杏平1水平分支井钻井液技术

文章编号:1001 5620(2007)02 0015 04

杏平1水平分支井钻井液技术

蔺志鹏 陈恩让 胡祖彪 高洁 谭海嵘

(长庆石油勘探局工程技术研究院,陕西西安)

摘要 杏平1井为一口多分支(7分支)水平井。为了该井的顺利完成和对低压低渗透油层的保护,研究应用了低摩阻、低伤害无固相钻井液。现场应用证实,该体系有效控制了易塌层直罗组、富县组和煤层、炭质泥岩的井壁坍塌,在主水平井段钻完后静止浸泡达6d 的情况下顺利下钻;钻井液性能稳定,A P I 滤失量可控制在2mL 以内,3.5M Pa 、60 下的滤失量不大于20mL ,对水基无固相钻井液滤失量的有效控制进行了一次成功的尝试;钻井液润滑系数为0.065~0.15,摩阻扭矩小,井壁稳定,为长水平井段多分支井的顺利钻进提供了安全保证,水平及分支井段平均机械钻速达到6.84m /h;该钻井液无初失水,滤饼渗透率低,p H 值小于8.5,滤液对杏河区块长6油层岩心的伤害率小于20%,渗透率恢复值达到70%。

关键词 分支水平井 水基钻井液 无固相钻井液 钻井液性能 储集层 地层损害 现场试验中图分类号:T E254.3

文献标识码:A

1 工程概况

杏平1井是长庆油田第一口多分支水平井,其目的是增加低压低渗透油藏最大储层有效进尺,用分支代替压裂造缝,增大油井的泄油面积,提高单井产量和采收率。该井位于安塞油田西南部的杏河区块东北,目的层为长6油层,油层埋藏1350多m,于2006年5月1日开钻,8月10日完钻。完成钻井进尺5068m,主水平井眼长1203m,水平位移为1574m,比垂深多214m ,是垂直井深的1.16倍。完成与主水平井眼成30 ~40 的水平夹角、长300~422m 的7个分支井眼(如图1所示),水平井眼总进尺为3503m 。井身结构见表1

。

图1 杏平1井水平投影图

2 一开、二开钻井液技术

该水平分支井一开使用膨润土浆开钻。二开到

表1 杏平1井井身结构

钻井井段钻头mm 井深m 方位( )

井斜角( )备注

一开444.50~1570二开311.1

157~1000

995~1565

111090直井段斜井段三开215.91565~1806111~115

88~92

主水平井段1706~20261123~7886~92第二分支井段1806~2768111~11588~92

主水平井段

2308~2625111~14788~91第七分支井段2182~2482

112~76

88~92第六分支井段2036~2458112~14788~90第五分支井段1938~2238112~15085~92第四分支井段1820~2161112~14686~93第三分支井段1588~1888112~147

87~93第一分支井段

注:一开 339.7mm 套管下至井深157m ,二开 244.5mm 技术套管下至窗口(井深1561m),三开水平及分支井眼

注原油裸眼完井。

小斜度井段使用强抑制无固相聚合物钻井液,

控制钻井液密度为1.01~ 1.02g/cm 3,漏斗黏度为29~38s,滤失量为不控~15mL ;大斜度井段到窗

第一作者简介:蔺志鹏,高级工程师,1986年毕业于西南石油学院开发系应用化学专业,现在长庆石油勘探局工程技术

研究院钻井液完井液研究所工作。地址:西安市兴隆园小区工程技术研究院;邮政编码710021;电话(029)86596597。

第24卷第2期 钻 井 液 与 完 井 液 Vo l.24No.22007年3月 DRILLING FLUID &COMPLET ION FLU ID M ar.2007

口使用低摩阻低固相聚合物钻井液,控制钻井液密度为1.04~ 1.14g/cm3,漏斗黏度为40~50s,API 滤失量不大于6mL,pH值为9.5~10.0。

3 水平及分支井段无固相钻井液技术3.1 低摩阻、低伤害无固相钻井液体系

应用于水平井的水基钻井液必须具备2个条件。一是确保钻井工程施工的安全和尽快的速度,二是尽可能降低对产层的伤害,对于分支水平井更是如此。杏平1分支水平井属低压低渗透油藏,压力系数为0.7~0.8,渗透率为0.6!10-3~0.8! 10-3 m2,而且在钻井施工中油层暴露面积大,浸泡时间长,如何减少钻井完井液对油层的伤害是钻井液技术首先要考虑的问题。此外,该井水平井段和分支井段长且多,井眼成三维结构,钻具在井内的摩阻、扭矩必然增大,如何使钻井液润滑性能达到最优,降低摩阻、扭矩,是该水平分支井能否顺利完成的关键技术之一,也是水基钻井液技术的关键所在。

