratic derivatives are calculated to identify the concave points in the R(n)/S(n) curve, indicating the location where natural fracture develops. Considering the difference in sensitivity of each log to natural fracture, gray prediction analysis is used to construct a new parameter, fracture prediction indicator K, to quantitatively predict fracture development. In addition, fracture development among different wells is compared. The results show that parameter K responds well to fracture development. Some minor errors may probably be caused by the heterogeneity of the reservoir, limitation of core range and fracture size, dip angle, filling minerals, etc.

对天然裂缝的调查对于低渗透油藏的勘探和开发极为重要。先前的研究已经证明，鄂尔多斯盆地上三叠统延长组长7油层中存在丰富的石油资源，这些石油资源聚集在典型的低渗透页岩油藏中。天然裂缝是页岩油的重要储存空间和流动通道。在这项研究中，首先分析了长7油层的天然裂缝特征。结果表明，在河水地区，大多数裂缝为剪切裂缝，其特征是大角度，未充填，ENE-WSW趋势走向。随后，根据预测结果，预测了研究区延长组长7油层的天然裂缝分布。R / S分析方法。在本研究中，选择AC，CAL，ILD，LL8和DEN的测井曲线并将其用于裂缝预测，并计算每个测井曲线的R（n）/ S（n）曲线。计算二次导数以识别R（n）/ S（n）曲线中的凹点，指示自然裂缝发展的位置。考虑到每个测井曲线对天然裂缝敏感性的差异，使用灰色预测分析来构造一个新参数，即裂缝预测指标K，以定量预测骨折的发展。另外，比较了不同井之间的裂缝发展。结果表明，参数K对裂缝的发展响应良好。一些轻微的错误可能是由储层的非均质性，岩心范围和裂缝尺寸的限制，倾角，填充矿物等引起的。