The Prevention And Cure Of Bit Balling In Water Based Drilling Fluids

With an increasing focus on drilling performance and economics, as well as a move towards compliance with more stringent environmental demands, there has been a move towards a greater usage of new and more highly inhibitive water based drilling fluids, often to replace invert emulsion fluids. Such fluids have endeavored to utilize novel chemistry to minimize the interaction of the water based fluid with water sensitive shales, resulting in greater levels of wellbore stability, hole gauge, reduced dilution rates and improved drilling economics. One unfortunate result of this move has been an increase in the incidence of bit balling and cuttings accretion, which has resulted in lost time, reduced drilling rates and often expensive remediation operations. This paper reviews recent developments in the areas of both the remediation and prevention of bit balling and shale accretion in water based drilling fluids. The paper describes the mechanism of bit balling and cuttings accretion, the influence of clay type, fluid chemistry, and drilling parameters and also gives guidelines for minimization of bit balling potential. In addition to discussing testing protocols for evaluation of bit balling potential, field results obtained from usage of a modern day bit balling prevention additive are presente