石油钻探技术
石油鑽探技術
석유찬탐기술
PETROLEUM DRILLING TECHNIQUES
2014年
6期
45-48
,共4页
许红林%张智%施太和%熊继有
許紅林%張智%施太和%熊繼有
허홍림%장지%시태화%웅계유
高温%高压%水泥环%理论模型%应力分析
高溫%高壓%水泥環%理論模型%應力分析
고온%고압%수니배%이론모형%응력분석
high temperature%high pressure%cement sheath%theoretical model%stress analysis
高温高压井中井筒压力和温度变化较大,会给水泥环的力学性能带来严重影响。基于弹性力学多层厚壁圆筒理论,建立了耦合压力、温度的水泥环力学理论模型,研究了水泥环中径向应力和切向应力的分布规律。研究表明:持续套管压力值为10~50 M Pa且井筒温度变化值为-50~50℃时,水泥环总体上沿径向受压,沿切向受拉,二者最大值均位于水泥环内壁;井筒温度变化值一定时,水泥环中径向压应力和切向拉应力随持续套管压力值的增大而增大;持续套管压力值一定时,水泥环中径向压应力和切向拉应力随井筒温度的升高而增大,随井筒温度降低而减小;井筒温度升高会加剧水泥环的切向受拉失效风险,井筒温度降低却可能导致水泥环径向密封失效。因此,高温高压井应考虑井筒温度变化对水泥环应力的影响,建议采用低弹性模量水泥浆固井,并提高水泥环与套管和地层的胶结强度,以提高水泥环的整体力学性能。
高溫高壓井中井筒壓力和溫度變化較大,會給水泥環的力學性能帶來嚴重影響。基于彈性力學多層厚壁圓筒理論,建立瞭耦閤壓力、溫度的水泥環力學理論模型,研究瞭水泥環中徑嚮應力和切嚮應力的分佈規律。研究錶明:持續套管壓力值為10~50 M Pa且井筒溫度變化值為-50~50℃時,水泥環總體上沿徑嚮受壓,沿切嚮受拉,二者最大值均位于水泥環內壁;井筒溫度變化值一定時,水泥環中徑嚮壓應力和切嚮拉應力隨持續套管壓力值的增大而增大;持續套管壓力值一定時,水泥環中徑嚮壓應力和切嚮拉應力隨井筒溫度的升高而增大,隨井筒溫度降低而減小;井筒溫度升高會加劇水泥環的切嚮受拉失效風險,井筒溫度降低卻可能導緻水泥環徑嚮密封失效。因此,高溫高壓井應攷慮井筒溫度變化對水泥環應力的影響,建議採用低彈性模量水泥漿固井,併提高水泥環與套管和地層的膠結彊度,以提高水泥環的整體力學性能。
고온고압정중정통압력화온도변화교대,회급수니배적역학성능대래엄중영향。기우탄성역학다층후벽원통이론,건립료우합압력、온도적수니배역학이론모형,연구료수니배중경향응력화절향응력적분포규률。연구표명:지속투관압력치위10~50 M Pa차정통온도변화치위-50~50℃시,수니배총체상연경향수압,연절향수랍,이자최대치균위우수니배내벽;정통온도변화치일정시,수니배중경향압응력화절향랍응력수지속투관압력치적증대이증대;지속투관압력치일정시,수니배중경향압응력화절향랍응력수정통온도적승고이증대,수정통온도강저이감소;정통온도승고회가극수니배적절향수랍실효풍험,정통온도강저각가능도치수니배경향밀봉실효。인차,고온고압정응고필정통온도변화대수니배응력적영향,건의채용저탄성모량수니장고정,병제고수니배여투관화지층적효결강도,이제고수니배적정체역학성능。
Significant changes of the wellbore pressure and temperature in HPHT wells may bring great chal‐lenges to the mechanical integrity of the cement sheath .On the basis of the multi‐layer thick wall cylinder theory of elastic mechanics ,this paper proposed a mechanical theoretical model of cement sheath under both pressure and temperature ,and investigated the distribution of radial and tangential stresses within cement sheath .Results of studies demonstrate that when the sustained casing pressure (SCP)is 10‐50MPa and wellbore temperature change (WTC)is -50‐50℃ ,the cement sheath is generally radially compressed and tangentially tensioned ,and the maximum compressed and tangential stresses are both at the inner wall of the cement sheath .When the WTC keeps constant , both stresses increase with the increase of the pressure inside the casing .When the SCP is constant ,both stresses in‐crease with the increase of the WTC and decrease with the decrease of the WTC .A wellbore temperature increase will aggravate the possibility of tangential tensile failure in cement sheath ,and a wellbore temperature decrease will lead to its failure due to radial tension .Consequently ,wellbore temperature changes should be considered for their effect on the stress of the cement sheath ,and the cement with lower elastic modulus and higher bond stength with casing and for‐mation should be used to enhance the comprehensive mechanical performance of cement sheath in HPHT wells .