碳(tan)(tan)鋼是(shi)油(you)(you)氣田(tian)采(cai)(cai)輸(shu)過(guo)(guo)(guo)程(cheng)(cheng)中(zhong)(zhong)(zhong)使(shi)用(yong)最廣的(de)(de)(de)(de)(de)(de)管材(cai)。在(zai)(zai)(zai)含CO2的(de)(de)(de)(de)(de)(de)環(huan)(huan)(huan)境中(zhong)(zhong)(zhong)，碳(tan)(tan)鋼非常容(rong)易發(fa)生(sheng)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)。目前，CO2腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)已(yi)經成(cheng)(cheng)為(wei)石油(you)(you)天(tian)然(ran)氣工(gong)業(ye)中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)一(yi)種重要(yao)(yao)的(de)(de)(de)(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)形式(shi)，導(dao)(dao)致(zhi)(zhi)了(le)管線(xian)(xian)和設備腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)失效(xiao)事(shi)故(gu)的(de)(de)(de)(de)(de)(de)頻發(fa)，從(cong)而(er)(er)(er)造成(cheng)(cheng)巨大(da)(da)的(de)(de)(de)(de)(de)(de)經濟損失、人(ren)員傷亡和環(huan)(huan)(huan)境破(po)壞。干(gan)燥的(de)(de)(de)(de)(de)(de)CO2對(dui)(dui)鋼鐵(tie)沒有(you)(you)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)作(zuo)(zuo)用(yong)，但(dan)當CO2溶于(yu)(yu)水(shui)(shui)(shui)后，在(zai)(zai)(zai)相(xiang)同(tong)(tong)的(de)(de)(de)(de)(de)(de)濃度(du)(du)(du)(du)(du)(du)下(xia)其(qi)(qi)總(zong)酸(suan)(suan)度(du)(du)(du)(du)(du)(du)高(gao)(gao)(gao)(gao)于(yu)(yu)鹽酸(suan)(suan)[1],因(yin)此(ci)其(qi)(qi)對(dui)(dui)鋼鐵(tie)的(de)(de)(de)(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)性(xing)極強。國內(nei)外(wai)學(xue)(xue)者普遍認可的(de)(de)(de)(de)(de)(de)均勻(yun)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)機理認為(wei)鋼鐵(tie)的(de)(de)(de)(de)(de)(de)CO2腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)過(guo)(guo)(guo)程(cheng)(cheng)可分(fen)為(wei)化(hua)(hua)學(xue)(xue)反(fan)(fan)(fan)應(ying)(ying)和電(dian)(dian)化(hua)(hua)學(xue)(xue)反(fan)(fan)(fan)應(ying)(ying)[2]：化(hua)(hua)學(xue)(xue)反(fan)(fan)(fan)應(ying)(ying)過(guo)(guo)(guo)程(cheng)(cheng)相(xiang)對(dui)(dui)簡單，包括 CO2溶于(yu)(yu)水(shui)(shui)(shui)形成(cheng)(cheng)H2CO3的(de)(de)(de)(de)(de)(de)過(guo)(guo)(guo)程(cheng)(cheng)、H2CO3一(yi)級和二級電(dian)(dian)離(li)過(guo)(guo)(guo)程(cheng)(cheng)以(yi)及(ji)碳(tan)(tan)鋼溶解形成(cheng)(cheng)活化(hua)(hua)粒(li)子(zi)和碳(tan)(tan)酸(suan)(suan)鹽生(sheng)成(cheng)(cheng)的(de)(de)(de)(de)(de)(de)過(guo)(guo)(guo)程(cheng)(cheng)；電(dian)(dian)化(hua)(hua)學(xue)(xue)反(fan)(fan)(fan)應(ying)(ying)過(guo)(guo)(guo)程(cheng)(cheng)包括陽(yang)極失去電(dian)(dian)子(zi)被(bei)氧化(hua)(hua)的(de)(de)(de)(de)(de)(de)過(guo)(guo)(guo)程(cheng)(cheng)、陰(yin)極得到電(dian)(dian)子(zi)被(bei)還原的(de)(de)(de)(de)(de)(de)過(guo)(guo)(guo)程(cheng)(cheng)和電(dian)(dian)子(zi)傳輸(shu)的(de)(de)(de)