安塞油田低压低渗透油层保护技术研究结果表明,钻井液固相及处理剂对油层有伤害,其中高分散固相、碱及高分子量聚合物对油层的伤害较大。因此,针对以上技术难点,并根据该分支水平井完成后无法进行后期改造的情况,研究出了低摩阻、低伤害无固相钻井液体系。其室内基本配方性能:密度为1.01g/cm3,API滤失量小于5.0mL/30min,pH 值为7~8,表观黏度为20~40mPa?s,塑性黏度为15~25mPa?s,动切力为8~15Pa,动塑比为0.4~ 0.6Pa/m Pa?s,岩心伤害率小于20%,钻井液摩阻系数(EP极压润滑仪测得)小于0.1。低摩阻、低伤害无固相钻井液的主要特点是无固相、滤失量低,润滑性良好,对储层伤害小。

3.2 控制滤失量技术

该钻井液是在清水中加入试验优选的处理剂形成的,而且以在清水中能有效控制滤失量的处理剂为主体。如在清水中加入H DF 1、FL 1、GF 1等所形成的体系,在3.5MPa、60 条件下的滤失量也只有17mL。该体系实现低滤失量的主要原因是,它在压差作用下可快速在滤纸表面(或井壁岩石表面)形成致密低渗透层,阻止钻井液及其滤液渗透到地层中,而不是单纯依靠处理剂控制自由水达到低滤失量的目的,具有近似于超低渗透钻井液的性质。因此该钻井液基本无初失水。3.3 降低储层伤害技术

低摩阻、低伤害无固相钻井液主要从以下几方面减少对油层的伤害:#低滤失,并在井壁岩石表面形成低渗透层,阻止外来物质进入油层;?低渗透层形成速度快且薄,一旦有反向压力,容易被清除,杏河油区长6油层岩心的渗透率恢复值大于80%(见表2);%无固相,低密度;&控制低碱度(pH值小于8.5)及含有小分子有机阳离子抑制剂等使滤液性质有利于保护油层。同时,杏平1分支水平井每完成一水平井段施工,在井眼内注入原油保护油层,由于原油对储层基本无伤害,且它的渗透性强,也可破坏在井壁上形成的低渗透层,实现油层解堵。

表2 岩心伤害评价试验(杏70 6井长61油层岩心)

岩心号

K a!103

m2%

K o1!103

m2

K o2!103

m2

伤害率

%

损害

程度1 22/33 20.95610.470.1990.164517.34低伤害1 24/33 20.68810.040.1180.094519.85

1 26/33 10.58610.520.0870.073215.86

2 43/152 20.2948.890.0320.027115.31

3.4 降摩阻降扭矩技术

该钻井液选用了润滑效果与油基钻井液相当的润滑剂。在室内测得的清水、4%水化膨润土浆、原油、油基钻井液和低摩阻、低伤害无固相体系的润滑系数分别为0.34、0.5、0.023、0.08和0.032。

4 现场应用及效果

4.1 施工工艺

在应用过程中的处理与维护始终以保护油层和提高润滑性能为考虑点。钻井液应用配方如下。

清水+(0.5%~1%)H DF 1降滤失剂+1% FL 1无固相降滤失剂+(0.2%~0.3%)PAC H V 增黏剂+1%GF 1含硅类防塌剂+(0.3%~0.5%) CWD 1阳离子粘土稳定剂+(0.5%~1%)RT 988极压润滑剂

1)三开前在地面循环罐(清理干净)中按照配方使用配浆漏斗加入各种处理剂(先不加入润滑剂),充分搅拌,小循环,使其形成体系,以中压滤失量不大于5mL为配制合格标准。待技术套管水泥塞钻完后,用配制的三开无固相钻井液将井内钻井液替出、放掉,开始三开主水平井段钻进。

