基于过程分析法的页岩原位含气性评价

Evaluation on In-situ Gas-bearing Characteristic of Shale Based on Process Analysis Method

李俊乾 卢双舫 李文镖 蔡建超

LIJunqian LUShuangfang LIWenbiao CAIJianchao

中国石油大学(华东)地球科学与技术学院, 山东 青岛 266580 中国石油大学(北京)油气资源与探测国家重点实验室, 北京 昌平 102249

School of Geosciences, China University of Petroleum(East China), Qingdao, Shandong 266580, China State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Changping, Beijing 102249, China

为了确定页岩中总含气量、吸附气/游离气含量及其比例，建立了一种新的页岩原位含气性定量评价方法，即过程分析法。该方法将钻井取芯及现场解析全过程拆分为5个阶段，依次评价不同阶段气体（吸附气、游离气）逸散量。在获取钻井取芯、储层物性、吸附/扩散、气体特性及岩芯现场解析等数据之后，使用该方法可正演计算获得全过程的气体解析量，同时获得原位总含气量、吸附气/游离气含量及其比例等数据。应用该方法对焦石坝区块JY182-6井五峰组-龙马溪组海相页岩原位含气性进行了评价。过程分析法所得总含气量是USBM直接法结果的0.8~5.4倍（平均2.0倍）；两者之间的差值为-1.27~1.58 m/t（平均0.39 m/t），且随吸附气比例的增加而逐渐减小。吸附气含量及其比例主要受控于总有机碳含量（正相关），游离气含量受控于孔隙度（正相关）和含水饱和度（负相关），同时受黏土矿物含量的影响（弱正相关）。

In order to determine the total gas content, adsorbed/free gas contents and their ratios in shale, the process analysis method, a new quantitative method of evaluating the in-situ gas-bearing characteristic of shale was established. This method divides the whole process of drilling coring and field desorption into five stages, and evaluates the amount of gas (adsorbed and free gas) released in different stages in turn. After obtaining a series of data including drilling coring, reservoir physical property, adsorption/diffusion, gas characteristic and field analysis etc., this method can be used to obtain the gas-desorbed amount during the whole process, and obtain the in-situ total gas content, adsorbed/free gas contents and their ratios. This method is used to evaluate the gas-bearing characteristic of marine shale in the Wufeng Formation-Longmaxi Formation of Well JY182-6 in Jiaoshiba Block. Total gas content obtained with the process analysis method is 0.8~5.4 times (average 2.0 times) of the results of USBM direct method; the difference between the two methods is -1.27~1.58 m/t (average 0.39 m/t), and it decreases with the increasing gas-adsorbed ratio. Adsorbed gas content and its ratio are primarily controlled by total organic carbon content (positive correlation). Free gas content is controlled by porosity (positive correlation) and water saturation (negative correlation), and is affected by clay mineral content (weak positive correlation).

10.11885/j.issn.1674-5086.2021.02.01.03