(de)(de)(de)過(guo)(guo)(guo)程(cheng)(cheng)，但(dan)由于(yu)(yu)CO2在(zai)(zai)(zai)水(shui)(shui)(shui)中(zhong)(zhong)(zhong)會(hui)發(fa)生(sheng)水(shui)(shui)(shui)合(he)反(fan)(fan)(fan)應(ying)(ying)和兩級電(dian)(dian)離(li)，因(yin)此(ci)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)中(zhong)(zhong)(zhong)間產物(wu)多種多樣(yang) （如FeOH[3],Fe（OH）2[4],Fe（HCO3）2[5]和Fe（HCO3）OH[6]），而(er)(er)(er)陰(yin)極反(fan)(fan)(fan)應(ying)(ying)過(guo)(guo)(guo)程(cheng)(cheng)也(ye)涉及(ji)到H+,H2O,H2CO3和HCO3-的(de)(de)(de)(de)(de)(de)還原。而(er)(er)(er)對(dui)(dui)于(yu)(yu)局部腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)，反(fan)(fan)(fan)應(ying)(ying)更為(wei)復雜，它的(de)(de)(de)(de)(de)(de)產生(sheng)和發(fa)展與鋼材(cai)的(de)(de)(de)(de)(de)(de)表面(mian)狀態、腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)產物(wu)膜(mo)的(de)(de)(de)(de)(de)(de)性(xing)質以(yi)及(ji)環(huan)(huan)(huan)境因(yin)素有(you)(you)關(guan)，反(fan)(fan)(fan)應(ying)(ying)過(guo)(guo)(guo)程(cheng)(cheng)也(ye)可能與均勻(yun)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)有(you)(you)所不(bu)(bu)同(tong)(tong)[7-9]。由于(yu)(yu)各油(you)(you)田(tian)所處的(de)(de)(de)(de)(de)(de)地理位置和環(huan)(huan)(huan)境不(bu)(bu)同(tong)(tong)，因(yin)此(ci)不(bu)(bu)同(tong)(tong)的(de)(de)(de)(de)(de)(de)油(you)(you)田(tian)采(cai)(cai)出(chu)水(shui)(shui)(shui)的(de)(de)(de)(de)(de)(de)特點(dian)(dian)也(ye)不(bu)(bu)盡相(xiang)同(tong)(tong)。但(dan)是(shi)不(bu)(bu)同(tong)(tong)的(de)(de)(de)(de)(de)(de)采(cai)(cai)出(chu)水(shui)(shui)(shui)之(zhi)間也(ye)存在(zai)(zai)(zai)著一(yi)些共同(tong)(tong)特性(xing)。總(zong)體上存在(zai)(zai)(zai)以(yi)下(xia)特點(dian)(dian)[10],水(shui)(shui)(shui)溫(wen)(wen)基本(ben)保持在(zai)(zai)(zai)20~90 ℃，溫(wen)(wen)度(du)(du)(du)(du)(du)(du)相(xiang)對(dui)(dui)比較高(gao)(gao)(gao)(gao)；油(you)(you)田(tian)采(cai)(cai)出(chu)水(shui)(shui)(shui)中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)礦化(hua)(hua)度(du)(du)(du)(du)(du)(du)非常高(gao)(gao)(gao)(gao)，高(gao)(gao)(gao)(gao)的(de)(de)(de)(de)(de)(de)礦化(hua)(hua)度(du)(du)(du)(du)(du)(du)容(rong)易導(dao)(dao)致(zhi)(zhi)管線(xian)(xian)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)破(po)裂，給(gei)工(gong)作(zuo)(zuo)處理帶來困(kun)難(nan)甚至發(fa)生(sheng)嚴重事(shi)故(gu)。影(ying)響管線(xian)(xian)鋼腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)因(yin)素有(you)(you)很(hen)多，其(qi)(qi)中(zhong)(zhong)(zhong)首要(yao)(yao)的(de)(de)(de)(de)(de)(de)因(yin)素是(shi)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)影(ying)響，溫(wen)(wen)度(du)(du)(du)(du)(du)(du)對(dui)(dui)管線(xian)(xian)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)有(you)(you)十分(fen)重要(yao)(yao)的(de)(de)(de)(de)(de)(de)影(ying)響，通常來說溫(wen)(wen)度(du)(du)(du)(du)(du)(du)主要(yao)(yao)是(shi)影(ying)響材(cai)料表面(mian)的(de)(de)(de)(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)產物(wu)膜(mo)，進而(er)(er)(er)影(ying)響腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速率(lv)(lv)[11]。