同位素吸水剖面測井影響因素探討

1、同位素吸水剖面測井影響因素探討段艷麗姜萍蔣全濤劉傳政(中原石油勘探局測井公司摘要同位素吸水剖面測井受諸多因素的影響,各種影響因素都會對資料的解釋精度產(chǎn)生一定的影響。根據(jù)大量的測井資料對同位素污染、地層污染、同位素顆粒密度、粒徑、同位素釋放深度及時間、測井時間、施工方式、管柱腐蝕變形等進行了探討分析,并對各種影響因素的識別與校正提出了相應的方法和依據(jù)。關鍵詞注水井吸水剖面同位素污染影響因素隨著油田注水開發(fā)時間的推移,由于污水回注、工程施工等措施的實施,都會導致儲層性質(zhì)發(fā)生變化,層間矛盾加劇,井況惡化,再加上同位素131Ba 載體本身所具有的物理特性,使同位素吸水剖面測井受到諸多因素的影響。因此,

2、在進行同位素吸水剖面測井時必須合理選擇同位素載體,采取正確的施工方法,排除干擾因素才能測取優(yōu)質(zhì)資料。1同位素污染影響因素分析同位素污染原因,主要有:管柱的清潔、腐蝕程度;地層污染;同位素微球類型選擇不當;同位素用量過大。此外,還有一些因固井質(zhì)量引起的水泥環(huán)破壞、地層出砂,或是壓裂酸化、地層屏蔽介質(zhì)發(fā)生變化,都可能引起同位素污染。其中使用同位素不當造成的污染,經(jīng)過選擇可得到控制。污染類型分為吸附污染、沉淀污染,在資料解釋中應根據(jù)污染類型及水流方向,采用污染校正歸位法將污染分配給各吸水層,以消除同位素污染所造成的吸水偏差。2同位素載體的影響211同位素131Ba 微球粒徑對于巖石顆粒粗細不均、孔喉

3、半徑差異懸殊的儲層,長期注水沖刷的結果,容易使高滲透層形成大孔道、微裂縫。若選擇同位素微球粒徑小于注水層的孔隙直徑,同位素微球不像理想的那樣濾積在吸水層的表面,而會進入沖刷帶,超出儀器的探測范圍,使測量幅度受到影響。在粒徑滿足了地層孔隙直徑之后,所選擇的同位素微球粒徑也不宜過大,因為顆粒直徑越大,注入水對其攜帶能力越差,顆粒的沉降速度越快,對注水管柱及井下工具污染的幾率就越大。因此,所選擇的同位素微球粒徑必須滿足以下方面1:131Ba 微球粒徑必須大于注水層的孔隙直徑;選擇同位素微球粒徑應與注水層段的滲透性和吸水層的有效厚度相適應;對于膠結疏松容易出砂、井筒周圍出現(xiàn)沖刷帶的地層或注水壓力低、吸

4、水指數(shù)很高、單層突進嚴重的注水層,應選用大粒徑同位素示蹤劑,如600900m ,9001200m ;非均質(zhì)性嚴重的地層,應選擇同位素微球粒徑跨度大一些,如100500m ,300900m ;偏心配水管柱的注水井,同位素顆粒直徑要比出水口小23倍,以避免微球顆粒過大堵塞水嘴,造成井下工具的粘污。212同位素微球顆粒密度注入水分鹽水、淡水、污水回注。注入水的密度不同,就要求有與其相匹配的同位素微球密度,若同位素的顆粒密度大于注入水的密度,同位素就會下沉造成井底堆積,或相同吸水強度的吸水482004年9月斷塊油氣田FAU LT 2BLOCK OI L &G AS FIE LD第11卷第5期收

5、稿日期2004-04-18第一作者簡介段艷麗,女,1963年生,高級測井技師,1985年畢業(yè)于中原石油學校,一直從事生產(chǎn)測井資料的驗收解釋工作,地址(457001:河南省濮陽市,電話:(03934823574。層底部有同位素異常顯示,淺部同位素異常較低或沒有異常顯示。若同位素的密度小于注入水的密度,將造成同位素微球顆粒懸浮。因此,在進行吸水剖面測井時,無論出現(xiàn)哪種情況,都會造成相同吸水強度的吸水層吸水顯示不均衡。例如W51-xx 井測井時注水量150m 3/d ,注水層位沙二下,注水方式為光管正注。第一次測量使用同位素粒徑600900m ,顆粒密度1104g/cm 3。綜合資料分析:11,12

