非常规排液技术在长庆气田的应用

Application of unconventional liquid drainage techniques in Changqing gas field

长庆气田具有典型的低压、低渗、低产特征。气井实施压裂、酸化等储层改造措施后,依靠产出气携持作用和地层能量进行排液很难达到预期效果。排液时间长且不彻底,容易引起储层二次伤害和影响正常试气生产,必须采取有效的排液技术排出积液,以提高气井产量和确保稳产。基于现场试验,提出了几种非常规排液技术的现场应用,分析了各项技术的可行性,同时开展了现场制氮气举排液试验,并评价了其应用效果;试验表明,油管注气憋压排液和套放排液法适于套压较低的气井;油套连通排液适于部分油放不通而套压较高的气井;现场制氮排液相对成本低,效果明显,值得现场进一步推广。通过试验研究,为同类气藏现场排液技术的应用和决策提供了一定的参考。

Changqing gas field has the typical characteristics with the low reservoir pressure, low permeability and low production. Conventional liquid drainage technique can not reach the anticipated effect, which based on the output gas holding effect and the forma- tion energy. Because of the long drainage operation time and the halfway measures which could induce reservoir secondary damage and affect regular gas production test. Therefore, it is necessary to adopt efficient liquid drainage techniques to unload the bottomhole liquid and enhance the stable gas production. This paper has put forward several unconventional liquid drainage techniques in field use, analyzed their practicability, and operated the liquid unloading experiment of field nitrogen gas generation and gas lifting technique. The field experiments indicate that method of tubing gas injection hold pressure for draining and method of casing pressure relief for drain- ing are adapted to the gas well with low casing pressure; method of tubing connected with casing for draining is adapted to the well with higher casing pressure which can not unloading the liquid with tubing draining; method of field nitrogen gas generation for gas lifting has obvious effect with low cost, which is worth popularizing on field. Through the experimental research, it provides certain reference for the field application and decision-making on liquid drainage in the similar gas reservoir.