眾所周知，溫(wen)(wen)度(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)升(sheng)(sheng)高(gao)(gao)(gao)(gao)，可以(yi)加(jia)快腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)化(hua)(hua)學(xue)(xue)反(fan)(fan)(fan)應(ying)(ying)、電(dian)(dian)化(hua)(hua)學(xue)(xue)反(fan)(fan)(fan)應(ying)(ying)以(yi)及(ji)傳質過(guo)(guo)(guo)程(cheng)(cheng)，從(cong)而(er)(er)(er)加(jia)速腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)發(fa)生(sheng)。但(dan)是(shi)也(ye)不(bu)(bu)是(shi)說腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速率(lv)(lv)會(hui)隨著溫(wen)(wen)度(du)(du)(du)(du)(du)(du)升(sheng)(sheng)高(gao)(gao)(gao)(gao)而(er)(er)(er)一(yi)味的(de)(de)(de)(de)(de)(de)升(sheng)(sheng)高(gao)(gao)(gao)(gao)，在(zai)(zai)(zai)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)升(sheng)(sheng)高(gao)(gao)(gao)(gao)過(guo)(guo)(guo)程(cheng)(cheng)中(zhong)(zhong)(zhong)存在(zai)(zai)(zai)很(hen)多轉折點(dian)(dian)。研(yan)究(jiu)人(ren)員對(dui)(dui)此(ci)進行了(le)大(da)(da)量的(de)(de)(de)(de)(de)(de)工(gong)作(zuo)(zuo)，Ikeda等[12]測試了(le)不(bu)(bu)同(tong)(tong)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)下(xia)碳(tan)(tan)鋼在(zai)(zai)(zai)溶液中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)極化(hua)(hua)曲線(xian)(xian)，結果(guo)表明，溫(wen)(wen)度(du)(du)(du)(du)(du)(du)升(sheng)(sheng)高(gao)(gao)(gao)(gao)使(shi)得陰(yin)、陽(yang)極電(dian)(dian)流密(mi)(mi)度(du)(du)(du)(du)(du)(du)增大(da)(da)。Zhang等[13]對(dui)(dui)飽和CO2環(huan)(huan)(huan)境中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速率(lv)(lv)進行了(le)研(yan)究(jiu)發(fa)現腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)速率(lv)(lv)與溫(wen)(wen)度(du)(du)(du)(du)(du)(du)有(you)(you)很(hen)密(mi)(mi)切的(de)(de)(de)(de)(de)(de)關(guan)系。本(ben)文通過(guo)(guo)(guo)在(zai)(zai)(zai)不(bu)(bu)同(tong)(tong)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)下(xia)進行浸泡實驗和電(dian)(dian)化(hua)(hua)學(xue)(xue)實驗研(yan)究(jiu)了(le)L245鋼在(zai)(zai)(zai)模擬油(you)(you)氣田(tian)采(cai)(cai)出(chu)水(shui)(shui)(shui)環(huan)(huan)(huan)境中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)腐(fu)(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)(shi)行為(wei)，并為(wei)L245鋼在(zai)(zai)(zai)油(you)(you)氣田(tian)采(cai)(cai)出(chu)水(shui)(shui)(shui)中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)合(he)理應(ying)(ying)用(yong)提供參考依據。