16 钻 井 液 与 完 井 液 2007年3月

2)钻进过程中,按应用配方补充钻井液减少量;以加入PAC H V 量的多少调整黏度;加入CWD 1控制地层中泥质成分造浆及抑制油层孔隙中充填物水化膨胀分散。

3)随着水平井段的增长,加入润滑剂,增加钻井液的润滑性能,降低摩阻。

4)充分使用除砂器和离心机,控制钻井液密度、含砂量上升。

图2~图8是主水平和分支井段钻井液性能控

制情况。

图2

水平井段钻井液密度变化

图3

水平井段钻井液漏斗黏度变化

图4

水平井段钻井液滤失量变化

图5 水平井段钻井液润滑系数变化

4.2 应用效果

低摩阻、低伤害无固相钻井液在该井井深1203

图6 水平井段钻井液pH 值变化

图7 水平井段钻井液黏度变化

图8 水平井段钻井液动切力变化

m 主水平井眼和7个分支井眼(进尺2300m )的应

用是该体系的第一次现场应用,也是长庆油田第一次使用水基无固相钻井液钻开油层。

1)润滑性能良好。EP 润滑仪测得的钻井液润滑系数为0.065~0.15,钻具在井眼内的摩阻、扭矩小(见表3),调整轨迹滑动钻进时加压正常,确保了长水平及分支井眼的顺利完成。同时具有良好的防黏卡性能,分支侧钻过程中钻具大面积接触井壁,长时间近似静止,但无阻卡现象。

表3 水平及分支井眼摩阻扭矩数据

井眼水平段长m 分支长

m 方位( )上提摩阻kN 扭矩kN ?m 主水平1203111~11520010~14第二分支461320113~781208第七分支1087317111~147200~2108~14第六分支

917300112~761608~12第五分支893422112~14780~9010~11第四分支673300112~758010~11第三分支596341112~14660~10010~1117

第24卷第2期 蔺志鹏等:杏平1水平分支井钻井液技术

2)滤失量很小。现场API滤失量在2mL以内,3.5MPa、60 条件下的滤失量也不大于20 mL,且无初失水,滤饼渗透率低(见表4),这说明该钻井完井液在压差作用下可在滤纸(或岩石)表面快速形成一层低渗透薄膜,阻止滤液滤失。

表4 杏平1水平分支井现场钻井液滤失性能

A PI

滤失性能

滤失量/(mL/30min)

滤过水量/(mL/30min)

滤饼渗透率(清水测30min), m2

2.9

2.5

1.3!10-7

60 、3.5M Pa

滤失性能

滤失量/(mL/30min)滤过水量/(mL/30min)

滤饼渗透率(清水测30min), m2

20

10 1.02!10-6

同时体系无固相,尤其是无高分散性固相,密度低,且碱度低(pH值在7.5左右)及含有小阳离子抑制剂和含硅类处理剂,滤液性能有利于控制油层孔隙中的填充物膨胀、分散和运移;淀粉类处理剂参与滤饼形成,其随时间的自降解性能可使滤饼破坏,有利于解除油层表面的封堵。岩心评价结果表明,杏河区块长6油层岩心的伤害渗透率恢复值达到70%。另外,杏平1井每完成一井段施工,在井眼内注入原油保护井眼,由于原油的渗透性强,使井壁上滤饼破坏,使油层解堵。如表5所示。

表5 杏平1井现场钻井完井液的岩心(长61)伤害评价

岩心号井号K a!103

m2%

K o1!103

m2

K o2!103

m2

伤害率

%

1 38/119 2*杏21 0120.66613.770.056450.0418325.90 1 26/33 2*杏70 60.92911.520.20290.142929.57

1 28/33 2*杏70 60.64611.050.10050.0714128.95

2 39/15

3 2**杏70 6 1.0411.450.047920.044068.06 2 39/152 3**杏70 6 1.0311.740.054680.0446718.31 注:*用现场完井液伤害,**用现场完井液一次伤害,原油二次伤害。

3)钻井液性能稳定。长时间循环(高速剪切和温度作用下)期间漏斗黏度基本保持为40~45s,切力适当(静切力为0.5/1~ 1.5Pa、动切力为1.5~ 2.5Pa),在机械钻速为13~15m/h的情况下,能够满足该地层水平井带砂的要求。

4)井壁稳定性强。主水平井眼从井深2440m 开始,钻遇大段炭质泥岩及煤层。钻井液满足了高钻屑浓度的井眼清洁,也有效控制了炭质泥岩和煤层的坍塌,其主要原因是在钻井液液柱产生压力平衡的同时,#滤失量小,侵入煤层和炭质泥岩缝隙的钻井液滤液少;?在新的井眼形成的同时,在压差作用下钻井液快速在微缝隙中形成低渗透层堵塞,一是阻止滤失,二是有加固井壁的作用。在主水平井段钻完后,进行电测、钻具探伤、设备整改等,静置浸泡长达6d,下钻顺利通过炭质泥岩和煤层井段,更进一步说明炭质泥岩和煤层井眼是稳定的。

