Unusual stresses require attention to bit selection

The unique stresses imposed on a rock bit during horizontal drilling can often have detrimental effects if operating parameters are not addressed thoroughly and a bit program developed accordingly. A number of phenomena either acting collectively or singularly can severely hamper the overall success of the program. These phenomena can be a function of the deviated well path, the formations encountered, or the increased use of downhole steerable motors and topdrive systems. While bits may be a small portion of overall well costs, improper selection can have an adverse effect on the outcome of a horizontal program. This paper deals with many of the considerations for selecting bits for horizontal drilling.