1 實驗方法

1.1 實驗(yan)材料的制備

實驗材(cai)料采用L245鋼(gang)，其(qi)化學成分 （質量分數(shu)，%） 為(wei)：C 0.135,Si 0.350,Mn 1.350,S 0.007,P 0.015,Fe余量。

浸泡實(shi)驗(yan)采用(yong)試(shi)片規格為45 mm×10 mm×3 mm （含Φ5 mm的(de)孔），試(shi)樣表面(mian)依次(ci)用(yong)SiC砂(sha)紙(zhi)逐(zhu)級打磨至1000#,打磨后(hou)的(de)試(shi)樣依次(ci)在去離子水、丙酮和(he)無(wu)水乙醇中超聲輔助清(qing)洗5 min,吹干(gan)(gan)備(bei)用(yong)。電(dian)化學測試(shi)試(shi)樣為直徑15 mm、厚(hou)3 mm的(de)圓柱形電(dian)極，試(shi)樣背面(mian)用(yong)錫(xi)焊(han)連(lian)接(jie)Cu導線，用(yong)環(huan)氧(yang)樹(shu)脂封(feng)樣后(hou)，依次(ci)用(yong)金相砂(sha)紙(zhi)逐(zhu)級打磨至1000#,然后(hou)用(yong)去離子水沖洗，用(yong)丙酮清(qing)洗除油，用(yong)無(wu)水乙醇清(qing)洗后(hou)，吹干(gan)(gan)備(bei)用(yong)。實(shi)驗(yan)介質(zhi)為164.79 g/L的(de)NaCl溶(rong)液。實(shi)驗(yan)前向(xiang)溶(rong)液中通(tong)(tong)高純(chun)氬(ya)氣90 min除氧(yang)，然后(hou)向(xiang)溶(rong)液中通(tong)(tong)入CO2大約60 min后(hou)放入試(shi)樣，整個(ge)實(shi)驗(yan)中持(chi)續通(tong)(tong)入CO2以(yi)保(bao)(bao)證CO2始終(zhong)保(bao)(bao)持(chi)飽和(he)狀(zhuang)(zhuang)態(tai)，以(yi)模(mo)擬(ni)Cl-含量較高以(yi)及CO2飽和(he)狀(zhuang)(zhuang)況下(xia)的(de)油氣田模(mo)擬(ni)水。實(shi)驗(yan)中用(yong)水浴(yu)鍋對模(mo)擬(ni)溶(rong)液進行(xing)恒(heng)溫加熱并保(bao)(bao)溫。溫度分別(bie)設(she)定(ding)為30,60和(he)90 ℃。

1.2 浸泡實驗失重處理

將浸泡(pao)240 h后(hou)(hou)的試(shi)樣從(cong)模擬(ni)溶液(ye)(ye)中(zhong)(zhong)取出后(hou)(hou)用(yong)水沖(chong)洗(xi)(xi)(xi)(xi)，放入酸(suan)(suan)清洗(xi)(xi)(xi)(xi)液(ye)(ye)中(zhong)(zhong)超(chao)聲輔助(zhu)清洗(xi)(xi)(xi)(xi)5 min。酸(suan)(suan)清洗(xi)(xi)(xi)(xi)液(ye)(ye)的基本(ben)要求(qiu)為：（1） 應能(neng)全部除(chu)去試(shi)片(pian)上(shang)的腐蝕產(chan)物沉積物；（2） 原則上(shang)是既能(neng)迅速、順利地去除(chu)試(shi)片(pian)上(shang)的沉積物，又能(neng)基本(ben)上(shang)不侵蝕金(jin)屬(shu)本(ben)體。酸(suan)(suan)清洗(xi)(xi)(xi)(xi)液(ye)(ye)的配比：鹽(yan)酸(suan)(suan)100 mL,六次甲基四(si)胺10 g,加水至1 L,取出后(hou)(hou)用(yong)無水乙醇超(chao)聲脫(tuo)水，吹干(gan)后(hou)(hou)放入干(gan)燥器中(zhong)(zhong)，8 h后(hou)(hou)用(yong)Sartorius TE124S天平 （精度0.1 mg） 進行稱(cheng)重，每個(ge)條件下對(dui)3個(ge)平行樣分別稱(cheng)重，結果取平均值。

