1.某井套管下入深度2000m,固井水泥浆返深700m。固井时井内钻井液密度1.35g/cm3,水泥浆密度1.90g/cm3,替浆液为钻井液。下次钻进时钻井液密度为1.56g/cm3。试按以下三种工况计算套管柱所受的外压力、支撑内压力及有效外压力,并给出各压力沿管柱变化示意图。(1)注水泥完毕,水泥浆仍是液态时。(2)下次钻进到3500m时发生井漏(地层盐水密度取1.07g/cm3)。(3)下次钻进发生井漏,套管内钻井液全漏空。解:(1)外压力0.009810.00981[7001.35(20001300)1.90]33.501ompHMPa支撑内压力0.009810.009811.35200026.487ibmpHMPa有效外压力33.50126.4877.014oeoibpppMPa(2)外压力0.009810.009811.35200026.487ompHMPa支撑内压力1.07(1)3500(1)1099.3591.56swLnnHHm0ibp(0)LHH0.00981()0.009811.56(20001099.359)13.783ibnLpHHMPa02004006008001000120014001600180020000.00010.00020.00030.00040.000深度m压力MPa压力沿管柱变化示意图外压力支撑内压力有效外压力有效外压力26.48713.78312.704oeoibpppMPa(3)外压力0.009810.009811.35200026.487ompHMPa支撑内压力0ibp有效外压力26.487oeoibpppMPa2.某气井井深5000m,采用139.7mm生产套管,预计产层压力为72MPa。固井时井内钻井液密度1.50g/cm3。试计算井口与井底的内压力、支撑内压力(地层盐水密度取1.07g/cm3)02004006008001000120014001600180020000102030深度m压力MPa压力沿管柱变化示意图外压力支撑内压力有效外压力05001000150020000.00010.00020.00030.000深度m压力MPa压力沿管柱变化示意图外压力支撑内压力有效外压力与有效内压力。如果以井口内压力进行套管的抗内压筛选,C-75钢级壁厚为9.17mm与7.72mm的长圆螺纹套管能否采用?解:井口内压力441.115101.115100.5550007252.987BPiHppMPaee井底内压力72iPppMPa支撑内压力0.009810.009811.07500052.484obswpHMPa有效内压力7252.48419.516ieiobpppMPaC-75钢级壁厚为9.17mm的长圆螺纹套管抗挤强度为58MPa,满足要求,能采用。C-75钢级壁厚为7.72mm的长圆螺纹套管抗挤强度为41.6MPa,不满足要求,不能采用。3.某段尺寸177.8mm、钢级K55、壁厚9.19mm、长800m的套管,下入深度1700m,某底端所受轴向拉力为300kN。固井时井内钻井液密度1.45g/cm3。试分别考虑与不考虑双向应力计算其底、中、顶三点出的抗挤安全系数(外挤压力按全掏空考虑,计算拉力时不考虑钻井液浮力)。解:查表得钢级K55壁厚9.19mm的套管q=0.3869kN/m,管体屈服强度Ts=1846kN,抗挤强度Pc=29.8MPa套管底部轴向拉力=300kN=300+0.3869400=454.76kN=300+0.3869800=609.52kNTTT底中顶(1)考虑双向应力,抗挤强度为22cc22cc2cc3133001300[1()]29.8[1()]27.082424184621846313454.761454.76[1()]29.8[1()]25.4434241846218.46313609.52[1()]29.8[1()4241846csscsscssTTppMPaTTTTppMPaTTTTppTT底底底中中中顶顶顶21609.52]23.63621846MPa抗挤安全系数cccccc27.082==1.1200.009810.009811.45170025.443==1.3760.009810.009811.45(1700400)23.636==1.8460.009810.009811.45(1700800)mmmpSHpSHpSH底底中中顶顶(2)不考虑双向应力,抗挤强度为cccccc300(1.030.74)29.8(1.030.74)27.1101846454.76(1.030.74)29.8(1.030.74)25.2621846609.52(1.030.74)29.8(1.030.74)23.4131846cscscsTppMPaTTppMPaTTppMPaT底底中中顶顶抗挤安全系数cccccc27.110==1.1210.009810.009811.45170025.262==1.3660.009810.009811.45(1700400)23.413==1.8290.009810.009811.45(1700800)mmmpSHpSHpSH底底中中顶顶6.