2 intervals of hole angle change 3 the casing in a

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Unformatted text preview: uding the hardness of each. It is not always possible to have proper designs for both strings and prevent the drill string being harder than the casing. 214 Copyright(c) 2005 by Ali Ghalambor & Boyun Guo 107 Bearing Load Considerations Side force is caused by: 1. Doglegs in the wellbore. 2. Intervals of hole angle change. 3. The casing in a buckled state. 4. Effective weight of drill string hanging below the point of contact. Casing can be prevented from buckling by: 1. Not allowing sufficient room outside the casing for buckling to occur. 2. Insuring that the axial loading in the casing string, as used, is algebraically greater than the stabilizing forces on the string. 215 Rate of Motion of Drillstirng to Casing The culprit that actually causes the casing to wear is the frictional energy created at the point of contact. The greater the rate of motion for a given load, over an area of contact, the greater the frictional energy generated. In instances where wear is a major consideration, downhole motors or turbines can be used to provide the rotational mo...
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This document was uploaded on 03/28/2014.

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