1.3 電化學測量

采(cai)用三電(dian)(dian)(dian)極體(ti)系，在PGSTAT100N型電(dian)(dian)(dian)化(hua)學(xue)工作站(zhan)上進行電(dian)(dian)(dian)化(hua)學(xue)實驗(yan)(yan)。工作電(dian)(dian)(dian)極為(wei)(wei)L245鋼試樣，參(can)比(bi)電(dian)(dian)(dian)極為(wei)(wei)飽(bao)(bao)和甘汞電(dian)(dian)(dian)極 （SCE），輔助電(dian)(dian)(dian)極為(wei)(wei)Pt片，溶(rong)液(ye)體(ti)積為(wei)(wei)1000 mL。實驗(yan)(yan)溶(rong)液(ye)用CO2除氧2 h至飽(bao)(bao)和。實驗(yan)(yan)溫度分(fen)別為(wei)(wei)30,60和90 ℃，壓力為(wei)(wei)常壓。動電(dian)(dian)(dian)位極化(hua)曲(qu)線的(de)掃(sao)描(miao)速率(lv)為(wei)(wei)0.33 mV/s,掃(sao)描(miao)電(dian)(dian)(dian)位范(fan)圍為(wei)(wei)±250 mV （相對于開路電(dian)(dian)(dian)位），并對曲(qu)線進行擬合。電(dian)(dian)(dian)化(hua)學(xue)阻(zu)抗譜的(de)測試頻(pin)率(lv)為(wei)(wei)105~5×10-3 Hz,交流激勵信號為(wei)(wei)幅值為(wei)(wei)±5 mV的(de)正弦波。

1.4 腐(fu)蝕形貌(mao)分析

采(cai)用(yong)FEI-2000型掃描電(dian)子顯微鏡 （SEM） 對浸泡實驗(yan)后(hou)的試樣進行(xing)腐蝕形貌(mao)觀察。

2 結果與討論(lun)

2.1 失重實驗

圖1為L245鋼在不同溫度(du)的油氣田模擬(ni)水中浸泡(pao)10 d后的腐(fu)蝕速(su)率(lv)。可以看出(chu)，隨著溫度(du)的升高(gao)，L245鋼的腐(fu)蝕速(su)率(lv)逐漸加(jia)快，說明溫度(du)升高(gao)加(jia)快了(le)腐(fu)蝕。

圖1 L245鋼(gang)在不同溫度油(you)氣(qi)田模擬采(cai)出水(shui)中浸泡10 d后的腐蝕速率

2.2 電化學(xue)測(ce)試

2.2.1 動(dong)電(dian)(dian)位(wei)極(ji)化曲(qu)(qu)線測試結果(guo) 圖2為L245鋼(gang)(gang)在不同溫(wen)(wen)度下(xia)(xia)的(de)動(dong)電(dian)(dian)位(wei)極(ji)化曲(qu)(qu)線，表(biao)1是各極(ji)化曲(qu)(qu)線的(de)電(dian)(dian)化學(xue)參數擬合結果(guo)。從圖2中可以看出，當(dang)溫(wen)(wen)度升高(gao)時，L245鋼(gang)(gang)的(de)自腐(fu)(fu)(fu)(fu)蝕電(dian)(dian)位(wei)正移(yi)，整體處于活化溶解狀(zhuang)態。從表(biao)2可以看出，隨著溫(wen)(wen)度升高(gao)L245鋼(gang)(gang)的(de)腐(fu)(fu)(fu)(fu)蝕電(dian)(dian)流(liu)逐步增大，腐(fu)(fu)(fu)(fu)蝕速率(lv)不斷加快。當(dang)溫(wen)(wen)度升高(gao)至90 ℃時自腐(fu)(fu)(fu)(fu)蝕電(dian)(dian)流(liu)升高(gao)到177 μAcm-2,遠遠大于其(qi)余兩個溫(wen)(wen)度條件(jian)下(xia)(xia)的(de)自腐(fu)(fu)(fu)(fu)蝕電(dian)(dian)流(liu)，說(shuo)(shuo)明(ming)L245鋼(gang)(gang)在高(gao)溫(wen)(wen)下(xia)(xia)反應比較劇烈(lie)。同時通過表(biao)2可以看出，隨著溫(wen)(wen)度的(de)升高(gao)ba的(de)變化不大，而bc的(de)變化較大，說(shuo)(shuo)明(ming)溫(wen)(wen)度升高(gao)對(dui)陽極(ji)反應影響(xiang)較小，而對(dui)陰(yin)(yin)極(ji)反應影響(xiang)較大，從而可知腐(fu)(fu)(fu)(fu)蝕反應過程主要由陰(yin)(yin)極(ji)控制。

