无伤害压裂液的研究与应用_英文_

№.5 陕西科技大学学报 Oct.2008 Vol.26 J OURNAL OF SHAANXI UN IV ERSIT Y OF SCIENCE&TECHNOLO GY ・33・3　文章编号:100025811(2008)0520033206STU DY AN D APPL ICATION OF NON2DAMAGINGFRACTURING FL UIDL I Lin2di,ZHAN G Shi2cheng,ZHAN G Jin(MO E Key Laboratory of Petroleum Engineering in China University of Petroleum,Beijing　102249,China)Abstract:As an external fluid,f ract uring fluid harms formation in various extent s.There2fore,decreasing t he damage is t he prerequisite to imp roving f ract uring stimulation effect andis t he developing t rend of fract uring fluid.Non2damaging f ract uring fluid is an anionic cleanf ract uring fluid which integrates t he characteristics of visco2elastic behavior and anti2shearingand automatic viscosity breaking.It has great advantages such as easy manufact uring,fewadditives,having no residues and little damage.The field applications indicate t hat non2dam2aging fract uring fluid breaks viscosity easily and has low const ructing frictions and st rongcarrying capacity and cont rols f ract ure height effectively.Agreeable field applications showpromising f ut ure of non2damaging f ract uring fluid.K ey w ords:non2damaging;clean f ract uring fluid;anio nic surfactant;evaluation of perform2ance;field applicationsC LC Number:TE357.1+2 Document Code:A0　IntroductionAs an extensively applied contemporary engineering,hydraulic f ract uring has a very p romising f u2 t ure in various fields such as oil p roduction and coal formatio n flooding and eart h st ress measurement and reservoir induced seismicity and dam and side slope destabilizing co nt rol and geot hermal exploitation[1]. Hydraulic f ract uring has been becoming one of t he most important stimulation met hods for t he develop2 ment of low2permeability reservoir where oil production has been greatly advanced by imp roving t he fil2 tering flow co nditions nearby bottom hole.For example,more t han30%crude outp ut in American is obtained by hydraulic f ract uring[2].Fract uring fluid is an essential component part of hydraulic f ract uring project and plays an important role on t he const ructio n work and f ract ure geomet ric shape and f ract uring effect.One of t he mo st valua2 ble index marks to weigh t he f ract uring fluid is t he extent of it s damage to t he formation and t he p ropped f ract ure[3].After years of hard work,non2damaging f ract uring fluid is successf ully developed.This pa2 per st udied it s formula optimization and evaluation of performance.The experiment s indicated t hat non2 damaging f ract uring fluid was manufact ured simply and used few additives and had no residues and broke visco sity easily and had st rong carrying capacity.Moreover,t he field applications gained agreeable re2 sult s.3收稿日期:2008206224作者简介:李林地(1980-),女,河南省南阳市人,在读博士生,研究方向:油气井增产技术基金项目:国家重大课题专项《低渗透油田储层保护与油藏整体压裂改造技术研究》(2007BAB17B03)资助陕西科技大学学报第26卷1　MechanismHydraulic f ract uring is an operation which uses high2pressure p ump group on t he eart h surface to p ump high visco sity f ract uring fluid into well bore at t he delivery rate exceeding t he formation absorba2 bility.Thus,high p ressure will be caused in t he bottom hole.And when it overcomes t he eart h st ress nearby borehole face and reaches t he rock tensile st rengt h,t he f ract ure will be created and will extend forward.In order to avoid t he f ract ure closing after t he high pressure fluid′s flowback,t he carrying fluid is p umped afterwards to extend t he fract ure continuously and to send t he p roppant to t he fract ure.After