准噶尔盆地东北缘平地泉组岩体结构特征与三维模型构建

ROCK MASS STRUCTURE CHARACTERISTICS AND 3D MODELING OF THE PINGDIQUAN FORMATION,NORTHEAST MARGIN OF THE JUNGGAR BASIN

纹层和天然裂缝制约着页岩储层的压裂改造效果,精细刻画储层岩体结构是实现储层压裂改造体积最大化的首要前提。本文对准噶尔盆地东北缘平地泉组烃源岩中的纹层和天然裂缝进行了详细研究,并构建了三维岩体结构模型。首先,通过无人机近景航摄和数码照相,获取了平地泉组烃源岩直立剖面的高分辨率影像数据,然后基于影像数据构建了剖面的高精度三维数字模型并对天然裂缝和纹层结构进行了识别和解译。在此基础上,联合人工现场测量的天然裂缝及纹层参数,通过聚类分析确定了剖面主要发育3组高陡倾角裂缝,裂缝迹长均服从对数正态分布;纹层平均厚度为0.57 m,整体纹层厚度服从负指数概率分布。最后,基于天然裂缝和纹层的统计特征,利用蒙特卡罗模拟技术,分别构建了天然裂缝模型和层面模型,通过将二者叠加生成了融合天然裂缝和层面的三维岩体结构模型并得到了实测剖面的验证。该研究通过引入无人机技术获取烃源岩高陡剖面的影像数据,同步解译天然裂缝和纹层结构信息,有效提高了岩体结构表征的精细化水平,可为该盆地平地泉组烃源岩的数值模拟或物理模拟提供更加可靠的三维模型。

The laminas and natural fractures play a crucial role in controlling the hydraulic fracturing of shale reservoirs.Accurate characterization of the reservoir rock mass structure is essential for optimizing the stimulated reservoir volume.This study focuses on the laminas and natural fractures of the Pingdiquan Formation hydrocarbon source rocks in the northeastern margin of the Junggar Basin,constructing a detailed three-dimensional geological structure model.Initially,we obtained high-resolution image data of the vertical profile of the Pingdiquan Formation hydrocarbon source rocks through close aerial photography by an unmanned aerial vehicle(UAV)and digital imaging.Subsequently,we constructed a high-precision three-dimensional digital model of the profile based on the image data to identify and interpret the natural fractures and laminar structures.Combining the parameters of natural fractures and laminas measured manually on-site,we determined three main sets of high-angle fractures through cluster analysis,with fracture length following a lognormal distribution.The average thickness of the laminas was about 0.57 m,with the overall lamina thickness following a negative exponential probability distribution.Based on the statistical characteristics of natural fractures and laminas,by utilizing Monte-Carlo simulation techniques,we constructed models for natural fractures and laminas,respectively.Finally,we overlaid these models to generate a three-dimensional rock mass structure model incorporating both natural fractures and laminas and verified by the measured profile.This study introduces UAV technology to acquire high-resolution image data of steep-profiled hydrocarbon source rocks and interprets structural information on natural fractures and laminas,enhancing the refinement of rock mass structure characterization.The findings provide a more reliable three-dimensional model for numerical or physical simulations of the Pingdiquan Formation hydrocarbon source rocks in the Junggar Basin.