一种适用于欠平衡钻井的充气泡沫钻井液

欠平衡钻井技术的关键是控制钻井液密度．使井内液柱压力小于储层孔隙压力。介绍了一种适用于欠平衡钻井的充气泡沫低密度钻井液。该充气泡沫钻井液在固体矿产勘探和热气田开采等方面取得了较好的应用效果。这种钻井液为气、液、固三相体系．泡沫剂选用DF-l，稳泡剂为一般的有机高分子聚合物。根据欠平衡钻井要求。通过对粘土、聚合物和泡沫剂的加量进行正交试验，优选出了若干组充气泡沫钻井液配方。应用表明，该充气泡沫钻井液泡沫稳定、密度低、液柱压力小、流变性好、携带岩屑能力强，有一定的抑制地层粘土矿物膨胀分散的能力和抗高温抗污染能力，可以作为欠平衡钻井介质进行试验应用。

An aeration foam drilling fluid used in underbalanced drilling

Underbalanced drilling means that drilling fluid pressure is less than reservoir pore pressure, and its technical key is the drilling fluid density controlling. An aeration foam drilling fluid used in underbal-anced drilling is presented. The fluid is a three-phase system composed of air, liquid and solid and its foa- ming agent is DF and stabilizing agent is a common organic high molecular polymer. A group of formulations have been optimized based on cross experiments on the dosage of clay, polymer and foaming agent according to underbalanced requirements. In both aspects of solid mineral exploration and hot gas field development , the fluid has been effectively used and results showed that the fluid has many advantages such as stable foam, low density, low liquid pressure, good rheology property, strong ability for carrying cuttings, high thermal stability, strong inhibition and good resistance to fouling. The drilling fluid can be used as a testing medium of underbalanced drilling in field.