New Rotary Steerable Drilling System Delivers Extensive Formation Evaluation for High Build Rate Wells

Abstract

A new high build-up rate (HBR) rotary-steerable drilling system (RSS) with comprehensive logging-while-drilling (LWD) capabilities was developed and commercialized. The new HBR RSS was designed to provide extensive LWD services, including propagation and deep resistivity, neutron and density porosity measurements, borehole imaging and many others at build-up rates up to 12°/100 ft. Using closed-loop control and a short steering sleeve that decouples steering functionality from drilling dynamics, the system can perform open-hole sidetracks and drill high dogleg severity (DLS) curves and laterals in one run with precise directional control and well placement, without exceeding the fatigue limits of the LWD tools. In many areas around the world, rotary-steerable systems have replaced steerable motors because of the inherent advantages of RSS technology [1], including improved directional control, reduced wellbore tortuosity [2] and comprehensive logging-while-drilling (LWD) measurements. However, some applications require drilling and evaluating wellbores with higher build-up rates (BUR) than possible with a standard RSS. Developments in drilling tool design have increased the achievable BUR of rotary steerable systems to values on par with those of steerable motors. This achievement introduces a challenge related to the bending loads of the sophisticated LWD tools positioned behind the HBR RSS. When run with a steerable motor, the high bending loads on the LWD tools are primarily in static, because the curvature is created in a sliding mode of the drillstring. When run with a HBR RSS, the LWD tools are exposed to high cyclic bending loads because the string is constantly rotating. As a result of this challenge, the selection of LWD measurements available in HBR RSS applications is very limited. The authors present the design, simulation criteria and commercial results of the new HBR RSS in several operating environments, including the Western region of the USA and the Middle East. Drilling high DLS curves increased the length of laterals by several hundred feet, enabling additional reservoir exposure and ultimate recovery. The system drilled entire sections in one run and improved operational efficiency by the elimination of sliding. If formation tops arrived unexpectedly, or faults were encountered during geo-steering, the new HBR RSS system reduced the out of zone depth interval, thereby increasing recoverable reserves. The innovative HBR RSS system is used in many applications around the world to drill and evaluate complex wells with high DLS, as well as straight laterals, with precision and efficiency. Lessons learned during the commercial application of this functionality and technologies are presented with the industry to ensure the maximum value is achieved in the shortest amount of time possible.

Buckling modal analysis of a rotary steering drilling tool

“…This oil and gas development situation has forced the emergence of special process wells such as high-difficulty directional wells, cluster wells, and horizontal wells and has been widely used in the field [1] . Due to its low drilling speed and low deflection efficiency, the traditional conventional power drilling assembly no longer meets the drilling needs under the current development requirements [2] . The development of rotary steering drilling technology is well adapted to the needs of today 's oil and gas development.…”

“…In 1950, Lubinski simulated the buckling of a drill string in a deviated hole, derived the formula for calculating the critical buckling load of the drill string in the deviated well, and considered the effect of the differential pressure inside and outside the drilling fluid on the critical buckling load of the drill string [3] .…”