Investigation of a quasi-static deformation can give important insights into a number of different aspects of directional drilling including: levels of stresses and strains developed and directional tendencies. Physical tests are carried out on a horizontal model made of poly (methyl methacrylate) (PMMA) and scaled according to Froude principles. The effects of weight on bit (WOB) and torque on bit (TOB) are investigated. It is shown that when subjected to WOB and TOB the deformation of the model is three-dimensional, with WOB affecting mostly the deformation in the horizontal plane, whereas TOB has a significant effect on the vertical plane. Axial shortening due to WOB and TOB is also reported. However the effects of WOB are an order of magnitude greater than those of TOB.

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