China United Coalbed Methane Co., Ltd. College of Petroleum Engineering, China University of Petroleum

为了解决沁南示范区煤储层井壁易坍塌、钻井液易污染煤储层等难题,通过室内试验,对超低渗透钻井液处理剂和润滑剂进行了优选及评价,研选出超低渗透处理剂DL-1和环保型润滑剂SD-302:膨润土基浆中加入质量分数为2%的DL-1,在120℃老化16 h,煤粉床侵入深度7.33 cm,DL-1处理剂的主要性能优于国外同类产品;润滑剂SD-302在常用质量分数范围内(1%~3%),摩擦因数降低率在72.4%~87.7%。基于DL-1和SD-302,提出了中空玻璃微球低密度钻井液新配方。相对于原配方,改进的钻井液配方的润滑系数更低,为0.041,有利于降低定向井及水平井钻进过程中的阻卡或卡钻现象。新配方对不同渗透性储层的封堵效果更好,具有良好的防塌性能和保护储层作用。应用改进的中空玻璃微球钻井液在沁南示范区进行了2口定向井的现场试验,防漏失效果明显,防塌性能好,保证了钻井施工的顺利进行。

In view of the collapsibility of borehole wall and coal reservoir pollution resulted from drilling fluid in Qinnan demonstration plot, and based on the resear chin 11 th Five-Year, the ultra low permeability drilling fluid agent and lubricant were optimized and evaluated through laboratory experiments, and the ultra low permea bility dilling fluid agent DL-1 and the environmentally friendly lubricant SD-302 were selected. Adding DL-1 with the mass fraction of 2% in bentonite slurry, and aging a t 120。C for 16 hours, invasion depth of coalbed is 7. 33 cm, which is superior to the performance of similar foreign products. In the common mass fraction range ( 1% ~ 3%) of lubricating agent SD-302, friction coefficient reduction rate is 72. 4% ~ 87. 7%. A new formula of hollow glass microsphere low density drilling fluid is developed using the DL-1 and SD-302. Compared with the original formula, the improved new formula of drilling fluid has a lower lubrication cofficient of 0. 041, which is benefici al to reduce the phenomenon of blocking or sticking. The new formula has better sealing effect on different permeability of reservoir, and has better anti collapse perfor mance and protecting effect on reservoir. The improved drilling fluid has been applied in two directional wells for field trial at Qinnan demonstration plot, which proved t he drilling fluid had good performances of preventing leakage and anti collapse, and ensured the smooth construction of drilling.