5)机械钻速快。无固相及良好流变性有利于机械钻速的提高。水平及分支井段平均机械钻速达6.84m/h,其中1203m水平井段平均机械钻速达到6.57m/h,三维的分支井眼平均机械钻速最高达到8.93m/h。

4 几点认识

1 室内试验及在杏平1井的现场应用初步表明,研制出的低摩阻、低伤害无固相钻井液的组成简单及应用工艺简单,无特殊施工要求,只要按配方配制及维护,就能调整好性能参数。尤其钻井液滤失量很低,为水基无固相钻井液有效控制滤失进行了一次成功的尝试。

2 该钻井液具有良好的的润滑性能和控制泥页岩坍塌的能力,钻进中摩阻扭矩小,也为水平井眼的有效净化提供了良好的井眼基础,井下安全。

3 该钻井液以降低和严格控制滤失量为基础,从体系组成、性能控制等方面表现出其有利于油层保护,室内初步评定其对储层岩心的伤害为低伤害。

4 从该体系在使用中的性能变化来看,要有效控制密度和含砂量,应配备更有效的固控设备。

(收稿日期2006 10 09;HG F=072W3;编辑 汪桂娟)

18 钻 井 液 与 完 井 液 2007年3月

84 DRILLING FLU ID&COM PLET ION FLU ID M ar.2007

First author?s address Drilling Fluid Service Com pany of CNPC Xinjiang Petro leum,Karamay834009,Chi na

Laboratory Studies on Water Base Polymer sulfonate Muds W eighted with Manganese Tetraoxide.DFCF, 2007,24(2):11 12

Authors ZH EN G Li hui,ZH ANG Li bo,WEI Zhi lin

Abstract T he overseas field applicatio n show s that oil base m uds w ith densities greater than1.6g/cm3have low er equivalent cir culation density(ECD)if manganese tetraoxide is used as the w eighting ag ent,instead of bar ite.Six thro ug h tubing slim ho le w ells have been successfully completed.Po lymer sulfo nate w ater base m uds w ere weighted w ith hausmannite,barite,ultr a fine calcium carbo nate and iro n o r pow der re spectively,to density o f1.6g/cm3,and the apparent viscosity and plastic viscosity of the fo ur w eighted muds w ere measured betw een densities fro m1.2 1.6g/cm3for5density data points.T he change of the apparent viscosity and plastic viscosity w ith mud density was analyzed.ECDs w ere calculated at a w ell depth of4150m for these muds,and the results show ed that w hen mud density is greater than1.46 g/cm3,low er ECD can be obtained using hausmannite.

Key words drilling fluid additives;m ang anese tetraox ide;w eighting materials;dr illing fluids;equivalent circulation densities

First author?s address College of Oil and Gas Eng ineering,Univer sity of Petroleum,Beijing102249,China

Filtration Reducing Performance and Working Mechanism of Rap Oil Seedcakes.DFCF,2007,24(2):13 14, 36

Authors H U ANG Xue jing,CUI M ao rong,MA Yong,ZH OU Chang hong,BAI Li ye

Abstract T he major components of the rap oil seedcakes are protein,nitro gen fr ee lixivium,coarse fiber, crude fats,and ash content.T hese co mponents have g ood filtr ation r eductio n in drilling fluids.M odifica tion w as done to rap oil seedcake in an effor t to m ake the best use of it.T he solubility and dispersion of the modified rasp o il seedcake in drilling fluids w as g reatly im pro boratory evaluation was done on the modified product,CYL.It is show n that less amount o f CYL is needed in filtration co ntro l.Mud cake gen erated by the CYL treated mud is thin and tough.CYL can be used at elevated temperatures,and in salt w ater m ud o r w ater base m uds co ntaining a certain level of calcium.CYL also has lubr ication ability be cause it is made fr om rap oil.In one w ord,CYL is a superior,cheap filtratio n reducer in w ater base muds. Key words w ater base muds;m ud additives;filtrate r educer;rap o il seedcake

First author?s address Southw est Petr oleum U niversity,Nancho ng637001,China

Horizontal Multi lateral Drilling Fluid Technology:W ell Xingping 1.DFCF,2007,24(2):15 18

