川东石炭系低压气井解堵工艺研究与应用

川东石炭系气井生产时间长,部分气井出现不同程度的井筒堵塞影响产能,常年反复酸化导致气井井周形成大的近井酸蚀通道,酸液未发挥作用就已漏失,酸化效果差且稳产周期短。鉴于目前川东石炭系气井解堵难的问题,通过井筒堵塞物分析明确了堵塞物主要由铁的氧化物、碳酸盐、BaSO₄和SiO₂等无机物和月桂醇聚醚类有机物组成,推荐的解堵工作液体系(15%(w)HCl+1%(w)缓蚀剂+2%(w)铁稳剂+3%(w)表面活性剂)在地层温度下对垢物的溶蚀率最高达77.6%。对不同堵点位置的堵塞提出了针对性的解堵工艺,油管堵塞推荐连续油管或油管注酸解堵,套管堵塞推荐真空回位抽砂工艺,地层堵塞推荐泡沫酸酸化解堵。采用研究的解堵液体系和工艺开展现场试验6口井,解堵有效率100%,为本区和同类型低压气井解堵提供了有效的技术手段。 

Research and application of blockage removal technology for low-pressure gas well in eastern Sichuan carboniferous formation

These are different degrees of wellbore blockage which affects productivity due to long time production in gas well of eastern Sichuan carboniferous formation. Perennial acidizing stimulation leads to the formation of large acid-corrosion channels around wellbore. The acid flowed away directly without any effect, resulting in poor acidification efficiency and short stable production period. The analysis shows that the blockages are mainly composed of iron oxide, carbonate, barium sulfate, silica, and lauryl alcohol polyether organics. The dissolution rate of the blockage removal acid solution to scale at formation temperature is up to 77.6%(15%HCl+1% corrosion inhibitor +2% iron stabilizer +3% surfactant).Specific blockage removal technologies are proposed for different blockage place, coiled tubing or tubing injection for tubing blockage removal, vacuum backposition sand pumping process for casing blockage, the foam acidizing technology for formation plugging. Field tests were carried out in 6 wells, the effective rate was 100%, which provides an effective technical means for blockage removal of low-pressure gas wells in this area and the same type.