试推导水泥浆密度ρ与干水泥密度ρc、配浆水密度ρw及水灰比m的关系式:=cwwcmm(1+)解:水泥浆密度ρ=ccwwcwmVVVVV总总(1)水灰比mwwccVmV(2)得wwccVmV(3)ccwwmVV(4)将(3)(4)带入(1)得=cwwcmm(1+)7.某井技术套管固井,套管尺寸244.5mm(598in),下入深度3160m,钻头直径311.2mm(1124in),裸眼段平均直径扩大率5%,上层套管下入深度2302m。套管柱由两段不同壁厚的套管组成:0~1780m,套管直径222.4mm;1780~3160m,套管内径220.5mm。浮箍位置(井深)3139m,设计水泥返深2100m。固井时井内钻井液密度1.38g/cm3,计划使用密度为1.10g/cm3的前置液15m3,水泥浆密度1.90g/cm3(水灰比0.44),水泥浆流变性测量数据为:θ300=175格,θ200=131格,θ100=76格,θ6=16格,θ3=11格。试设计和计算:(1)水泥用量;(2)替浆量;(3)注水泥紊流临界排量;(4)前置液全返出套管鞋时和顶替终了时环空井底静液压力。计算时不考虑裸眼段井径与上层套管内径的区别。解:因为平均井径扩大率为5%,所以裸眼段平均直径为311.21.05326.76hDmm水泥返深为2100m,故水泥固封段高度为316021001060hm浮箍位置(井深)3139m,所以水泥塞高度为3160313921phm口袋高度为0dh(1)水泥用量环空水泥用量为:222231()(32.67624.45)106039.1224000040000nslahiciVDDhm管内水泥塞体积为:22231()22.05210.8024000040000nslphiciVDDhm口袋水泥体积为221()040000nsldhiciVDDh水泥浆量为:339.1220.802039.922slslaslpsldVVVVm水泥用量为1.9039.92252.675110.44slcslWVtm(2)替浆量:222311.03[22.24178022.05(31601780)]126.5294000040000kydpiiKVDLm(3)注水泥紊流临界排量水泥浆流变参数3001003000.75921752.096lg2.096lg0.7592760.5110.5111750.7855511511nnnKPas水泥浆紊流的临界环空平均流速为12210.759220.759220.7592(34701370)840.01[][]1.2()(347013700.7592)0.785580.759240.01[][]1.21.900.7592(32.67624.45)3.038/nnnchcnKnnDDms如此高的返速,井下一般是不允许的。说明,水泥浆一般难于达到紊流状态。为提高顶替效率,一般采取前置液紊流技术。在上述返速下,环空水泥浆达到紊流的临界排量需要:2222333()(32.67624.45)3.0386.728/min20002000chccQDDm(4)前置液全返出套管鞋时和顶替终了时环空井底静液压力裸眼段环空面积为:22222()(32.67624.45)0.369074000040000hcDDm前置液计划用量为15m3,在环空所占高度为:150.36907406m所以,当前置液全返出套管鞋时环空井底静液压力为:0.00981[1.38(3160406)1.10406]41.664MPa顶替终了时环空井底静液压力:0.00981[1.38(31604061060)1.104061.901060]47.072MPa原来全为钻井液时,井底静液压力为0.009811.38316042.779MPa由此可见,与固井前相比,当前置液全返出套管鞋时,环空井底静液压力降低了1.115MPa;顶替终了时环空井底静液压力增加了4.293MPa。油气开采方向一班吕登宇12010104342015.4.8