水平井体积改造井距和簇间距优化研究

Well Spacing and Cluster Spacing Optimization for Horizontal Well Volume Stimulation

为研究页岩油水平井最优井距和簇间距的工程问题,针对鄂尔多斯盆地长7储层地质特征,采用地质工程一体化工作流程,建立三维地质模型和地质力学模型,模拟不同簇间距条件下的复杂缝网扩展,依据全缝长频率分布优化井距。采用非结构化数值模型预测水平井的生产动态,确定产量最高的分段分簇方案。数值模拟分析表明,采用缝长累积频率分布中P90值对应的缝长作为水平井井距,有助于提高复杂缝网对储量的控制程度,簇间距缩小到3∼5 m时建议水平井井距为200 m左右;簇间距从15 m缩小到3 m,支撑裂缝总表面积提高108%,同时体积改造程度提高142%;对于目标储层,簇间距从15 m缩小到3 m,投产3 a累产油量增加75.91%;采用3 m簇间距方案无法满足经济效益的需求,建议以5 m作为簇间距。

Aiming at well spacing and cluster spacing optimization for horizontal wells,Chang 7 Formation in Ordos Basin is studied.Based on the integrated workflow through geology to engineering,3D geological model and geomechanical model are built firstly with its geologic characteristics.Multi-stage fracturing design is simulated with various cluster spacing,and well spacing could be optimized by frequency distribution of full fracture length.Unstructured grid is used to predict the performance of a horizontal well and the best cluster spacing case is confirmed.Results from analysis of numerical simulation show that:it is recommended to optimize well spacing according to the cumulative frequency distribution of fracture length,like P90.It would be helpful to improve the controlling degree of complex fracture network on reserves.With cluster spacing ranging from 3 m to 5 m,it′s recommended to decrease lateral spacing to about 200 m;with tighter cluster spacing of 3 m instead of 15 m,the surface area of propped fractures could increase by 108%,and volume stimulation degree increase by 142%for the target formation;with tighter cluster spacing of 3 m instead of 15 m,cumulative oil production increase by 75.91%in 3 years;rate of return on investment can′t be realized by cluster spacing of 3 m,and the recommended plan would be 5 m.