6、號層應為該注水層段的主力吸水層,造成井溫與同位素吸水顯示對應性差的原因是同位素(顆粒密度大下沉,上返不到位(見圖1同位素1所示 。圖1W51-xx 井不同顆粒密度同位素對比測量213同位素微球顆粒密度的選擇同位素顆粒密度應根據(jù)注入水的密度進行選擇,而注入水的井下密度是水的礦化度、溫度和壓力的函數(shù),使用Schlumberger 提供的經(jīng)驗公式確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 為注入水的井下密度值,g/cm 3;w1、w2分別為注入水經(jīng)礦化度、溫度校正后的井下密度值,g/cm 3;w3為注入水經(jīng)溫度、壓力校正后的井下密度值,g/cm 3;S wic 為注入水總礦化度,mg/L ;t 為注入水井下溫度,;P 為注入水的井下流壓,MPa 。根據(jù)經(jīng)驗公式計算注入水的井下密度,一個半衰期后,選用1102g/cm 3的同位素微球密度,在相同的注水施工條件下,再次對該井進行測量(見圖1同位素2所示,同位素吸水顯示正常。3測井施工方式的影響311同位素釋放深度及時間同位素釋放深度及時間必須依據(jù)注水量、注水壓力的大小

8、而定。在注水量和注水壓力較小的情況下,釋放深度應控制在射孔層以上100m 左右,否則同位素就會在目的層上部形成人為的管柱粘污。反之,釋放深度則應在射孔層以上150m 左右,若釋放深度過淺,同位素來不及在注入水中均勻分布就會在井底形成堆積。同位素釋放時間應在測完關井資料(靜溫、伽馬基線后,儀器停在目的層之上,待注水壓力平衡時,再打開釋放器。因此合理掌握同位素釋放深度及時間是保證同位素載體均勻分布于注入水之中,使同位素得到合理分配的關鍵。312同位素分配時間如果管壁臟,同位素污染嚴重,若等待同位素分配時間短,就容易使污染與吸水顯示分不清或主次顛倒,在劃分吸水面積時出現(xiàn)較大偏差,為此應延長同位素分配

9、時間,最大限度降低污染,使同位素在吸水層上有明顯的異常顯示為止(見圖2中23102320m 井段和10,11號層處。在對吸水強度大的注水井段進行測井時,同位素到達目的層后應及時跟蹤測量重復曲線,若等待時間長,同位素載體將隨注入水進入地層深處,超出儀器的探測范圍(見圖2中的2,3,5號層所示,之后用流量計證實該處為大孔道地層。對于非均質(zhì)性強,又存在大孔道的注水井進行測量時,應從同位素到達目的層后,連續(xù)跟蹤測量多條同位素曲線,以便得到各類吸水層不同時間的吸水狀況(見圖2。58第11卷第5期段艷麗等1同位素吸水剖面測井影響因素探討2004年9月圖2P2-xx井非均質(zhì)剖面連續(xù)測量4注水井井況的影響41

10、1伽馬本底高當含有放射性雜質(zhì)的物質(zhì)隨注入水進入射孔層后,將濾積在孔隙喉道附近,造成地層污染,孔隙堵塞,所測伽馬曲線出現(xiàn)異常高值的反常現(xiàn)象。注入(釋放同位素后,會出現(xiàn)整個測量井段污染嚴重,影響吸水層的吸水效果。因此,在對高伽馬本底的注水井進行吸水剖面測井時:第一,把油管起至目的層上部20m左右,用標準接箍校深;第二,采用流量計測剖;第三,通知甲方解堵以恢復各層的吸水能力。412管柱腐蝕、井況惡化注水井由于長期注水或施工作業(yè),容易造成管柱腐蝕或管壁結垢,在測井過程中儀器受到機械碰撞,穩(wěn)定性變差,造成曲線變形失真。413管柱結構不合理采用偏心配水的注水井,若封隔器失效或卡在層上,主力吸水層得不到控制

11、,需要加強的吸水層得不到改善,增加了無效注水,導致對應油井含水率繼續(xù)上升。5結論(1同位素污染對資料解釋精度影響較大。若選用的同位素類型符合注入水質(zhì)、注水剖面的巖性孔隙,同位素污染將得到有效控制。若是井況原因造成的同位素粘污,解釋中應采用污染校正歸位法進行定量計算。(2同位素釋放深度由注水量及注水壓力的大小而定。釋放時間應在注水壓力平衡時打開同位素釋放器。(3同位素分配時間的長短應依據(jù)注水井的污染程度、吸水層的巖性特征而定。(4伽馬本底高影響曲線的校深及吸水層的吸水效果,用標準接箍校深并加流量計測剖將避免污染影響。參考文獻1姜文達1放射性同位素示蹤注水剖面測井1北京:石油工業(yè)出版社,19972

12、王春利,張予生,繆定云等1返注井段同位素示蹤注水剖面的分析研究1測井技術,2002,26(6:510513(編輯趙衛(wèi)紅2004年9月斷塊油氣田第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