鄂尔多斯盆地姬塬油田长7段页岩油藏地质工程一体化油藏开发对策——以安83井区为例

Geology and engineering integrated development countermeasures of Chang 7 member shale oil reservoir in Jiyuan Oilfield, Ordos Basin: a case study of An 83 well block

长7段油藏作为鄂尔多斯盆地姬塬油田重要生产层段,具有埋藏深、油水关系复杂、储层非均质性强等特点,地质工程一体化技术是提高其注水开发效果的必然手段。以地质工程一体化为指导,采用室内实验建立的修正岩石力学参数计算模型进行参数修正,利用岩心、测井等计算得到单井岩石力学参数和地应力参数,采用随机建模方法建立区块三维力学模型和三维地应力场模型,根据地应力分布刻画压裂裂缝展布方向。根据渗透率和地应力展布等优化设计开发井网,利用数值模拟技术优化井网及开发技术政策,以提高采收率为目标,建立并持续更新模型,形成了地应力分析—地质建模—油藏工程设计—数值模拟一体化技术方法。研究表明:采用扁平化管理结构,多学科协同能更高效开发油藏。精细地质描述与动态分析相结合可以持续更新地质模型,建立更加逼近真实的地质模型。岩心力学实验、测井曲线计算与压裂施工等相结合,采用随机建模方法构建的地应力场模型与动态具有很好的吻合性,为动态分析、井网完善与部署提供了基础。动态井网优化与开发技术政策有效地指导了安83井区长7段储层开发,该区重复改造时建议裂缝半长为120m、缝宽为30m、主裂缝导流能力为15D·cm、次裂缝导流能力为1D·cm,优化后的5口井施工后均取得较好效果,增油倍数明显高于邻井,优化设计井较邻井能增产30.46%。

Chang 7 member oil reservoir is a major production layer in Jiyuan Oilfield in Ordos Basin, which is characterized by deep burial depth, complex oil-water contact and strong reservoir heterogeneity, so the technology of geology and engineering integration is a necessary method to improve the result of water injection development. Guided by the integration of geology and engineering, rock mechanic parameters are corrected in calculation model established by lab test results, and rock mechanic parameters and in-situ stress of single well are calculated by core and logging data, mechanic parameter and in-situ stress field models of the block are built by random modeling method,and the distribution direction of hydraulic fractures is characterized according to the in-situ stress distribution. The development well pattern is optimally designed based on permeability and in-situ stress distribution. The numerical simulation technology is used to optimize well pattern and development countermeasures, and the model is established and continuously updated with the goal of EOR, forming an integrated technology of in-situ stress analysis, geological modeling, oil reservoir engineering design, and numerical simulation. The research shows that the flat management structure and multidisciplinary cooperation enable to efficiently develop oil reservoir. The integration of fine geological description and dynamic analysis supports to continuously update the geological model and establish a model closer to the real geological condition. The random modeling method constructed in-situ stress field model by using rock mechanic data of core samples, logging data and fracturing engineering data shows good agreement with dynamic performance, which provides a basis for dynamic analysis, well pattern optimization and deployment. The dynamic well pattern optimization and development technology countermeasures effectively guided the development of Chang 7 member oil reservoir in An 83 well block. During the refracturing process, the engineering parameters were optimally designed, with the half length of fracture of 120 m, the width of fracture of 30 m, conductivity of the main fracture of 15 D·cm, and that of the secondary fracture of 1 D·cm. Good results were achieved from the five optimized wells after construction, with oil production increase multiple significantly higher than that of the adjacent well, and production capacity increase by 30.46% of the adjacent well.