压裂液对页岩吸附与膨胀性能评价方法研究
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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 enter into the nanometer-sized micro pores in time is enough. The working fluid will occupy the micro pores, but will not enter into the spaces between crystal layers of clay, and will not cause the permeability of formations to be impaired by swelling.
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 enter into the nanometer-sized micro pores in time is enough. The working fluid will occupy the micro pores, but will not enter into the spaces between crystal layers of clay, and will not cause the permeability of formations to be impaired by swelling.
引文
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[14]徐克彬,任勇强,王中泽,等.一种基于阳离子稠化剂的高抗盐压裂液研究及应用[J].钻井液与完井液,2017,34(3):99-104.XU Kebin,REN Yongqiang,WANG Zhongze,et al.Study and application of a high temperature salt-resistant fracturing fluidformulated with a cationic thickening agent[J].Drilling Fluid&Completion Fluid,2017,34(3):99-104.
[15]赵军,张劲,肖丽佳,等.耐高温阴离子表面活性剂压裂液的性能评价及现场应用[J].钻采工艺,2015,38(1):86-90.ZHAO Jun,ZHANG Jin,XIAO Lijia,et al.Performance evaluation and field application of high temperatureanionic sufactant fracturing fluid[J].Drilling&Production Technology,2015,38(1):86-90.
[16]陈作,曾义金.深层页岩气分段压裂技术现状及发展建议[J].石油钻探技术,2016,44(1):6-11.CHEN Zuo,ZENG Yijin.Present situations and prospects of multi-stage fracturing technology for deep shale gas development[J].Petroleum Drilling Techniques,2016,44(1):6-11.
[17]李伟,马洪芬,郝鹏涛,等.一种低浓度瓜胶压裂液用p H值调节剂[J].钻井液与完井液,2017,34(5):117-122.LI Wei,MA Hongfen,HAO Pengtao,et al.A p H regulator used in low concentration HPGG fracturing fluids[J].Drilling Fluid&Completion Fluid,2017,34(5):117-122.
[2]李勇明,彭瑀,王中泽.页岩气压裂增产机理与施工技术分析[J].西南石油大学学报,2013,35(2):90-96.LI Yongming,PENG Yu,WANG Zhongze.Analysis of Shale fracture stimulation mechanism and operating techniques[J].Journal of Southwest Petroleum University,2013,35(2):90-96.
[3]陈鹏飞,刘友权,邓素芬,等.页岩气体积压裂滑溜水的研究及应用[J].石油与天然气化工,2013,42(3):270-273.CHEN Pengfei,LIU Youquan,DENG Sufen,et al.Research and application of slick water for shale volume fracturing[J].Chemical Engineering of Oli&Gas,2013,42(3):270-273.
[4]霍丙夏,郭丽梅,管保山,等.快速增黏滑溜水降阻剂的研制[J].现代化工,2016,36(1):78-81.HUO Bingxia,GUO Limei,GUAN Baoshan,et al.Development of resistance-reducing agent with rapid thickening property for slick-water[J].Modern Chemical Industry,2016,36(1):78-81.
[5]张磊,康钦军,姚军,等.页岩压裂中压裂液返排率低的孔隙尺度模拟与解释[J].科学通报,2014,32(59):3197-3203.ZHANG Lei,KANG Qinjun,YAO Jun,et al.The explanation of low recovery of fracturing fluid in shale fracturing by pore-scale[J].Chin Sci Bull,2014,32(59):3197-3203.
[6]HORN A D.Breakthrough mobile water treatment converts75%of fracturing flowback fluid to fresh water and lowers CO2 emissions[C]//SPE Americas E&P Environmental and Safety Conference.Society of Petroleum Engineers,2009.
[7]陈志鹏,梁兴,张介辉.昭通国家级示范区龙马溪组页岩气储层超压成因浅析[J].天然气地球科学,2016,3(27):442-448.CHEN Zhipeng,LIANG Xing,ZHANG Jiehui,et al.Genesis anlysis of shale reservoir overpressure of longmaxi formation in zhaotong demonstration area,dianqianbei depression[J].Natural Gas Geoscience,2016,3(27):442-448.
[8]尹长河,王廷栋,王顺玉,等.威远、资阳震旦系干酪根与油裂解气的鉴别[J].沉积学报,2001,19(1):156-160.YIN Changhe,WANG Tingdong,WANG Shunyu,et al.Differences between kerogen and oil cracked gases in sinian reservoirs of weiyuan and ziyang area[J].Acta Sedimentologica Sinica,2001,19(1):156-160.
[9]王晋.1M伊利石对甲烷吸附的分子模拟[D].太原理工大学,2015.WANG Jin.Methane adsorption in illite by molecular simulation[D].Taiyuan University of Technology,2015.
[10]QIAO L Y,RANJITH P G,LONG Xinping,et al.A review of shale swelling by water adsorption[J].Journal of Natural Gas Science and Engineering,2015,27:1421-1431.
[11]郭丽梅,崔岩,管宝山,等.黏土稳定剂评价方法[J].精细石油化工,2010,27(6):72-75.GUO Limei,CUI Yan,GUAN Baoshan,et al.Aanlysis of evaluating methods of clastabilzers[J].Speclaity Petrochemicals,2010,27(6):72-75.
[12]杨志刚,魏彦林,吕雷,等.页岩气压裂返排液回用处理技术研究与应用[J].天然气工业,2015,35(5):131-137.YANG Zhigang,WEI Yanlin,LYU Lei,et al.Researchand application of recycling treatment technology for shale gas fracturing flowback fluid:A case study[J].Natural Gas Industry,2015,35(5):131-137.
[13]李伟,秦胜飞,胡国艺,等.水溶气脱溶成藏[J].石油勘探与开发,2011,38(6):662-669.LI Wei,QIN Shangfei,HU Guoyi,et al.Accumulation of water-soluble gas by degasification[J].Petroleum Exploration and Development,2011,38(6):662-669.
[14]徐克彬,任勇强,王中泽,等.一种基于阳离子稠化剂的高抗盐压裂液研究及应用[J].钻井液与完井液,2017,34(3):99-104.XU Kebin,REN Yongqiang,WANG Zhongze,et al.Study and application of a high temperature salt-resistant fracturing fluidformulated with a cationic thickening agent[J].Drilling Fluid&Completion Fluid,2017,34(3):99-104.
[15]赵军,张劲,肖丽佳,等.耐高温阴离子表面活性剂压裂液的性能评价及现场应用[J].钻采工艺,2015,38(1):86-90.ZHAO Jun,ZHANG Jin,XIAO Lijia,et al.Performance evaluation and field application of high temperatureanionic sufactant fracturing fluid[J].Drilling&Production Technology,2015,38(1):86-90.
[16]陈作,曾义金.深层页岩气分段压裂技术现状及发展建议[J].石油钻探技术,2016,44(1):6-11.CHEN Zuo,ZENG Yijin.Present situations and prospects of multi-stage fracturing technology for deep shale gas development[J].Petroleum Drilling Techniques,2016,44(1):6-11.
[17]李伟,马洪芬,郝鹏涛,等.一种低浓度瓜胶压裂液用p H值调节剂[J].钻井液与完井液,2017,34(5):117-122.LI Wei,MA Hongfen,HAO Pengtao,et al.A p H regulator used in low concentration HPGG fracturing fluids[J].Drilling Fluid&Completion Fluid,2017,34(5):117-122.