基于钻井岩屑评价水平井地层力学性质——以鄂尔多斯盆地太原组灰岩为例

Evaluation of Formation Mechanical Properties Along Horizontal Well Based onDrilling Cuttings: A Case Study of TaiyuanFormation Limestone in Ordos Basin

鄂尔多斯盆地太原组致密灰岩气藏储层开发潜力高,规模化开发建产依赖于分段体积压裂技术。水平井井段取心难度大、成本高,难以获取全井段力学性质以支撑压裂方案精细优化,但全井段钻井岩屑可轻易获取。文章创新性地提出了一种基于钻井岩屑评价水平井地层力学性质的方法。通过开展井下岩心的单轴/三轴压缩实验和纳米压痕测试,明确灰岩的微观组分模型,研究单一组分响应与宏观整体响应的关系。针对同井同深度的钻井岩屑和井下岩心开展网格化纳米压痕测试,标定钻井岩屑与井下岩心力学性质的关系,基于钻井岩屑建立水平井地层力学性质连续剖面。应用实例表明,基于钻井岩屑的纳米压痕测试,有利于精细化表征水平井地层岩性和连续反演水平井地层的静态弹性模量分布,为水平井地层压裂甜点识别、压裂段簇及射孔优化提供基础数据。研究结果证明了基于钻井岩屑表征地层岩石力学性质的可行性,为水平井全井段储层力学性质剖面的建立提供新思路,有助于水平井密切割压裂方案的精细优化。

The tight limestone gas reservoir of Taiyuan Formation in Ordos Basin has high reservoir development potential large scale development and production depend on segmented volume fracturing technology.Horizontal well coring is difficult and costly,and it is difficult to obtain the mechanical properties of the whole well section,which supports the fine optimization of horizontal well fracturing scheme.The drilling cuttings of the whole well can be easily obtained.Therefore,an innovative method for evaluating horizontal well formation mechanical properties based on drilling cuttings is proposed in this paper.Through uniaxial/triaxial compression test and nanoindentation test of underground core,the microscopic component model of limestone is defined,and the relationship between single component response and macroscopic overall response is studied.The grid nanoindentation test is carried out for drilling cuttings and downhole core at the same depth in the same well,the relationship between drilling cuttings and mechanical properties of downhole core is calibrated,and a continuous section of horizontal well formation mechanical properties is established based on drilling cuttings.The application examples show that the nano-indentation test based on drilling cuttings is conducive to the fine characterization of horizontal well formation lithology and the continuous inversion of static elastic modulus distribution of horizontal well formation,and provides basic data for the identification of fracturing sweet spots,fracturing cluster and perforation optimization of horizontal well formation.The research results prove that it is feasible to characterize rock mechanical properties based on drilling cuttings,and provide a new idea for the establishment of reservoir mechanical properties profile in the whole section of horizontal well,which is conducive to the fine optimization of hydraulic fracturing in horizontal Wells.