火驱重力泄油水平井油管的失效原因
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摘要
火驱重力泄油生产过程中,水平井是唯一的泄油排气通道,井下油管长期处于200～300℃、CO_2环境中,间歇出现高温和高含量氧气。对某水平井断裂油管的理化性能、金相组织、断口微观形貌及腐蚀产物进行分析,探究了油管断裂的原因。结果表明:断裂油管失效机理为高温蠕变断裂,因局部长时间经历高温退火导致管体组织老化,屈服强度和抗拉强度均远低于标准,在轴向拉应力作用下,管体发生蠕变断裂,同时管体内外壁发生高温氧化导致壁厚减薄,加剧油管断裂。
In the process of fire-flooding gravity drainage, the horizontal well is the only oil-exhaust and exhaust passage. The downhole oil pipeline is long-term serviced in the temperature ramge of 200 ～300℃ and CO_2 environment, intermittent high temperature and high oxygen content may appear. The physicochemical properties,metallographic structure, fracture morphology and corrosion products of a horizontal well fracture tubing were analyzed,and the causes of tubing fracture were explored. The results show that the failure mechanism of the fractured tubing was high temperature creep rupture. The aging of the tubular structure was caused by localized high temperature annealing for a long time. The yield strength and tensile strength were much lower than those of the standard. Under the axial tensile stress, the tubular body creeped and then fractured, and high temperature oxidation of the inner and outer walls of the tube caused thickness of the wall to be thinned, which aggravated the fracture of the oil pipe.
In the process of fire-flooding gravity drainage, the horizontal well is the only oil-exhaust and exhaust passage. The downhole oil pipeline is long-term serviced in the temperature ramge of 200 ～300℃ and CO_2 environment, intermittent high temperature and high oxygen content may appear. The physicochemical properties,metallographic structure, fracture morphology and corrosion products of a horizontal well fracture tubing were analyzed,and the causes of tubing fracture were explored. The results show that the failure mechanism of the fractured tubing was high temperature creep rupture. The aging of the tubular structure was caused by localized high temperature annealing for a long time. The yield strength and tensile strength were much lower than those of the standard. Under the axial tensile stress, the tubular body creeped and then fractured, and high temperature oxidation of the inner and outer walls of the tube caused thickness of the wall to be thinned, which aggravated the fracture of the oil pipe.
引文
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[3]谷涛,胡斌,王强,等.典型金属材料高温蠕变剩余寿命评价方法[J].中国计量大学学报,2017,28(2):176-184.
[2]万金成,付朝阳,马增华,等.油气井高温高压CO_2/O_2腐蚀研究进展[J].全面腐蚀控制,2014,28(2):39-43.
[3]谷涛,胡斌,王强,等.典型金属材料高温蠕变剩余寿命评价方法[J].中国计量大学学报,2017,28(2):176-184.