低密度高抗油泡沫钻井液研究及在低压油气井的应用

RESEARCH AND APPLICATION OF LOW DENSITY & HIGH OIL- RESISTANT FOAM DRILLING FLUID IN LOW PRESSURE WELLS

使用高抗油发泡剂,在含有高比例原油的钻井液中发泡,研制成一种低密度高抗油泡沫钻井液,泡沫半衰期可达到480 min,泡沫密度最低可降至0.35 g/cm3,井筒循环当量密度可控制在0.85~0.95 g/cm3,钻井液各项性能优于常规水基泡沫钻井液。由于具有较低的当量密度,该钻井液具备在低压油气井实施欠平衡钻井作业的条件。该钻井液在吐哈油田5口低压油气井储层段应用,有效减少了水敏性储层的伤害,具有很好的储层保护效果,同时大幅度提高了机械钻速。低密度高抗油泡沫钻井液技术为低压、低渗、强水敏储层的动用开发提供了强有力的技术支持。

By using high oil resistant loamer in high ratio crude oil drilling fluid,a kind of low density and high oil-resistant foam drilling fluid has been developed.The experiment results showed that the half foam life period of the high oil-resistant foam drilling fluid was high up 480 minutes,and the density could be reduced to 0.35g/cm^3,the equivalent circulating density could be controlled in 0.85-0.95g/cm^3,and the other performances were superior to conventional water- based foam drilling fluid.Because of lower equivalent density,the high oil- resistant foam drilling fluid was fit for underbalanced drilling of low pressure oil and gas wells.The drilling fluid has been used in five low pressure oil and gas wells in Tuha Oilfield,it effectively reduced the damage of water sensitivity reservoir,had good reservoir protection effect and increased the rate of penetration.