同位素吸水剖面测井影响因素探讨

1、同位素吸水剖面测井影响因素探讨段艳丽姜萍蒋全涛刘传政(中原石油勘探局测井公司摘要同位素吸水剖面测井受诸多因素的影响,各种影响因素都会对资料的解释精度产生一定的影响。根据大量的测井资料对同位素污染、地层污染、同位素颗粒密度、粒径、同位素释放深度及时间、测井时间、施工方式、管柱腐蚀变形等进行了探讨分析,并对各种影响因素的识别与校正提出了相应的方法和依据。关键词注水井吸水剖面同位素污染影响因素随着油田注水开发时间的推移,由于污水回注、工程施工等措施的实施,都会导致储层性质发生变化,层间矛盾加剧,井况恶化,再加上同位素131Ba 载体本身所具有的物理特性,使同位素吸水剖面测井受到诸多因素的影响。因此,

2、在进行同位素吸水剖面测井时必须合理选择同位素载体,采取正确的施工方法,排除干扰因素才能测取优质资料。1同位素污染影响因素分析同位素污染原因,主要有:管柱的清洁、腐蚀程度;地层污染;同位素微球类型选择不当;同位素用量过大。此外,还有一些因固井质量引起的水泥环破坏、地层出砂,或是压裂酸化、地层屏蔽介质发生变化,都可能引起同位素污染。其中使用同位素不当造成的污染,经过选择可得到控制。污染类型分为吸附污染、沉淀污染,在资料解释中应根据污染类型及水流方向,采用污染校正归位法将污染分配给各吸水层,以消除同位素污染所造成的吸水偏差。2同位素载体的影响211同位素131Ba 微球粒径对于岩石颗粒粗细不均、孔喉

3、半径差异悬殊的储层,长期注水冲刷的结果,容易使高渗透层形成大孔道、微裂缝。若选择同位素微球粒径小于注水层的孔隙直径,同位素微球不像理想的那样滤积在吸水层的表面,而会进入冲刷带,超出仪器的探测范围,使测量幅度受到影响。在粒径满足了地层孔隙直径之后,所选择的同位素微球粒径也不宜过大,因为颗粒直径越大,注入水对其携带能力越差,颗粒的沉降速度越快,对注水管柱及井下工具污染的几率就越大。因此,所选择的同位素微球粒径必须满足以下方面1:131Ba 微球粒径必须大于注水层的孔隙直径;选择同位素微球粒径应与注水层段的渗透性和吸水层的有效厚度相适应;对于胶结疏松容易出砂、井筒周围出现冲刷带的地层或注水压力低、吸

4、水指数很高、单层突进严重的注水层,应选用大粒径同位素示踪剂,如600900m ,9001200m ;非均质性严重的地层,应选择同位素微球粒径跨度大一些,如100500m ,300900m ;偏心配水管柱的注水井,同位素颗粒直径要比出水口小23倍,以避免微球颗粒过大堵塞水嘴,造成井下工具的粘污。212同位素微球颗粒密度注入水分盐水、淡水、污水回注。注入水的密度不同,就要求有与其相匹配的同位素微球密度,若同位素的颗粒密度大于注入水的密度,同位素就会下沉造成井底堆积,或相同吸水强度的吸水482004年9月断块油气田FAU LT 2BLOCK OI L &G AS FIE LD第11卷第5期收

5、稿日期2004-04-18第一作者简介段艳丽,女,1963年生,高级测井技师,1985年毕业于中原石油学校,一直从事生产测井资料的验收解释工作,地址(457001:河南省濮阳市,电话:(03934823574。层底部有同位素异常显示,浅部同位素异常较低或没有异常显示。若同位素的密度小于注入水的密度,将造成同位素微球颗粒悬浮。因此,在进行吸水剖面测井时,无论出现哪种情况,都会造成相同吸水强度的吸水层吸水显示不均衡。例如W51-xx 井测井时注水量150m 3/d ,注水层位沙二下,注水方式为光管正注。第一次测量使用同位素粒径600900m ,颗粒密度1104g/cm 3。综合资料分析:11,12

6、号层应为该注水层段的主力吸水层,造成井温与同位素吸水显示对应性差的原因是同位素(颗粒密度大下沉,上返不到位(见图1同位素1所示 。图1W51-xx 井不同颗粒密度同位素对比测量213同位素微球颗粒密度的选择同位素颗粒密度应根据注入水的密度进行选择,而注入水的井下密度是水的矿化度、温度和压力的函数,使用Schlumberger 提供的经验公式确定井下注入水的密度2。w =w1/(6214w2w3w1=10.(3105×10-7S wic +11795w2=1(31444×10-6t 2+818798×10-5t +0100049w3=1(3148×10-4

