Construction of Ultralong Wells Using a Catenary Well Profile

Abstract

Abstract This paper presents analysis and design of ultra-long wells using a catenary well profile. Ultra long wells have a considerable economic potential as remote reservoir pockets can be drained from existing platforms. There is however, a high economic risk for these wells, many drilling issues must be resolved. The paper presents results from a project undertaken to explore the limits and the potential for ultra-long wells. Wellbore friction is an important issue, and to analyze this a complete catenary model for design of wellpath, drill pipe loads and torque and drag forces are developed. The new model is analytically exact. Standard build profile is compared with a catenary profile. It is shown that the catenary is not as favourable as expected due to friction in the entrance to the catenary, except that friction reduction measures can be applied over a smaller area. Application of light weight drill pipes is more important to reduce load and torque. Both 10 km and 15 km horizontal departure wells are compared. The study shows that a 15 km horizontal departure well can be drilled with existing equipment and modern drilling units.