t hat,high visco sity fluid is broken into low visco sity to ret urn to t he well and t hen flowback to t he eart h surface.As a result,a high conductivity f ract ure remains in t he layer and it is beneficial for oil and gas flow into t he well f rom far distance[4].The main f unctions of f ract uring fluid are creating f ract ure and t ransporting proppant to t he wide2 open fract ure.At p resent,t he most general p urpo se fluid is water soluble polymers wit h cross2linking f ract uring fluid[5].Alt hough it has great sand carrying capacity,t he macromolecules might be adsorbed and left in t he formation pore,which could cause damage to reservoir.Simultaneously,visco sity break2 ing is inadequate and t hen t he residues would seriously decline t he permeability of proppant bed deposi2 tion[6].Schlumberger developed t he visco2elastic surfactant f ract uring fluid(VSE)in1997which is characterized as low f riction and high sand carrying capacity and wit hout solid residues and so on.Thus it has been imp roved quickly in t he past few years[7210].However,t he first generation VSE fluid is cat2 ionic surfactant,while sandstone surface is usually carrying negative elect ricity,so VSE fluid is likely to be adsorbed on sandsto ne surface and it may revise t he wettability and decrease t he size of pore t hroat. Thereby,t he permeability of t he formation nearby f ract ures would be declined.Recently more and more attention is attracted on t hese problems[11].Non2damaging fract uring fluid is an anio nic clean f ract uring fluid which not only inherit s t he advan2 tages of t he first generation V ES fluid but also could avoid t he adsorption on sandstone surface.In a word,it is harmless for t he formatio n and t he p ropped fract ure.2　Formula Optimization ExperimentsAnionic surfactant D3F2AS05is optimized as t he f undamental agent of non2damaging fract uring flu2 id.Besides,KCl and ED TA are chosen as t he anti2swelling agent and t he anti2precipitant.The amount of every co mponent plays a great role on t he performance of non2damaging f ract uring fluid.Formula op2 timization experiment s are shown as following.2.1　Formula ratio of ED TABlend t he formation water from some gas field(degree of mineralization67519.03mg/L,SO422 0.27mg/L,Ca2+12265.28mg/L,Mg2+208.54mg/L)and t he f ract uring fluid(3.0%D3F2AS05+ 6%KCl+0.5%KO H)wit h t he volume ratio of1∶1,t hen add different quantitative ED TA.The ap2 pearances of t he blend fluids are shown as Tab.1.The fluid could prevent t he formation water from scal2 ing if t he amount of ED TA is above0.3%.2.2　Formula ratio of KClT ab.1　Optimization of the amount of E DTAThe amount of ED TA0.1%0.2%0.3%0.4%The appearance of the blend fluid White cloudedfluidMilky whitesemi2opaqueAchromatictransparentAchromatictransparentOn t he basis of t he formula3.0%D3F2AS05+0.3%ED TA+0.5%KO H,consider t he influenceof t he amount of KCl on t he vis2・43・第5期李林地等:无伤害压裂液的研究与应用co sity of t he fract uring fluid.Fig.1shows t hat t he concent ration of KCl in t he system should be be 2tween 6%and 8%.Generally ,t he concent ration of KCl as anti 2swelling agent in t he f ract uring fluid is about 2%.So according to t he work 2load of dispending fluid ,it is better to choo se 6%KCl.Fig.1　The curve of the amount of K Cl influencing Fig.2　The curve of the amount of D3F 2AS05on the viscosity of non 2damaging fracturing influencing on the viscosity of non 2fluid damaging fracturing fluid2.3　Formula ratio of D3F 2AS05On t he basis of t he formula 6%KCl +0.5%KO H +0.3%ED TA ,change t he mass concent ration of D3F 2AS05.Fig.2shows t he visco sity 2temperat ure curves of t he f ract uring fluid.The larger t he mass concentration of D3F 2AS05is ,t he higher capability of it s anti 2temperat ure is.In order to meet t he de 2mand of sand carrying ,t he visco sity of t he f ract uring fluid should be larger 30mPa ・s under 170s 21.So 3%D3F 2AS05is reasonable.Finally ,t he optimized formula of non 2damaging f ract uring fluid is 3.0%D3F 2AS05+0.3%ED TA +6%KCl +0.5%KO H and it s visco sity is 40mPa ・s under air temperat ure and 170s 21.3　Evaluation of PerformanceAdopt oil and nat ural gas professional criterion S Y/T 510721995“The met hod of evaluation of per 2formance of aqueous fract uring fluid ”to do some experiment s to evaluate t he performance of non 2dama 2ging f ract uring fluid such as temperat ure tolerance and anti 2shearing and visco sity breaking and sand car 2rying capability and t he damage to t he formation.3.1　Visco sity 2temperat ure characteristics and anti 2shearing performanceEvaluate t he viscosity 2temperat ure characteristics and t he anti 2shearing performance of non 2dama 2ging f ract uring fluid by means of HA KER visco simeter.It could be seen t hat t here is a high viscosity point at 115℃in Fig.3,so t he optimum temperat ure is between 100℃and 120℃.Fig.4shows t hat t he fluid has a st rong anti 2shearing performance (170s 21).At first t he visco sity drop s because of t he vis 2co sity 2temperat ure effect ,but it maintains steady 20minutes later.3.2　Visco sity breakingperformanceFig.3　The viscosity 2temperature curve of Fig.4　The anti 2shearing perform ance curve ofnon 2dam aging fracturing fluid non 2damaging fracturing fluid・53・陕西科技大学学报第26卷Non 2damaging fract uring fluid could break visco sity by contacting wit h crude oil or diluting forma 2tion water.Blend non 2damaging f ract uring fluid and reagent wit h t he volume ratio of 1∶1,stir t hem at a high speed about one minute and keep t he mixt ure under a constant temperat ure.As shown Tab.2,t he result s indicate t hat non 2damaging fract uring fluid would break visco sity (viscosity is below 5mPa ・s )if it contact s crude oil only one hour later.While wit h formation water (using t he normal saline in t he experiment ,t he compo nent is 70000pp m NaCl +6000pp m CaCl 2+4000pp m MgCl 2)t he viscosity breaking is slower because dilution requires more formation water.The compatibility of non 2damaging f ract uring fluid and t he formation water is good and t here are no residues.Additionally ,non 2damaging f ract uring fluid breaks easily wit h f resh water (tap water ).T ab.2　The viscosity breaking performance ofnon 2damaging fracturing fluidReagentViscosity bre 2ak time/h 40℃viscosity /mPa ・s 80℃viscosity /mPa ・s Crude oil1125Formation water2.52516Fresh water 1.51793.3　Proppant carrying capacity Sufficiently blend 50g ceramsite wit h t he density of 3.31g/cm 3and 100mL non 2damaging fract uring fluid ,and proppant is still suspended after being mixed and kept intact 16h.It shows t hat non 2damaging fract uring fluid has a st rong proppant carry 2ing capacity and it is advantageous to brace t he fract ure evenly after it is clo sed.3.4　Damage experimentConfer oil and nat ural gas professional criterion S Y/T 510722005“t he met hod of evaluation of per 2formance of aqueous fract uring fluid ”to do t he experiment of damage to core at 80℃.The cores come f rom Neopaleozoic reservoir in a gas field.The grain grade gives priority to medium and coarse grain.The