元坝地区高密度钻井液CO_2污染处理技术

CO_2 Contamination Treatment Technology of High Density Drilling Fluid in Block of Yuanba

川东北元坝地区气藏埋深大,地层压力和温度高,且从陆相千佛崖组到海相长兴组均含有不同程度的CO2流体。在前期几口井的施工过程中,高密度钻井液受到CO2污染后出现严重增稠、流动性变差和泵压升高的现象,处理十分困难,严重影响了钻井施工效率。通过室内实验研究,形成了采取稀释降黏,防止钻井液继续稠化的处理技术,该技术可以解决常规石灰水难以处理的CO2污染引起的钻井液增稠问题,处理后的被CO2污染钻井液具有良好的高温稳定性,且具有更强的抗污染能力,其抗盐达10%、抗钙达1%、抗高含钙地层水达10%。在元坝29-1和元坝101-1井等应用后,取得了良好的降黏防稠化效果。

In block of Yuanba,the gas reservoir is buried deeply,the formation pressure and temperature are high,and CO_2 fluid is found in different formations.In some offset wells,the high density drilling fluid is thickened severely after contaminated by CO_2.Through laboratory experiments,the treatment technology of preventing thickening is developed to deal with the problem caused by CO_2 contamination that lime water can not resolve it effectively.Moreover,after treated by that,the salt tolerance is 10%,the calcium tolerance is 1%,and the calcium formation water is up to 10%.The applications in wells of Yuanba29-1 and Yuanba101-1 are successful.