Abstract

In order to address various wellbore challenges, there has been improvements in methods of drilling and other wellbore activities since a long time. While the industry focuses on improvements of different methods, reducing Non Productive Time (NPT) has also become of great interest. Amongst many, one method to address the problem of drilling through fluid loss zone and to minimize casing running time and other NPT is Casing While Drilling (CwD). It is a method of drilling in which the conventional drill pipes are replces by the casing itself. During implementation of this method, there have been several observations of enhanced wellbore strength, pressure containment, better fluid loss control, etc. Plastering effect is considered to be the factor behind this, where the fine drill cuttings physically collide with the wellbore to form a stable mud cake layer that provides additional wellbore strength. Though plethora of work has been carried out, exact phenomenon of plastering effect is uncertain. Particle Size Distribution (PSD) of the drill cuttings along the wellbore is noted to play a crucial role is proper plastering effect. Authors of this paper, attempt to quantify the PSD in CwD that takes place during plastering effect. The work is expected to help in understanding the crushing effect and the background of fluid loss prevention.

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