2.2.2 電化學阻(zu)抗測量結果 圖(tu)3為L245鋼(gang)(gang)在不(bu)同(tong)溫(wen)(wen)度下的Nyquist圖(tu)和Bode圖(tu)。可以(yi)看出隨著(zhu)(zhu)溫(wen)(wen)度的升高(gao)(gao)(gao)，L245鋼(gang)(gang)的容抗弧不(bu)斷(duan)減(jian)小，從Bode圖(tu)中可以(yi)看出，溫(wen)(wen)度升高(gao)(gao)(gao)相位角峰向高(gao)(gao)(gao)頻移動，說明(ming)(ming)L245鋼(gang)(gang)的抗腐蝕(shi)性隨著(zhu)(zhu)溫(wen)(wen)度升高(gao)(gao)(gao)逐(zhu)漸減(jian)弱，說明(ming)(ming)溫(wen)(wen)度的升高(gao)(gao)(gao)減(jian)小了腐蝕(shi)反應(ying)的阻(zu)力(li)，導致腐蝕(shi)速率增(zeng)加(jia)，這(zhe)一(yi)結果與(yu)極化曲線的結果一(yi)致。

對(dui)以(yi)上電(dian)(dian)化(hua)學阻抗結(jie)(jie)果進(jin)行等效(xiao)電(dian)(dian)路擬(ni)合(he) （圖4），擬(ni)合(he)結(jie)(jie)果如(ru)表(biao)2所示。其中(zhong)，Rs為(wei)溶液電(dian)(dian)阻，Cd為(wei)電(dian)(dian)化(hua)學反應電(dian)(dian)容，Rt為(wei)電(dian)(dian)荷(he)轉移電(dian)(dian)阻，Q為(wei)腐蝕產物膜(mo)電(dian)(dian)容，Rf為(wei)電(dian)(dian)極表(biao)面腐蝕產物膜(mo)電(dian)(dian)阻。從(cong)表(biao)2可以(yi)看出，隨著溫度的升高，Rt減小，腐蝕速率增加。

圖(tu)2 L245鋼在(zai)不(bu)同溫度油氣田模擬水中的動電位極化曲線(xian)

圖3 L245鋼在(zai)不同溫度的(de)(de)油氣田模擬水中的(de)(de)Nyquist圖和(he)Bode圖

圖4 L245鋼(gang)在不同溫(wen)度的油氣田模擬水中電化學阻抗等效擬合電路

表1 L245鋼在不(bu)同溫度的油氣田采出水中極化曲線(xian)擬(ni)合結果(guo)

表(biao)2 L245鋼(gang)在模擬(ni)油田采出水(shui)中不同(tong)溫度下(xia)電(dian)化學阻抗(kang)擬(ni)合(he)所得電(dian)化學參數

