Oil-based drilling fluids have long been recognized as a sound technical answer to problems encountered in deep-hot holes and, more recently, to stabilize boreholes with thick intervals of reactive clay formations. However, oil-based mud product development was slowing down until the introduction of low toxicity base oils in the late seventies created a need for new investigations. This innovation sparked a resurgence of oil mud research and development which has resulted in oil-based mud (OBM) systems being used routinely in many active drilling areas worldwide.
The mixing system makes possible improvements and presents case histories of field applications.
Fracturing operations have been improved by
(1) Mixing fracturing slurries under microprocessor control,
(2) Applying new baffle and agitator design concepts, and
(3) Using new methods for achieving rapid material wetting.
The rotating separator process is based on a different principle than the shale shaker process. The mud line flow is fed into the slowly rotating separator. The drilling fluid contaminated with drilled cuttings is fed into the centre of a screen coated drum as shown schematically in Fig. 1. The outside of the drum is connected to an under-pressurised ventilation system.
The combination of fast drilling, gumbo clay, and conventional solids control equipment operations can create a variety of issues:
- High losses of drilling fluid through the solids control units.
- High volume of dilution.
- High volumes of fluid processed requiring strictly regulated disposal to protect the environment.
- Continuous plugging of the mesh in the solids control units.
- Increase in the consumption of screens.
- Fluid overflow due to plugging of the screw conveyors.
- Poor supervision of the solids control units.
- Increased operating costs.