金属储罐底板外侧阴极保护电位分布的解析计算法[1]_图文

1、 第3期 金属储罐底板外侧阴极保护电位分布的解析计算法 103 d (y = dy is r ( 2 + ky 2 2 (2 + k ( 16 d i (y = 2 i0 k y = dy 4k is y ( k + 2 ( 17 r 2 ( 18 + ky 8k y 1 可见, 罐底金属的极化电位也可认为和极化电流密度成正比, 但和管道情况不同 , 其比例系数是罐底位 置的函数。 离罐底中心越近, 极化曲线越陡 ( 极化电阻越大 。 式 ( 18 还反映出罐底金属极化行为和经验常数 k 两式相除得 及罐径、 土壤电阻率等参数存在某些联系。 413减少罐底保护电位分布不均匀性的讨论 d U a

2、 U m 。 21 罐底流动电流造成的设备电位变化为微伏级, 对罐底保护电位分布无实际影响。 31 当阳极离罐体距离较近时 ( 比如: 小于35m , 阳极电场对罐底保护电位分布会产生明显影响, 其特征是 罐底边缘上的保护电位不均匀, 最大可达到几百 mV 。 41 当阳极离罐较远, 罐底保护电位分布只决定于阴极电位, 理论推导及实验研究表明, 保护电位和距罐底 圆心距离呈立方抛物线关系。 此公式与实际数据吻合良好。 51 罐底保护电位不均匀性 ( 最大电位差 和罐底平均电流密度、 土壤电阻率及罐半径三项参数乘积成正 比。 从这些解析式可开展罐底保护电位分布的参数优化工作。 参 考 文 献 1

3、尤里克 H H 1等著1腐蚀与腐蚀控制1翁永基译1北京: 石油工业出版社, 1995: 516 5211 2 161. M o rgan J H Cathod ic. P ro tection. L eonard H illBook L i m ited, L ondon, 1959: 159 3邱枫, 徐乃欣. 钢质储罐底板外侧阴极保护时的电位分布1中国腐蚀与防护学报, 1996, 16 (1 : 29 351 4张鸣镝, 殷正安等1有限差分法计算海底管道阴极保护时的电位分布1中国腐蚀与防护学报, 1994, 14 (1 : 77 811 5贝克曼 W V 1著1阴极保护简明手册1赖敬文译1

4、北京: 石油工业出版社, 1987: 431 6金绩祖等编著1场论习题解答1北京: 地质出版社, 1985: 2071 7Garrity K C and U rbas M. Cathod ic p ro tection of ex ternal tank bo ttom s. M aterials Perfo rm ance, 1998, 27 (4 : 32 35. ( 本文收到日期1997209216编辑张君娥 第 3 期石油学报 . m o re, these m ethod s a i m ed a t comm on u ses have been confirm ed effect

5、ive in a num ber of o il field s 7 Key words log face p a rtia l com ponen t ana lysis op ti m iza tion dua l po ro sity w a ter m odel sa lin ity co re electric m ea su rem en t PETROL EUM ENG INEER ING A STU D Y ON TH E PRODU CT I V IT Y CAL CU LA T I ON O F W ELL S ACTA 1998, 19 ( 3 . (X ian P et

6、roleum Institu te L i D ang et a l T h is p ap er g ives the p roductivity of w ells by confo rm a l tran sfo rm a tion and equ iva len t filtera te resistance m ethod. Com p a ring it w ith and Jo sh is fo rm u la ind ica ted tha t they d idnt d istingu ish the a ssum p tion of un ifo rm flux from

7、the a ssum p tion of infin ite conductivity. T he influences of the b ranch num ber and the ho rizon ta l section leng th of m u ltib ranch w ells on p roductivity a re d iscu ssed. T he p roductivity of ho rizon ta lw ell w ith longer ho rizon ta l section is g rea ter than the p roductivity of m u

8、 ltip le devia2 . T he p roductivity fo rm u la tion w ells, if the leng th of a ll b ranches is the sam e w ith ho rizon ta l section leng th of a ho rizon ta l w ell . g iven here is theo retica lly co rrect, and can be u sed in the design and the p roductivity esti m a tion of m u ltib ranch w el

9、ls Key wordsb ranch ho rizon ta l w ellp roductivityconfo rm a l tran sfo rm a tion A STU D Y ON L EA K PO I N T LO CA T I N G O F CRU D E O I L P IPEL I N ES ACTA 1998, 19 ( 3 . (T ianj in U n iv ersity J in Sh ijiu et a l P ip eline tran spo rta tion p lays a m o re and m o re i m po rtan t p a rt

10、 in w o rlds econom y. B u t p ip elines have been sub jected to co . P ip eline leak s happ en frequen tly. L oca ting leak po in t is a rro sion and w ea r, and som e have been op era ted beyond design li m its very i m po rtan t techn ique. Q u ick and accu ra te loca ting leak po in t cou ld ga

11、in ti m e fo r avo id ing acciden t and reduce the lo ss of m a2 . In th is p ap er, developm en t of a system to m on ito r the crude o il p ip eline is in troduced. Tw o m ethod s of loca ting leak po in t teria l a re p ropo sed: 1. In stan taneou s nega tive p ressu re w ave loca ting m ethod ba

12、 sed on a fa st d ifferen tia l a lgo rithm ; 2. Po la r co rrela tion . leak po in t loca ting. Exp eri m en ts in Sheng li O il2field show ed the accu racy and p ractica l va lue of the m ethod s Key wordsp ip eline leak loca ting d ifferen tia l a lgo rithm co rrela tion CAL CU LA T I N G PO T EN

13、 T I AL D ISTR I BU T I ON ON EXT ER I O R O F TAN K BO T TOM S B Y ANAL YT ICAL AL GO R ITHM ACTA 1998, 19 ( 3 . (P etroleum U n iv ersity , B eij ing L i X iangyi et a l T he po ten tia l d istribu tion of tank bo ttom s is an i m po rtan t index to app ra ise effectiveness of ca thod ic p ro tect

14、ion (CP . T heo 2 retica l ca lcu la tion of bo ttom po ten tia l is va luab le w hen m ea su rem en t is d ifficu lt o r i m po ssib le. T he po ten tia l va ria tion cau sed by flow ing cu rren ts a long tank bo ttom s is too sm a ll to have effect on po ten tia l d istribu tion. T he po ten tia l

15、 d istribu tion of tank bo ttom s m a in ly dep end s on g round electric field. T he equa tion of po ten tia l on tank bo ttom cou ld be derived from electric field theo 2 . W hen the anodes in CP a re fa r from the p ro tected tank, the rela tion sh ip of po ten tia l and d istance to bo ttom ry of stab le cu rren ts cen ter is si m p lified a s a th ird pow er p a rabo lic2like equa tion. T hese conclu sion s ha s been confirm ed by bo th labo ra to ry da ta and in situ m