content of quartz is between 67%and 90.5%and t he range of feldspar is 0.7%～3.8%.Major li 2t hologic character is lit hic sandstone and lit hic quartz sandsto ne and quartz sandstone.The absolute co n 2tent of clay mineral is very low (≤5.37%).Chief clay mineral is goeschwitzite and kaolinite but wit hout mont morillonite.The content of kaolinite is high (average value is 58.2%).And it is occurred in t he form of inter 2granular filled gat hering but t he disperse state is seldom seen.BXHP G is t he boron cro ss 2linking guanidine f ract uring fluid who se principal ingredient s are 1%KCl +0.45%H P G +0.2%clean up additive DL 210+1%YFP 21foaming agent +0.1%met hanal +0.2%Na 2CO 3+0.05%ammonium persulfate +0.3%cro ss 2linker BCL 261A +20%NaO H.The domi 2nant ingredient of HP G linear gel are 0.3%HP G +1%KCl +0.2%clean up additive +0.1%met hanal +1%foaming agent +0.1%ammonium persulfate.The essential constit uent s of t he first generation V ES fract uring fluid are 3.0%cationic surfactant +2.5%KCl.Tab.3shows t hat non 2damaging f ract u 2ring fluid is nearly harmless to t he core.T ab.3　The damage experiment with different fracturing fluidsFracturingfluidNo.core Core length /cm G as survey permeability /1023μm 2Water survey permeability /1023μm 2Injection rate /PV Water survey permeability after injection /1023μm 2Damage /%BXHP GD4722 5.710.1740.022210.014435.1HP GD4725 6.80.1510.0225 2.50.014933.9V ESD4726 3.780.1190.0213100.018214.6Non 2damaging D47236.730.130.0248100.0244 1.63.5　Visco 2elastic behavior・63・第5期李林地等:无伤害压裂液的研究与应用In fact ,f ract uring fluid is a visco 2elastic fluid.The modulus of energy storage G ′is used to measure t he shearing energy in t he elastic fluid when shearing stress exsites.So G ′is t he yardstick to measure t he elasticity.The modulus of att rition G ″is used to measure t he t hermal energy which is t ranfromed by viscous flowing.So G ″is t he yardstick to measure t he viscosity [12].The weaker t he elasticity is ,t he weaker proppant carrying capacity is.But t he higher t he viscosity is ,t he higher t he f riction is.The re 2search shows t hat it is reasonable to apply G ′/G ″to evaluate t he visco 2elastic behavior of fract uring flu 2id.The best fract uring fluid is one wit h low visco sity and high elasticity.Tab.4shows t hat non 2dama 2ging f ract uring fluid is indeed an excellent fluid.　T ab.4　The comparison of visco 2elastic be 2havior of different fracturing fluids (The ex 2perimental temperature is 90℃and the os 2cillation frequency is 0.1～10H z)Fracturing fluidG ′/Pa G ″/Pa G ′/G ″BXHP G0.80.42V ES8.50.2830.4Non 2damaging 9.80.2539.24　Field Application and ConclusionNon 2damaging f ract uring fluid showed agreeable qualities when it was applied in Daqing Oil Field and Dani 2udi Gas Field and Henan Oil field.For instance ,t he per 2forated intervals of a well in Daqing Oil Field were 2042.6～2040.2m ,2006.6～2003.0m ,1982.2～1980.6m and 1978.621976.2m.It was f ract ured bylayering and back 2reaming.The formation temperat ure was 85℃and viscosity breaker was not used during t he fract uring.Bean up after shutting t he well 3hours ,t he visco sity was broken completely and flow 2back ratio was up to 95%.The p roduction was imp roved from 1t/d to 13.2t/d t hrough t he f ract u 2ring t reat ment using non 2damaging f ract uring fluid.From t he result s of t he f ract uring simulation and well temperat ure test after f ract uring ,it could be seen t hat fract ure height was cont rolled effectively and t he lengt h was eno ugh and it was