页岩油探井现场地质评价实验流程与技术进展

Experimental procedures of well-site geological evaluation for shale oil and related technological progress

页岩油勘探钻完井过程中需要及时对页岩含油性及页岩油的可动性进行快速评价,而已有的现场评价技术主要适用于常规砂岩储层,难于满足页岩非均质性描述的需求,迫切需要建立针对性的实验技术序列。根据页岩油探井现场快速地质评价客观需求,结合实验仪器的客观技术指标,提出了现场实验项目、取样保存和实验技术流程,并开展了现场技术方法实验和应用研究,研制磁流体变密度岩石总体积测试装置,解决了易松散形变页岩难于取柱塞样而无法及时获取物性参数的难题,建立了无固定形状页岩物性分析技术;采用液氮冷冻密闭粉碎制样技术避免轻烃损失,岩石热解分析数据更为真实;优化现场测试项目之间以及现场和实验室分析项目之间的衔接,实验支撑更为高效。新技术在江汉盆地潜江组、济阳坳陷沙河街组和鄂尔多斯盆地延长组七段应用效果显著,为陆相页岩油勘探快速地质评价提供了科学依据。同时也需要指出,中国目前页岩油勘探现场实验技术还不完善,还没有相应的规范标准,下一步攻关方向应该是,在完善现场实验技术和应用技术的基础上,形成规范的方法技术体系,搭建页岩油勘探快速地质评价技术平台。

In the drilling and completion process of a shale oil exploration well,it is necessary to evaluate the oil-bearing property and movability of shale oil in time.However,the existing well-site evaluation techniques are developed primarily for conventional sandstone reservoirs,thus cannot meet the requirements of shale heterogeneity description.Therefore,it is in urgent need to establish a specific experimental procedure for shale oil drilling.In accordance with the requirements of rapid well-site geological evaluation and the technical limitations of available instrumentations,we proposed item selection,sampling,sample preservation and technical workflow for on-site experiment.Furthermore,this workflow was tested and applied in several well-site operations.A magnetohydrodynamic variable density rock bulk volume testing device was developed to solve the problem that it is hard to rapidly measure physical properties due to the difficulty to sample plungers for shales prone to loose and deform.In addition,a technique was invented to analyze the physical properties of shales with no fixed geometry.In order to minimize the evaporative loss of light hydrocarbons and to make Rock-Eval pyrolysis analysis data more reliable,shale samples were ground in liquid nitrogen freezing instruments.Analytical programs for well-site and lab tests were optimized and synergized to ensure more efficient workflow.These new methods were applied successfully to the Qianjiang Formation in Jianghan Basin,Shahejie Formation in Jiyang Depression and Chang 7 in Ordos Basin,laying a sound foundation for fast geological evaluation of continental shale oil exploration.Meanwhile,what should be pointed out is that the current well-site experimental technology is still far from perfect for China's shale oil exploration,for instance,a lack of related specifications and criteria.What we should do further is to improve the existing well-site experimental and applied technologies,develop normative methodology and technology systems,and build a rapid geological evaluation platform for shale oil exploration.