辽河油田热采井套损防治新技术

New technology for casing damage prevention and cure of thermal production wells in Liaohe Oilfield

辽河油田稠油热采过程中套管损坏严重。经大量调查研究认为,造成套管先期损坏的原因是:热应力大,油井出砂,API圆螺纹接头和偏梯形螺纹接头不适合热采井要求,水泥封固质量不好,水泥环空段套管易变形,隔热管和隔热措施不力。采取的措施有:提拉预应力,用N80偏梯套管取代普通套管,使用热采专用水泥返到井口,用良好的隔热管。治理后热采井套管损坏虽有所下降,但套管先期损坏依然严重。采取的新措施主要是:用热应力补偿器减少注蒸汽时套管应力,用TP100H套管以增强抗热变形能力,用TP120TH外加厚套管解决油层套管因出砂和射孔引起的套管轴向应力问题。经过长期的研究与实践,减缓了热采井套管先期损坏速率。

The casing damage was serious during the thermal production in Liaohe Oilfield. Through investigations and researches, reasons for the initial casing damage were determined as follows; higher thermal stress, sand production in oil wells, unfit sub with API round thread and bias buttress thread, low cementing quality, easily appearing casing deformation in cementing annular section, and improper heat insulation tubing and heat insulation measures. The measures adopted are: prestress pulling up, substituting N80 casing with bias buttress thread for the common casing, using special cement for thermal production wells and returning to the surface, and utilizing fine heat insulation tubing. After the management, the casing damage in thermal wells was decreased, but the initial casing damage was still heavy. Thus new techniques were adopted: reducing the casing stress during steam injection using heat stress compensate tool, increasing the deformation resistance using TP100H casing, and solving hoop stress problems of production casings caused by sand production and perforation using TP120TH external upset casing. Through the long-term researches and practices, the initial casing damage rate of thermal wells was reduced.