Authors LIN Zhi peng,CH EN En rang,H U Zu biao,GAO Jie,TAN H ai rong

Abstract Well Xing ping 1is a horizontal multi lateral(7laterals)w ell.Low drag so lids free dr illing fluid w as used to drill this long horizo ntal displacement w ell successfully and to pro tect the low pressure low permeability r eserv oir from being damaged.Field practice show s that the m ud used effectively stabilized the heaving Zhiluo and Fuxian fo rmations and coal beds,carboniferous mudsto nes.T rip in w as done smo othly in the horizontal sectio n ev en after6days during w hich m ud circulation had been stopped.A PI filter lo ss could be m aintained at less than2m L and filter loss measured at3.5M Pa and60 w as not greater than20mL.T he friction coefficient w as less than0.15,w ith a m inimum of0.065.Drag and to rque w er e low and bo re hole stability w as impr oved using this m ud.The average ROP in horizontal and

lateral sections w ere up to 6.84m/h.T his mud had no spurt w ater loss and the per meability of the m ud cake w a low.T he pH o f the mud w as less than 8.5.Lo w m olecular w eig ht cationic po lymer and silicon ad ditive in the mud g reatly enhanced its performance in the application in horizontal multi lateral wells.Per m eability test o n a cor e fro m Well Chang 6sho w ed that the co re perm eability damag e w as less than 20%,and the permeability recov ery w as 70%.

Key words multi later al horizontal w ells;w ater base muds;so lids fr ee drilling fluids;performance of the drilling fluid;reservo ir beds;formation dam ag e;field tests

First author ?s address Research Institute of Engineering Technolo gy,Chang qing Petro leum Explor ation Bureau,Xi'a n 710021,China

Researches on Polyelectrolyte Drilling Fluids.DFCF ,2007,24(2):19 22

Authors LIU T ao g uang,WU H ong yu,LI Bin,BA I Wen kai,LIU Jing li,MA H ong quan

Abstract Research was done on an inhibitive w ater base mud w ith go od sealing capacity to replace the ex pensive w hite o il base mud used in the Bei 80area,in w hich the reservoir is strongly w ater sensitive.A po lyelectrolyte w as selected to use in 40%w ith other com patible additives,and a set of w ater base muds w ith ex cellent mud proper ties w as bo rato ry r esearch show s that reservoirs dr illed w ith poly electro lyte mud have permeability r ecovery even hig her than that of reservo ir s drilled diesel oil base muds,only slightly less than that of reserv oirs drilled w ith w hite o il base m uds.Polyelectro lyte mud has stro ng inhibition and g ood m ud cake form ing ability.The Rheolo gy of the mud is easy to contro l.T his m ud also has g ood co ntamination resistence,and can be used at elev ated temperatur es.It is com parable w ith oil base muds in hale inhibition and r eser voir protection,and can satisfy the needs fo r drilling in Bei 80area.Key words polyelectroly te drilling fluid;stro ng ly w ater sensitiv e r eserv oir;inhibitio n;for matio n damage prevention

First author ?s address Dr illing fluid serv ice com pany of CNPC Xinjiang Petroleum,Karamay 643009,China Laboratory Studies on Positively Charged Poly Alcohol Drilling Fluids.DFCF ,2007,24(2):23 25Authors LIU Jin hua,YAN Jie nian

Abstract T he po sitiv ely charged poly alcohol dr illing fluid is a new drilling fluid originated from the poly al cohol drilling fluids.The po sitiv ely charged poly alcohols have molecular gr oups that are hydr ophilic at low temperatures and hydropho bic at elev ated tem peratur es.The temper ature at w hich the positively charg ed po ly alcohol turns fro m hy drophilic to hydr ophobic is called the cloud point of the alcohol.T he po sitiv ely charged po ly alcohols hav e strong inhibitiv e capacity to sales and are environmentally friendly.A mud for m ulation containing po sitively charg ed poly alcoho ls w as developed through careful selection o f mud addi bo rato ry studies show that this fo rmulatio n has low er filtration r ate,higher inhibitiv e capacity and better lubricity,com pared w ith o ther w ater base bor ator y resear ches were also done on the investig ation of the w orking mechanism o f the m ud,and show ed that the positiv ely charg ed po ly alcohols have synergistic functions w ith o ther mud additiv es.Bo re hole can be easily and effectively cleaned using this mud.Bore hole stability is achieved and frictio n coefficient of the mud is low.

Key words po sitiv ely charg ed poly alco ho l drilling fluids;w ater base muds;filtratio n reduction;bo re hole stabilization;lubricity

First author ?s address Department of Drilling,Petro leum Ex plor ation and Dev elo pment,Petr ol China,Dezhou 253005,China

85Vo l.24,No.2 ABSTRA CT