Study on drilling fluid technology for improving activated shale drilling rate

The problem of inhibition active shale hydration and dispersion for drilling water sensitivity formation has been attached a high degree attention. Shale dispersion can lead to hole shrinkage, wall collapse, bit balling, tripping resistance and pipe sticking. A suitable drilling fluid system was developed for activated shale drilling combined polyamine inhibitors with anti-accretion fast drilling additives. The drilling fluid can resist high temperature above 150 ℃ according to the experiment for anti-temperature rheological behavior of the fluid. The sodium bentonite make-slurry test, core collapse resistance test, shale cuttings recovery and accretion test show that the inhibitory property and lubrication performance are close to the oil-based drilling fluid performance, which can effectively prevent the drilling fluid viscosity-shear increasing, performance deteriorated when drilling strong make-slurry activated shale, and avoid shale borehole instability, cuttings dispersion, bit balling and sticky mud adhesion and accretion. The drilling fluid also has a good anti-pollution ability, biological non-toxic, and compliance with the emission standards. The successful application for Nanpu Well 17-×1511 shows the drilling fluid system has effectively solved the problem of safe and fast drilling for water-sensitivity formation and is suitable for further field application.