Abstract
The effect of friction in well drilling operations is especially important in deviated wells and in cases where the impact of axial compressive loads on a drillstring decreases significantly with vertical depth and transversal displacement. The prevailing theories hope to determine the critical buckling loads analytically using the Paslay-Dawson equation with the hope of minimizing the event of tubular buckling in a principled way. In practice, there is very little that can be done to change the nature of a formation except to minimize the friction drag force by pumping friction reducers into the wellbore/borehole which consequently enhances the propagation of axial compressive forces. Determining the tubular lockup region accurately is possible with high fidelity and high-resolution friction profiling of the formation using models that determine critical buckling loads as a function of drag friction. Economically, it is important to determine ahead of time the friction factor or coefficient profile of a formation to establish if and where tubular lockup would occur, which consequently reduces drilling costs by pumping a friction reducer when it is needed and not before. The main idea of this paper is therefore to introduce a model that generates a high-resolution k-point friction profile for a formation using Markov chains. The model is then applied to predict the transition probabilities for friction drag in a reservoir with an accuracy of 86.8%.
