一种保持大斜度定向井井眼清洁的有效技术

1、一种保持大斜度定向井井眼清洁的有效技术王爱宽1高虎2邵晓伟2张晓凯3杜丽3(11中原石油勘探局钻井一公司21中原油田分公司信息中心31中原油田分公司采油二厂摘要为了提高大斜度定向井的施工安全,钻井过程中及时清除岩屑床,研究出了一种射流除屑剂。该除屑剂的施工要求为:密度比基液高014015g/cm3,在环空中至少有61 122m,除屑过程中必须保持连续开泵循环,采用正常排量循环除屑,钻具转速应为80r/min 左右。,应使用34次除屑剂清砂。使用该除屑剂清砂作为预防措施时,每68h或钻进150300m进行一次清砂。现场实践表明:应用该除屑剂能有效清除大斜度井段的岩屑,避免岩屑床的形成,保证大斜度

2、定向井的施工安全。关键词大斜度定向井岩屑床射流除屑剂井眼清洁技术引言在大斜度定向井的施工过程中,由于井眼得不到及时清洁,钻井事故时有发生。岩屑床的形成,往往导致转动钻具时扭矩增加,钻具上提遇卡下放遇阻,甚至造成压差卡钻等复杂情况,及时的清洁井眼就显得尤为重要。在不断的实践与研究过程中,国内外专家对井眼清洁问题都做出了艰苦卓绝的努力。陈乐亮1对井眼净化进行了细致的研究,黄丽萍2提出了机械法清除岩屑床,胡景荣3针对大斜度定向井的井眼净化问题,提出了“融钻进与清除岩屑床为一体”的作业工艺设想。基于这一思路,研究出了一种与钻井施工为一体的射流除屑剂。传统除屑方法在长裸眼井段的大斜度井中,总是达不到预期

3、的效果。应用射流除屑剂的方法清除堆积在下井壁的岩屑床,改变了过去清除岩屑的模式。研究表明,应用稀钻井液产生紊流,清除岩屑床的效果远比稠钻井液有效4。1旧模式的不足钻井过程中井眼得不到很好的清洁时,最先考虑的往往是排量和钻井液粘度是否合适,实际上钻井液的流变性是至关重要的因素。很多传统的模式建立在“平均环空流速”基础之上,这种模式仅适用于直井和定向井的直井段,因为在这些井型中,钻井液的流变性始终保持一致,但不适用于造斜点以下的定向井段。在定向井段钻柱轴线偏离井眼轴线,其偏离程度随井斜角的增大而增大,最终与井眼低边接触,沿(或逼近井眼低边移动或滚动。现场实践表明:由于钻具偏心造成的钻井液流变性的变

4、化,成为考虑井眼清洁时更重要的参数。钻具的偏心度极大地影响钻井液的理论流变性5。以往在油田现场广泛使用幂律模式和宾汉弹性模式。如今电子计算机的出现使运用更复杂的Herschel-Bulkley模式成为可能6。尽管后者计算结果比较精确,能够很好的适用于滑动钻进,但不能很好地适用于钻具旋转状态。幂律模式没有考虑凝胶强度或低剪切速率应力,故比较适合于钻具旋转状态。2射流除屑剂的组成和特点组成:取自施工中所用钻井液,并保持原有的屈服值。采用比原钻井液较低的合适粘度,所需值可通过加水和膨润土调整。特点:密度较高,往往比原钻井液高01477断块油气田第10卷第5期FAUL T2BLOCK OIL&

5、GAS FIELD2003年9月收稿日期2003-02-21第一作者简介王爱宽,1966年生,工程师,1990年毕业于西南石油学院钻井工程专业,现从事钻井工程技术工作,地址(457331:河南省清丰县,电话:(03934807724。015g/cm3。足够的量,在环空中至少有61 122m。除屑过程中,必须保持连续开泵循环,在除屑剂返至地面前不得中途停泵。采用正常排量循环除屑,钻具转速应为80r/min左右,一旦除屑剂到达井底并返至地面,将会携带出可观数量的岩屑,使井眼情况得到根本性好转。3射流除屑剂的施工要求射流除屑剂的密度要比基液高出014015 g/cm3,并在环空占据60120m,产生

6、350kPa 的静液柱压力。基浆必须具有好的流变性和较小的失水量。如果基浆失水量大,其流变性很差,井眼不但不能很好地清洁反而可能恶化。泵入除屑剂时,一般要求排量稍微降低(12 13L/s。如果返出除屑剂的密度增加不到0106 g/cm3,则所配密度较低或用量不足。当用较稠基浆配制除屑剂时,需稍微提高密度差值。射流除屑剂除砂应作为预防措施经常使用,尤其在大斜度定向井中,应该综合考虑滑动钻进和旋转钻进时的不同情况,合理运用除屑剂来达到最佳效果。当除屑剂循环至振动筛时,振动筛布的尺寸大小影响被除岩屑的数量。应用210目的筛布能满足施工要求。4影响射流除屑剂的因素411粘度常规钻井中,当井斜超过30&

