超深水平井尾管悬挂器下部环空压力预测及其应用

超深水平井多封隔器分段改造作业过程中,井筒温度下降造成尾管悬挂封隔器下部环空压力下降,易造成尾管悬挂封隔器、下部分段改造封隔器和油管柱失效。针对典型分段改造水平井井身结构,开展分段改造过程中尾管悬挂封隔器下部环空压力变化的影响因素和潜在后果分析,综合考虑油管柱鼓胀效应引起的环空体积变化、井筒压力温度变化引起的环空流体体积变化和井筒温度变化引起的油管柱体积变化对尾管悬挂封隔器下部环空压力的影响,建立了尾管悬挂封隔器下部环空压力变化预测模型。以塔里木油田一口超深水平井为例,开展了分段改造过程中尾管悬挂封隔器下部环空压力预测,并在此基础上开展了封隔器和改造管柱力学分析。分析结果表明:超深水平井分段改造过程中,由于井筒温度场急剧下降,尾管悬挂封隔器下部环空压力相对坐封工况将发生大幅下降,从而给改造管柱和封隔器带来非常大的失效风险,超深水平井分段改造管柱设计过程中必须充分考虑该因素。

Prediction and application of lower annular pressure of hanger of ultra-deep horizontal well

During multi-packer segmented transformation of ultra-deep horizontal wells, temperature drop of shaft will cause drop of lower annular pressure of packer of tail tube hanger, which is easy to cause failure of packer of tail tube hanger, packer for lower segmented transformation as well as tubing string. In regard of the structure of horizontal well in typical segmented transformation, the analysis of affecting factors and potential consequences of change of lower annular pressure of packer of tail tube hanger during segmented transformation is developed, and full consideration is taken into for the influence on lower annular pressure of packer of tail tube hanger by annular volume change caused by ballooning effect of tubing string, annular fluid volume change caused by change of shaft pressure and temperature and volume change of tubing string caused by change of shaft temperature to establish a prediction model for change of lower annular pressure of packer of tail tube hanger. An ultra-deep horizontal well of Tarim Oilfield is taken for example to develop prediction for lower annular pressure of packer of tail tube hanger during segmented transformation, and mechanical analysis is developed for packers and tubing strings under transformation on this basis. The analysis results show that, during segmented transformation of ultra-deep horizontal wells, sharp drop of shaft temperature field will greatly lower relative setting conditions of lower annular pressure of packer of tail tube hanger, thus to bring about high risk of failure to tubing strings and packers under transformation. Therefore, it is necessary to take into full consideration of such factors in design of tubing string during segmented transformation of ultra-deep horizontal well.