nearly harmless ,so it was beneficial to broaden oil and gas drainage area and to keep t he production plateau long.Non 2damaging fract uring fluid breaks visco sity co mpletely and has no residues and has strong anti 2shearing capability and good temperat ure tolerance.It also has an excellent proppant carrying capability and low f riction and nearly harmless.Filt ration p roperty is also controlled well and t he capability of flow 2back is excellent.High quality and low damage is t he developing t rend of t he f ract uring fluid.Non 2damaging f ract u 2ring fluid could improve f ract ure flow conductivity and accomplish nearly paring t he water soluble polymers wit h cross 2linking fract uring fluid and t he first generation V ES f ract uring fluid ,non 2damaging f ract uring fluid has a very p romising f ut ure.R eferences[1]J.L.G idley.New Development of t he Techniques of Hydraulic Fracturing[M ].Beijing :Petroleum Industry Press ,2002.[2]J.Shyapobersky ,A.Chudnovsky.Review of recent development in fracture mechanics wit h petroleum engineering applications[C].SPE ,1994:28074.[3]L U Y ong 2jun.Recent advances of 90′s foreign fracturing fluid technology[J ].Chemical Engineering of Oil and Gas ,1998,27(2):1152118.[4]ZHAN G Qi.Theory and Design of Petroleum Engineering[M ].Dongying :University of Petroleum Press ,2000.[5]M.J.Economides.Reservoir Stimulation (Third Edition )[M ].Beijing :Petroleum Industry Press ,2002.[6]WAN G Guo 2lu ,J U Quan 2yi.The damage of water 2based cross 2linked gel fracturing fluid to sandstone formation [J ].OilfieldChemistry ,1986,(3):1492158.[7]G ino Di Lullo ,Atikah bte Ahmad ,Phil Rae ,et al .Toward Zero Damage :New Fluid Point s t he Way[C].SPE ,2001:69453.[8]Mat hew Samuel ,Dan Polson ,Don Graham ,et al .Visco 2elastic Surfactant Fracturing Fluids :applications in low permeability res 2・73・陕西科技大学学报第26卷ervoirs[C].SPE ,2000:60322.[9]Chase B ,Cheilowski W ,Marcinew R ,et al .Clear fracturing fluids for increased well productivity[J ].Oilfield Review ,1997,9(3):20233.[10]L IU Xin 2quan ,YI Ming 2xin ,ZHAO Jin 2ju ,et al .Visco 2elastic surfactant based fracturing fluids[J ].Oilfield Chemistry ,2001,18(3):2732277.[11]CH EN Fu ,L IU Y i ,WAN G Da 2yong.St udies in formation damages caused by cationic surfactant base fracturing fluids[J ].Drill 2ing Fluid &Completion Fluid ,2007,24(6):62265.[12]CON G Lian 2zhu.Preliminary study on t he visco 2elasticity of borate gelling fracturing fluid[J ].Drilling Fluid &Completion Fluid ,1995,12(6):35239.无伤害压裂液的研究与应用李林地,张士诚,张　劲(中国石油大学石油工程教育部重点实验室,北京　102249)摘　要:压裂液作为外来流体进入地层可能会对地层造成不同程度的伤害,减少压裂液对储层的伤害是提高压裂增产效果的重要前提,也是压裂液发展的方向.对压裂液多年研究的基础上,开发成功了无伤害压裂淮,该压裂液是一种阴离子型清洁压裂液,集粘弹性、抗剪切性、自动破胶性于一体,具有配制简便、使用添加剂种类少、不存在残渣、对储层伤害小等特点.现场试验表明,无伤害压裂液易破胶,施工摩阻低,携砂能力强,可有效地控制缝高,压裂施工后增产效果明显,有着广阔的发展前景.关键词:无伤害;清洁压裂液;阴离子表面活性剂;性能评价;现场应用中图分类号:TE357.1+2 文献标识码:A(上接第5页)[9]Valdek Mikli ,Helmo Kaerdi ,Priit K.Characterization of powder particle morphology[J ].Proc.Estonian Acad.Sci.Eng.,2001,7(1):22234.[10]Anne Skriver ,Martin B.Hansen ,Karsten B.Q.Image analysis applied to elect ron micrographs of stirred yogurt [J ].Journal ofDairy Research ,1997,64:1352143.合成纤维成纸横截面SEM 图像量化分析张素风,张美云(陕西科技大学造纸工程学院,陕西西安　710021)摘　要:将Image J 程序应用于合成纤维成纸横截面SEM 图像的量化分析.对随意选取的合成纸横截面的一个SEM 图像计算了纸张z 向结构的纤维直径和纤维形状因子,分析并估算了纸张结构中的孔隙分布和浆料配比.试验采用的试样纸中合成纤维直径范围为14.10～20.38μm ,平均直径为17.37μm ;纤维形状因子为1.57～3.0,平均值为1.97;纸张的孔隙率为11.59%,纸张成形匀度很好,孔隙分布也比较均匀;图片中纸张反映出两种纤维配比为1∶1.研究结果表明使用该方法对同一样品的多张不同图片进行统计分析,可以得到可靠的浆料配比数据.关键词:SEM 图像;合成纤维纸;孔隙分布;纤维直径;纤维配比中图分类号:TS71+.2;TP391.41 文献标识码:A・83・。