Drill collar connection failure frequency increases when wells are drilled deeper and when directional holes are drilled. These failures, which materially increase the cost of operations, prompted a study to find the best way to make up drill collar connections for achieving maximum joint life. This paper discusses the results of an investigation conducted by Texas A&M University Research Foundation to (1) determine from laboratory tests the optimum makeup torque for a select number of typical drill collar connections, (2) develop an analytical method of calculating optimum makeup torques for all sizes and types of drill collar joints, and (3) compare the laboratory derived torque makeup with those predicted by the analytical method. The close correspondence of the laboratory and analytical values supports the use of the analytical method for predicting torque makeup for those sizes and types of drill collar joints not tested in the laboratory.

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