Research on optimum drilling string assembly design for extra deep hole drilling

Abstract:

The drill string is the core and key technology in deep land and deep water drilling for deep earth exploration; however, with the limited allowable drilling depth, the drill string of a single specification is difficult to meet the design requirements of 10000m extra deep continental scientific drilling and deep ocean drilling. In this paper, by reducing the weight of the lower portion of the drill string and improving the strength of the upper portion, the design of the drill string assembly is optimized. With the priority of tensile strength calculation, the demand on the drill string strength is satisfied in consideration of the safety factor and tensile allowance in case of dynamic loads and other complex situations, and the software for the drill string assembly design and safety coefficient calculation is developed, which can realize the drill string assembly design and safety coefficient calculation for different hole depths and drill rod structures.