7、P +2152×10-5t +01004252式中,w 为注入水的井下密度值,g/cm 3;w1、w2分别为注入水经矿化度、温度校正后的井下密度值,g/cm 3;w3为注入水经温度、压力校正后的井下密度值,g/cm 3;S wic 为注入水总矿化度,mg/L ;t 为注入水井下温度,;P 为注入水的井下流压,MPa 。根据经验公式计算注入水的井下密度,一个半衰期后,选用1102g/cm 3的同位素微球密度,在相同的注水施工条件下,再次对该井进行测量(见图1同位素2所示,同位素吸水显示正常。3测井施工方式的影响311同位素释放深度及时间同位素释放深度及时间必须依据注水量、注水压力的大小

8、而定。在注水量和注水压力较小的情况下,释放深度应控制在射孔层以上100m 左右,否则同位素就会在目的层上部形成人为的管柱粘污。反之,释放深度则应在射孔层以上150m 左右,若释放深度过浅,同位素来不及在注入水中均匀分布就会在井底形成堆积。同位素释放时间应在测完关井资料(静温、伽马基线后,仪器停在目的层之上,待注水压力平衡时,再打开释放器。因此合理掌握同位素释放深度及时间是保证同位素载体均匀分布于注入水之中,使同位素得到合理分配的关键。312同位素分配时间如果管壁脏,同位素污染严重,若等待同位素分配时间短,就容易使污染与吸水显示分不清或主次颠倒,在划分吸水面积时出现较大偏差,为此应延长同位素分配

9、时间,最大限度降低污染,使同位素在吸水层上有明显的异常显示为止(见图2中23102320m 井段和10,11号层处。在对吸水强度大的注水井段进行测井时,同位素到达目的层后应及时跟踪测量重复曲线,若等待时间长,同位素载体将随注入水进入地层深处,超出仪器的探测范围(见图2中的2,3,5号层所示,之后用流量计证实该处为大孔道地层。对于非均质性强,又存在大孔道的注水井进行测量时,应从同位素到达目的层后,连续跟踪测量多条同位素曲线,以便得到各类吸水层不同时间的吸水状况(见图2。58第11卷第5期段艳丽等1同位素吸水剖面测井影响因素探讨2004年9月图2P2-xx井非均质剖面连续测量4注水井井况的影响41

10、1伽马本底高当含有放射性杂质的物质随注入水进入射孔层后,将滤积在孔隙喉道附近,造成地层污染,孔隙堵塞,所测伽马曲线出现异常高值的反常现象。注入(释放同位素后,会出现整个测量井段污染严重,影响吸水层的吸水效果。因此,在对高伽马本底的注水井进行吸水剖面测井时:第一,把油管起至目的层上部20m左右,用标准接箍校深;第二,采用流量计测剖;第三,通知甲方解堵以恢复各层的吸水能力。412管柱腐蚀、井况恶化注水井由于长期注水或施工作业,容易造成管柱腐蚀或管壁结垢,在测井过程中仪器受到机械碰撞,稳定性变差,造成曲线变形失真。413管柱结构不合理采用偏心配水的注水井,若封隔器失效或卡在层上,主力吸水层得不到控制

11、,需要加强的吸水层得不到改善,增加了无效注水,导致对应油井含水率继续上升。5结论(1同位素污染对资料解释精度影响较大。若选用的同位素类型符合注入水质、注水剖面的岩性孔隙,同位素污染将得到有效控制。若是井况原因造成的同位素粘污,解释中应采用污染校正归位法进行定量计算。(2同位素释放深度由注水量及注水压力的大小而定。释放时间应在注水压力平衡时打开同位素释放器。(3同位素分配时间的长短应依据注水井的污染程度、吸水层的岩性特征而定。(4伽马本底高影响曲线的校深及吸水层的吸水效果,用标准接箍校深并加流量计测剖将避免污染影响。参考文献1姜文达1放射性同位素示踪注水剖面测井1北京:石油工业出版社,19972

12、王春利,张予生,缪定云等1返注井段同位素示踪注水剖面的分析研究1测井技术,2002,26(6:510513(编辑赵卫红2004年9月断块油气田第11卷第5期 R esearch of the T echnology of the W ater2injection and W ashing2w ell of the Sm all Oilfield F ar Aw ayZh ang Xiuqiong(Scientific R search I nstitute of Exploration and Development,Zhongyu an Oilfield Comp any,SIN OPEC,