7、#176;,膨润土开始沉淀,在无油气侵和水侵等情况下,返出的钻井液密度将低于泵入的钻井液密度。往往采取的钻井液补救措施是:提高低剪切速率流变参数(三速、六速范氏粘度计读数,提高钻井液粘度,屈服值也从29134818kg/m2提高到14615kg/m2。粘度较高的钻井液,井眼清洁效率高。但上井壁处的过度冲刷意味着下井壁处更为缓慢的流动,甚至加速了岩屑床的堆积和形成。旋转钻进时,钻具靠近下井壁的钻井液流动是很缓慢的。因为钻井液的流动总是沿着最小阻力的路径,钻井液粘度的升高总能加剧上井壁和下井壁处钻井液流动的差异,使井眼清洁变得更为困难。射流除屑剂具有完全不同的效果,能够在环空形成异常的射流,从而很

8、好地清除下井壁的岩屑。密度的差异、重力的作用加之钻具旋转阻力等因素,造成该射流从环空的狭窄段流动从而清理下井壁。另外,密度的提高也增加了钻井液的浮力,有助于从井眼中携砂。412转速钻具转速是影响携屑效果的一个重要因素。要使射流除屑剂达到预期的理想效果,在整个除屑过程中,钻具应当不停地转动,并且不得中途停泵。增加转速在 100120r/min和150180r/ min两个范围段,能够收到很显著的携屑效果(见图1。但在高转速范围段,转速越增加,携屑效果增加越不明显5。在定向井施工中,定向工具往往要求转速为6080r/min。这就使得通过提高转速来获得较佳除屑效果的做法变得不可取。虽然单纯增加转速能

9、够提高钻屑携带效果,但不能有效地防止和清除在下井壁的岩屑床。反之,用射流除屑剂在正常转速范围下循环清砂则能达到理想的除屑效果。图1钻具转速的影响413滑动钻进和盲区滑动钻进时,就会产生一些盲区(岩屑区。因为在绝大多数定向井中滑动钻进是不可避免的,故研究岩屑床的动态变化显得极为关键。滑动钻进时,相当长的一段钻柱要接触井眼下井壁,甚至在最理想的钻井液流型时也存在这种情况。接单根和起下钻时,一些数量的膨润土和较细的岩屑将会堆积在下井壁。改进型岩屑运移模式,给出了最优化的流变参数和钻具转速,能够计算多种除屑剂携带正常钻屑的能力(见图2。5应用实例Newfield勘探公司的West cameron井,井

10、斜达到55°,并进行了120°的左向扭方位,钻达设计井深时预计扭矩为3017kNm。在实际施工过872003年9月断块油气田第10卷第5期程中,没有采用常规的稠钻井液携砂剂,也没有在钻井液中补充润滑剂和固体滚珠,而是采用这种射流除屑剂,实际最高扭矩仅为2014kN m ,清洁井眼状况达到了历史上的最好水平(见图3 。图2携砂效率对比(携砂效率为0代表正常钻进时的状况 图3射流除屑剂在We st cameron 井中的应用在West cameron 井第一次试验射流除屑剂时,该井使用油基钻井液,第一次除屑量达到了2154m 3,以后的除屑量分别为每次01641191m 3不等

11、。使用该除屑剂清砂后,钻进过程中没有出现以往的旋转扭矩大、缩径点多等难题。在另一口海湾地区的钻井中,以往的钻进水力模式预测<17718mm 井眼钻至1768m 、井斜为40°时将会发生严重的井眼清洁问题。当滑动钻进时,射流除屑剂被泵入井内除砂。但在测斜和短下钻前没有完全循环到地面,当短起至1707m 时,遇到了多处缩径点,不得不采取倒划眼,憋泵现象时有发生。经分析认为,此次复杂是由于斜井段井的岩屑床所致。6建议a 计算射流除屑剂所占的环空高度和增加的环空静液柱压力。b 清砂时,钻具转速为80r/min ,但180r/min 为首选。当滑动钻进时,建议不采用该除屑剂清砂。c 保持

12、连续循环直至除屑剂返至地面,如在定向井段中途停泵时,将不会产生射流,所除掉的岩屑床会很快重新堆积。d 避免提高除屑剂的粘度。e 当出现井眼清洁问题时,建议使用34次除屑剂先后清砂,一次清砂可能起不到很理想的效果。f 使用该除屑剂清砂作为预防措施时,每68h 或钻进150300m ,进行一次清砂,因为岩屑床的堆积形成与钻进时间和进尺有很大关系。起钻前或下钻到底后,使用该除屑剂清砂。g 射流除屑剂并不能根除大扭矩、大摩阻等有关井眼清洁问题。一口井的合理、正确的设计才是避免这类难题的第一要素。参考文献1陈乐亮.水平井的井眼净化问题.钻井液与完井液,1992,9(32黄丽萍.机械法清除岩屑床的探讨.钻

