Abstract
KCA Drilling is incentivised under their lead contractor relationship with Shell Northern Business Unit (NBU) to introduce such technology as can be economically justified to improve drilling performance. One of the ways this aim was achieved in 1997 was the investigation and introduction of alternative BHA technology. One technology that has been introduced is Steerable Rotary Drilling (SRD) which was undertaken in late 1997 to improve on the overall ROPs observed with bent subs and mud motors. This technology was perceived by Shell Well Engineering as becoming a high priority due to the increasingly complex wells being drilled in the NBU. The tools were used in the 8 ½" hole section through a combination of Cretaceous shales and Jurassic sandstone formations on two wells. There have been some successes and some important learning points from the initial campaign which involved the drilling of around 15,500 ft of 8 ½" hole with the new technology across two wells. Quantitative information on achieved ROPs, rotary speed requirements, doglegs achieved and the Mean Time Between Failure (MTBF) of the SRD tool are detailed in the text. This paper details the benefits of SRD technologies in low dayrate environments and the prospects of enhancing overall drilling performance thereby reducing the costs of marginal wells. The paper also details a consistent approach for selecting suitable well candidates for the application of rotary steering technology in comparison to oriented steering based on an equation that incorporates technical factors including ROP, rig dayrate and SRD tool economics. The paper also explains ongoing work to improve and enhance the SRD tools further for more demanding applications. It also details the effects the alternative BHA characteristics are having on other technologies in the oil industry e.g. PDC bit design and cementing.