2.3 腐蝕(shi)表面(mian)形貌結(jie)果

圖5是L245鋼在不同溫(wen)(wen)度下的油氣田模擬水中浸泡10 d后表面的SEM像。可(ke)以看出，在3個溫(wen)(wen)度條件下分別(bie)發生了均(jun)勻腐(fu)蝕(shi)(shi)和(he)局(ju)部(bu)腐(fu)蝕(shi)(shi)。30 ℃時(shi)均(jun)勻腐(fu)蝕(shi)(shi)的膜(mo)層產(chan)物較少(shao)，腐(fu)蝕(shi)(shi)類型為均(jun)勻腐(fu)蝕(shi)(shi)。當溫(wen)(wen)度升高(gao)到60 ℃時(shi)，腐(fu)蝕(shi)(shi)形貌發生顯著(zhu)變化，L245鋼表面發生局(ju)部(bu)腐(fu)蝕(shi)(shi)。溫(wen)(wen)度升高(gao)至(zhi)90 ℃時(shi)，腐(fu)蝕(shi)(shi)產(chan)物增多(duo)，局(ju)部(bu)腐(fu)蝕(shi)(shi)數量(liang)增加(jia)。

圖5 L245鋼在不同溫度的模擬油田采出水中浸泡10 d后的腐蝕形貌

2.4 分析與討(tao)論

在(zai)油氣田采出(chu)水的腐蝕過(guo)程中，腐蝕反應[14]如下：

溫(wen)(wen)度(du)主(zhu)(zhu)要是(shi)影(ying)響材(cai)料表面腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)產(chan)物(wu)膜的(de)化學(xue)組(zu)成和(he)厚度(du)[15],進而影(ying)響腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)速率(lv)。在飽和(he)CO2環境(jing)下，腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)反應(ying)(ying)主(zhu)(zhu)要由(you)陰極(ji)反應(ying)(ying)來控(kong)制整(zheng)個反應(ying)(ying)速度(du)[16],通(tong)過動電(dian)位(wei)極(ji)化曲線發現溫(wen)(wen)度(du)升高加(jia)快了陰極(ji)反應(ying)(ying)速度(du)，使整(zheng)個腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)反應(ying)(ying)越(yue)(yue)來越(yue)(yue)劇烈。在腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)開始階段，Fe不(bu)斷發生(sheng)(sheng)陽極(ji)溶解，反應(ying)(ying)表面附(fu)近(jin)Fe2+濃度(du)較(jiao)高，反應(ying)(ying)表面會生(sheng)(sheng)成一層疏松的(de)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)產(chan)物(wu)膜，在常溫(wen)(wen)下Cl-的(de)存在降低了CO2的(de)溶解度(du)[17]使碳鋼(gang)的(de)腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)速率(lv)降低，溫(wen)(wen)度(du)升高使腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)速率(lv)增加(jia)生(sheng)(sheng)成疏松的(de)FeCO3,隨(sui)著反應(ying)(ying)時(shi)間推移腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)產(chan)物(wu)膜逐漸累積(ji)，當局(ju)部腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)產(chan)物(wu)膜累積(ji)到一定程度(du)后產(chan)生(sheng)(sheng)內應(ying)(ying)力使腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)產(chan)物(wu)開裂(lie)，從而使半徑(jing)較(jiao)小的(de)Cl-通(tong)過裂(lie)縫(feng)進入內部發生(sheng)(sheng)局(ju)部腐(fu)(fu)(fu)蝕(shi)(shi)(shi)(shi)。

3 結(jie)論

（1） 溫(wen)(wen)度(du)對(dui)L245鋼的CO2腐蝕(shi)有(you)顯著影響，在低溫(wen)(wen)階段 （≤90 ℃），腐蝕(shi)速率隨(sui)著溫(wen)(wen)度(du)的升高(gao)而加(jia)快。

（2） 常溫下 （30 ℃） L245鋼的CO2腐蝕(shi)主(zhu)要為均勻腐蝕(shi)，當(dang)溫度升高(gao)至60 ℃開始(shi)發生局(ju)部(bu)腐蝕(shi)，局(ju)部(bu)腐蝕(shi)反應隨(sui)著溫度升高(gao)而加劇。