13、采工艺,2002,25(3:223胡景荣.再论大斜度定向井的井眼净化问题.钻采工艺,2001,24(2:144Azar J ,Pilehvari A and Shizari S.State of the Art CuttingsTtransportinHorizontal Wellbores.SPEDrillingandCompletion ,1999,14(3:1961995Krepp A.Hole Cleaning in ER Wells :It s not the Mud Man s Job.Drilling &Well Performance Technology Newsle

14、tter ,4th Quarter 1999.676Sewell Mike and Billingsley Joe.An Effective Approach toKeeping the Hole Clean in High -Angle Wells.World Oil ,2002,223(10(编辑赵卫红97第10卷第5期王爱宽等1一种保持大斜度定向井井眼清洁的有效技术2003年9月An E ffective T echnology of K eeping the H ole Clean in High2angle WellW ang Aiku an(N o.1Drilling Compan

15、y,Zhongyu an Petroleum Exploration Bureau,SIN OPEC,H enan457331, P.R.China,G ao H u and Shao Xiaow ei et al.F ault2B lock Oil&G as Field,2003,10(5:7779A kind of effective weighted sweep,has been studied and applied to timely remove silt bed accumulating on the low side of the hole,thus high2angl

16、e directional well can be drilled successfully and smoothly.The requirements of the weighted sweep include:being014015g/cm3higher than the mud density,spaning60120m in the annulus,keeping pumping continually until the sweep is out of the hole, normal flowrate are80rpm.If the hole2clean problem is su

17、spected,it can achieve desired results to run34sweeps. If desired for preventive measure,the sweep should be put into use regularly every68h or150300m.The application on site show that this kind of sweep can clear away cutting and silt in the high2angle intervals,avoid the silt bed,make the downhole

18、 condition safely and desirablely.K ey Words:High2angle directional well,Silt bed, Weighted sweep,Hole clean,Technology.The Workover T echnique of High Pressure Oil2gas Well S296Zhang Wenzhong(Drilling Department,Jiangsu Oilf ield,SIN OPEC,Jiangsu225261,P.R.Chinaand Feng H uibin.F ault2B lock Oil&am

19、p;G as Field,2003,10(5:8081S296well is a high pressure oil2gas well which contains H2S gas.The target bed lies in the Ordovician system, crack and solution cavity grow in the formation.Passing by acid2fracture again,its difficult to find out a fitly kill mud density to prevent lost circulation or oi

20、l2gas from channel in workover.Controlling oil2gas is the premise job of the safe workover.Many working procedure in workover did not achieve the purpose of the design.At first,run in plug but did not work,then run in permanent bridge plug.The bridge plug were stabbed bad by high pressure oil2gas.Af

21、ter pour the ash with electric cable,have no the cement plug on the bridge plug.Finally throw the gravel into the well,put sand into the well,and pour the ash,waiting on cement with suppress,at last block off the bottom high pressure bed.From all over the workover process,all of the tool and down2ho

22、le completion system should be researched and tested far way whether to suit high pressure oil2gas well.S296well workover job provides the experience for other high pressure oil2gas well.K ey Words:High pressure well,Ordovician,Lost circulation,Blowout,K ill mud,Plug,Bridge plug.High E nergy Multipl

23、e Pulse Overb alanced Perforating T echniqueZhang Jie(Xian Petroleum I nstitute,Shanxi710065, P.R.China,X ue Zhongtian and Liao H ongw ei et al.F ault2 B lock Oil&G as Field,2003,10(5:8283High energy multiple pulse overbalanced perforating is a new perforating and stimulation technique which use

24、s high energy fuels burning to produce pressure in interest formation.This paper presents the basic principle and equipments design,gives some examples of the techniques use in our country.The examples show the technique is very good in completion and stimulation.K ey Words:Multiple pulse,Overbalanc

25、ed perforating, Stimulation.The Study about Deep Exploration Well C ementing T echnology in Q iaokou Oilf ieldF an Zhiyong(E ngineering Supervising C enter, Zhongyu an Oilf ield Company,SIN OPEC,H enan457001,P. R.Chinaand Ying Bin.F ault2B lock Oil&G as Field.2003, 10(5:8486Qiaokou oilfield is o

26、ne of the important areas where Zhongyuan Oilfield developed deep2layer natural gas these years.Oil and gas layers are deep and spread widely.The bottom temperature of the well is high,oil and gas intrude the lement loop easily.The strength of cement declines under the high temperature.According to

27、the above factors,anti2 intrude cement slurry system was researched and some pertinency measures are mentioned in the article.From 1999,10wells were applied.Once cementing qualified rate reaches to100%,and high2qualified rate reaches90%.The cementing technology is becoming more and more perfect.K ey Words:Qiaokou oilfield