压裂液对页岩吸附与膨胀性能评价方法研究  

Study on Methods of Evaluating Performance of Shale to Adsorb Fracturing Fluid and Swell

作　　者：王海燕[1] 郭丽梅 刘萍[1] 胥云[1] 管保山[1] 吴家全 薛延萍 WANG Haiyan;GUO Limei;LIU Ping;XU Yun;GUAN Baoshan;WU Jiaquan;XUE Yanping(PetroChina Research Institute of Petroleum Exploration ＆ Development,CNPC, Beijing 065007;College of Chemical Engineering and Material Science, Tianjin University of Science and Technology, Tianjin 300457)

机构地区：[1]中国石油勘探开发研究院,北京065007 [2]天津科技大学化工与材料学院,天津300457

出　　处：《钻井液与完井液》2018年第2期110-115,共6页Drilling Fluid & Completion Fluid

基　　金：中国石油天然气集团公司项目"井筒工作液新材料新体系基础研究"(2016A-3903);国家重大专项"储层改造关键流体研发"(2017ZX05023003)

摘　　要：在页岩气开发的大规模体积压裂作业中,压裂液返排率一般在10%~60%,导致大量水滞留在储层内。以昭通、长宁和威远区块岩心为研究对象,采用X射线衍射分析及红外光谱法研究页岩膨胀性,重量法表征吸水机理、溶出致孔作用等,揭示不同工作液在页岩中赋存状态。结果表明,取样岩心黏土矿物含量为18%~20%,主要为绿泥石、伊利石和少量伊/蒙混层,采用蒸馏水、滑溜水、助排剂及防膨剂水溶液浸泡岩心1、3、5、7 d,XRD的1 nm处无明显变化,对比红外光谱未发现层间水吸收峰,吸液量及吸液速度与粒径及孔径成正比;超声浸泡页岩矿物溶出率为0.6%左右,主要为氯化钾和氯化钠,少量氯化钙,(BET)比表面积测试结果显示致孔作用不显著;清水浸泡粒径为0.154 mm的岩心,孔径随浸泡时间延长而减小,饱和时达到2.37%~2.85%,与孔容相当,完全占据孔容。XRD中1 nm处峰宽及峰高的变化为指导,用IR中层间水峰与硅氧峰比值进行验证,建立了评价黏土膨胀性能的方法 ;对川南岩心的评价结果显示,工作液浸泡页岩不会引起黏土膨胀;川南页岩中可溶性盐含量较低,工作液溶出致孔作用不显著;工作液中的水在足够长时间内可以进入纳米微孔道,占据微孔,但不会进入黏土矿物质晶格层间,不会因膨胀对地层造成渗透率伤害。In large-scale SRV fracturing in shale gas development, flowback rate is generally 10% to 60%, resulting in a mass of water that is trapped in the reservoir. Using XRD analysis and IR spectrometry to study the swelling property of shales taken from Zhaotong, Changning and Weiyuan. Gravimetric analysis was used to characterize the water absorption mechanisms and pore generation by dissolution. These methods reveal the state of existence of different working fluids in shales. The experimental results show that the clay contents of the shale samples are 18%-20%, mainly chlorite, illite and some illite/smectite mixed layer. The shale samples were soaked with distilled water, slick water, water solution of cleanup additive and water solution of swelling inhibitor for 1 d, 3 d, 5 d and 7 d. There is no obvious change at 1 nm on the XRD graph. IR spectrometry shows that there is no absorption peak for interlayer water. The volume of absorbed water and rate of absorption are proportional to particle size and size of pore throat. Percent of matters dissolved out of shale samples through ultrasonic soaking is about 0.6%, mainly KCl and NaCl, with minor amount of Ca Cl2. Specific surface area measured with BET method shows that pore generation is not obvious. A core with particle size of 0.154 mm was soaked in fresh water, and the sizes of pore throat were decreasing with time. The amount of water absorbed by the core was 2.37%-2.85% at saturation, equivalent to the volume of pores of the core. Using the width and height of the peak at 1 nm on the XRD graph as indicators, and ratio of interlayer water peak value over Si-O peak value on IR spectrometry graph as verification, a method for the evaluation of clay swelling property is established. Evaluation of cores taken from south Sichuan shows that the soaking of shale in working fluid does not cause clays to swell. Shales taken from south Sichuan have lower contents of soluble salts, hence the pore generation by the working fluids is not obvious. The working fluids can ente

关 键 词：压裂液 吸水机理 页岩膨胀性 返排率 吸液速度 

分 类 号：TE357.12[石油与天然气工程—油气田开发工程]