13、Puyang457001,China,Lu G uihu a and Yang Xifei et al.F ault2B lock Oil&G as Field,2004,11 (5:75276This artical discusses the geographical character of the small oil2field far away.In order to save the project investment and running cost,and sim plify the technology of water2injection and washing2

14、well,the paper researches the new technology of the m oving water2injection and washing2well.I t can supply satis fying water2quality and quantity,at the same time it ensures to wash the wells far away.I t provides the g ood conditions to develop the small oilfield far away efficiently.K ey Words:Sm

15、all oilfield far away,Airtight water2supply and injection,M oving2washing well.C asing Drilling T echnologySong Jinchu(Drilling Comp any,Jiangh an Oilfield, SIN OPEC,Q ianjiang433121,China,Sun K unzhong and C ai Q ing et al.F ault2B lock Oil&G as Field,2004,11(5:772 79As a new technique,casing d

16、rilling changed conventional drilling technology.I t has a significant effect on present drilling. The paper introduces the advantages of casing drilling and casing drilling system,describes mainly the field test of casing drilling in the sur face,intermediate and production hole sections.C om pared

17、 with the wells drilled conventionally,casing drilling is m ore efficient,reducing downhole problems and saving drilling time and cost.K ey Words:Casing drilling,System,Drilling rigs,Field test,Drilling cost.The On2site Application of Boosting W ater I njection T echnique in Low Permeability R eserv

18、oirJia Yunfei(Oil&G as Administration Dep artment, Shengli Petroleum Administration Bureau,SIN OPEC, Dongying257002,China,Feng Yongli and You Longtan.F ault2B lock Oil&G as Field,2004,11(5:80281The main characters of low permeability reserv oir are of low porosity,fine pore throat,large filt

19、rational resistance,and fairly low productivity and water abs orbing capacity.M ost of injection wells possess high start2up prseeure which means bigger injecting pressure,and often the rate of water injection cannot satis fy injection allocation with bad injection result.In fluenced by the areal he

20、terogeneity,the operation cost of upgrading water injection sytstem wholly is always higher and low efficiency.Through the way of m ounting booster pum p on individual well,it will be achieved to increase water injection rate,prom ote the production am ong these affected wells,and finally im prove t

21、he s weep efficiency and oil recovery rate.K ey Words:Low permeable reserv oir,Water injection with pressure boosting,Booster pum p,E ffectiveness analyzing.Cementing T echnology of the First Du al B ranch H orizontal Well in T ahe OilfieldSh ao Jianzhong(E ngineering Supervision Center, Zhongyu an

22、Oilfield Comp any,Puyang457001,China, Ch ang Yonghui and Zh ang Shech ao et al.,F ault2B lock Oil &G as Field,2004,11(5:82283TK908DH is the first dual branch horizontal well in T ahe Oilfield.I t is the deepest in vertical depth in China.Main hole adopted tw o stage cementing technology,ensuring

23、 the cement job quality and providing the condition of success ful construction for branch horizontal section.The cement job quality is achieved to standard,bearing leakproofness in first and second branch hole cross is ensured,by adopting pegged liner hanger in branch horizontal section and cementi

24、ng technology on the top of screen pipe.Well com pletion technology is achieved to4grade of T AM L classification.The cementing technology offers valuable experience for deep branch horizontal well cement job.K ey Words:H ole structure,Main hole,Branch hole, Cementing technology,T ahe Oilfield.Discu

25、ssion of the F actors to A ffect the Profile of Isotope SuctionDu an Yanli(Logging Comp any,ZPEB,SIN OPEC, Puyang457001,China,Jiang Ping and Jiang Q u antao et al.F ault2B lock Oil&G as Field,2004,11(5:84286The profile of is otope suction was affected by a lot of factors.These factors w ould hav

26、e a certain im pact on the precision of data interpretation.These factors were investigated and analyzed,such as is otope pollution,formation contaminant, the density of is otope carrier,the diameter of is otope carrier,the depth and the time of is otope released,the logging time,the construction me

27、thod,tube corrosion etc.,from a large am ount of logging data.And the corresponding method and the evidence were advanced for identification and correction about various of in fluencing factors.K ey Words:Injection well,Water injection profile,Is otope pollution,In fluencing factors.Study of Logging I nterpret Method for Deep G as Zone in Dongpu DepressionT ang Yongmei(Logging Co