鉆桿管體中部失效的(de)(de)原因在(zai)(zai)于:鉆(zhan)桿由于在(zai)(zai)腐蝕介質下長時間存放而產生蝕坑,蝕坑周圍(wei)存在(zai)(zai)微(wei)裂(lie)(lie)紋在(zai)(zai)鉆(zhan)井過(guo)程中,因承受彎曲交變(bian)應(ying)力,即在(zai)(zai)蝕坑底部這個應(ying)力集中的(de)(de)地(di)方(fang)產生初始裂(lie)(lie)紋,隨(sui)著服役(yi)過(guo)程的(de)(de)推(tui)移,微(wei)裂(lie)(lie)紋會慢慢擴展。由于該(gai)部位的(de)(de)正常磨損和(he)偏(pian)磨,使(shi)壁厚變(bian)薄,則使(shi)裂(lie)(lie)紋擴展加快,并迅(xun)速(su)達到管體刺穿,甚至斷裂(lie)(lie),造成失效事故。

1)鉆桿修復管(guan)體失(shi)效(xiao)(xiao)事(shi)故大部分發(fa)生(sheng)(sheng)在內(nei)加厚(hou)過渡區消失(shi)部位(wei),占70%。失(shi)效(xiao)(xiao)原(yuan)因在于結構不合理(li),造成(cheng)應力集中(zhong),產生(sheng)(sheng)腐(fu)蝕(shi)疲勞(lao)。鉆桿管(guan)體中(zhong)部失(shi)效(xiao)(xiao)事(shi)故占30%。失(shi)效(xiao)(xiao)原(yuan)因是由于磨料磨損(sun)造成(cheng)壁厚(hou)變薄及蝕(shi)坑造成(cheng)的腐(fu)蝕(shi)共(gong)同作(zuo)用的結果。

2)建議加(jia)強焊(han)前管體檢(jian)驗,對(dui)所有待(dai)焊(han)鉆桿進(jin)(jin)行管體無損檢(jian)測(ce),對(dui)內腐蝕嚴(yan)重的進(jin)(jin)行報廢處理(li),確保管體質(zhi)量;對(dui)鉆桿加(jia)厚過(guo)(guo)渡(du)(du)區周圍進(jin)(jin)行超聲波(bo)探傷(shang),以檢(jian)查(cha)過(guo)(guo)渡(du)(du)區有無缺陷;鉆桿對(dui)焊(han)前應檢(jian)查(cha)內加(jia)厚過(guo)(guo)渡(du)(du)區長度及過(guo)(guo)渡(du)(du)區消失處的圓弧(hu)半徑,凡內加(jia)厚過(guo)(guo)渡(du)(du)區<100mm,R<300mm者不得焊(han)接。

3)加(jia)強(qiang)鉆井(jing)液管理,在(zai)(zai)條件許可的(de)情況下,鉆井(jing)液pH值應保持在(zai)(zai)10或10以(yi)上。泵壓(ya)下降時(shi),如能準確判斷(duan)應及時(shi)停鉆,可防止鉆桿斷(duan)裂造成重(zhong)大(da)失效事故。提高鉆井(jing)工(gong)藝水平,減少/狗腿0嚴重(zhong)度(du)(du)。優先選(xuan)用(yong)低強(qiang)度(du)(du)鉆桿。

鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)是(shi)(shi)指鑿洞、鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)孔等(deng)與之有關使用的工具(ju)(ju)。為(wei)專門目的而配(pei)備(bei)的裝備(bei)、儀器(qi)和(he)(he)機(ji)械(xie)。如深(shen)井(jing)鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)，石油鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)等(deng)。鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)塔及為(wei)鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)孔和(he)(he)日(ri)后抽油所必要的機(ji)房和(he)(he)其(qi)它的全(quan)套設備(bei)。鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)由(you)主(zhu)動(dong)鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)桿(gan)、鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)桿(gan)、巖心管以及底(di)端的擴孔器(qi)和(he)(he)鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)頭組(zu)成(cheng)，必要時(shi)還(huan)在(zai)巖心管上(shang)部(bu)加接(jie)沉淀管或鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)鋌。鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)的功用主(zhu)要是(shi)(shi)在(zai)鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)探(tan)巖層過(guo)程中(zhong)給鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)頭傳遞鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)頭壓力和(he)(he)回轉扭矩，并向孔底(di)輸送鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)孔沖洗液，收取巖礦心。鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)的各個(ge)組(zu)成(cheng)部(bu)分都(dou)是(shi)(shi)用優質無縫鋼管制成(cheng)，有優良的物理力學性能(neng)，以承受鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)探(tan)過(guo)程中(zhong)鉆(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)(zhan)具(ju)(ju)自身的交變(bian)載荷、疲勞和(he)(he)磨損(sun)。