川北石龙场大一气藏积液停产凝析气井复产技术

PRODUCTION RECOVERY TECHNOLOGY FOR CONDENSATE GAS SHUTDOWN WELLS DUE TO ACCUMULATION, DAYI GAS RESERVOIR OF SHILONGCHANG IN NORTH SICHUAN BASIN

石龙场大一凝析气藏主要产层为下侏罗统自流井组大安寨段,属于凝析气弹性驱动的裂缝性凝析气藏。目前该气藏已进入后期开发阶段,地层压力愈来愈低,气体携带凝析油的能力越来越弱。部分井因井筒积液严重、井口压力降较大而难以投产,影响了气井的正常生产。通过对凝析气藏开采后期因积液严重而停产的井的分析,认为该类井复产的关键:一是要降低井筒液柱压力梯度;二是井底要有足够的能量。根据分析结果,首先关井恢复地层压力,然后将压力相对较高的套压气快速倒入油管,使井筒液体产生较大扰动,天然气与凝析油充分混合起泡,在井筒中形成泡沫流,从而降低液柱压力梯度,有利于积液排出。采取措施后,积液停产井有效恢复生产,取得了显著的效果。

The major producing formation of Dayi condensate gas reservoir is Da'anzhai Member of Lower Jurassic Ziliujing Formation. It is an elastic-driven fractured condensate gas reservoir. During the later stage of development, the formation pressure becomes lower and lower, and the capacity of condensate oil carried by gas gets weaker and weaker. Some of wells can not be put into production because of serious accumulation in wellbore which brings large wellhead pressure drop for wellhead. Through the analysis of the shutdown wells in this reservoir, this paper describes two key points of production recovery for those wells: (1) the pressure gradient of wellhead fluid column should be reduced; (2) enough bottom-hole power. According to the analysis, a shut-in has been implemented primarily to recover the formation pressure. Then, casing pressure gas with higher pressure is put immediately into tubing. The gas decreases the accumulation height and makes big disturbance in wellbore to mix natural gas and condensate oil intensively until foamy. The foam-produced flow can reduce the pressure gradient so that the accumulation can be discharged. Therefore, the treatment has been applied efficiently to the shutdown wells to recover production.