SPE Members Abstract Some of the needs in directional drilling of extended reach and horizontal wells are discussed. It is forecast that Steerable Rotary Drilling (SRD) will meet some of these needs, providing economic benefits. Known options for an SRD system are briefly discussed. The system devised uses synchronous polyphase modulation of bias from a mechanism connected to, and rotating with, the drill bit, powered by drilling fluid and controlled by a directional sensor package, the orientation of the latter being independent of 8HA rotation, stabilized and controlled. This scheme meets structural requirements while being capable of development for a wide range of hole sizes The concept was proved by drilling an interval of 638m (2092ft) with an experimental SRD system. Deviation, while rotating, was controlled at rates up to 8.50/30m (8.60/100 ft) to change elevation up/down and azimuth left/right. The system was successful with both PDC and roller cone bits and the deviation rate vector was largely independent of bit weight. rotary speed and penetration rate. The drilling trials have provided data for a product aimed particularly at extended reach and horizontal drilling. Economic benefits are expected by saving time and by improving directional control. INTRODUCTION. Trends in directional drilling. Benefits of Extended Reach and Horizontal drilling. In developing drilling techniques, attention has traditionally been focused onto reducing "cost per foot". This is only one component of the more fundamental economic target of reducing cost per barrel. In recent years, the economic benefits of extending lateral reach capability in deviated drilling have been clearly recognised. In some cases, it is even feasible to develop offshore reservoirs from land, eliminating costly offshore platforms. The potential benefits of fewer platforms are illustrated by examples of savings quoted of $183 million in Wytch Farm, Southern England, and up to $100 million at Pt. Pedernales, offshore California. A related development is that of horizontal drilling. This can also reduce the cost per barrel, despite the higher cost per foot and feet per well. Extending lateral reach capability of deviated (including horizontal) wells depends on several interacting critical technologies. These have been widely reviewed, for example, by Payne, Cocking and Hatch, who also give many other relevant references. P. 435

TX 75083-3836, U.S.A., fax 01-972-952-9435.

This paper reviews how the Rotary Steerable System (RSS) market has changed over the last two decades. It explores current market forces; specifically the shift in RSS philosophy resulting from ever-improving motor steerable technology. It describes how the need for longer laterals with minimal tortuosity, maximum drilling efficiency, reduced risk of unplanned events, and elimination of AFE overspend, along with the paradigm shift in the directional drilling market seen since 2014, drove the specification for a new-generation RSS tool. The paper describes the development of a new RSS with a topology and control concept that allows full proportional control of bias from a fully rotating, push-the-bit tool, with the ability to "turn off" any bias during operations where side force is undesirable and to minimize potential tortuosity. It describes how the design team focused on modular design and rapid turn around of tools, in order to maximize utilization and efficiency. Field-test results are included, which demonstrate build and turn at up to 10°/100 ft. and the ability to drill accurate lateral sections. Field results also include the use of ultrasonic imaging while drilling to investigate hole quality.

A new edge preparation of Polycrystalline Diamond Compact (PDC) cutters has been developed to target applications where either weight or torque is limited. This paper describes the geometry, which differs considerably from existing thermostable product.Initial testing at atmospheric conditions in a drilling laboratory shows a 30% reduction in torque and a 100% increase in penetration rate when compared to conventional cutter geometry. Secondary testing was conducted with drill bit designs at a non-commercial test facility. In this controlled environment, designs with new cutter edge geometry were compared directly to those with conventional cutters. By using the same drill bit cutting structure and parameters, any difference in torque and penetration rate was solely dependent upon the cutter geometry. Additionally, to quantify any effects caused by torsional or lateral vibration, a downhole dynamics recorder was used to gather data at a high frequency sample rate.Performance studies are presented for a variety of applications from around the world but focusing on applications within the US Rockies. They compare direct offset runs against conventional geometry cutter designs. Results demonstrate that the new geometry delivers footage and ROP equal or greater than the best field offsets.The increased penetration rate and reduced torque provided by this geometry result from more efficient failure of the rock. This provides reduced Mechanical Specific Energy and improved drilling efficiency, thus reducing drilling costs for the operator. This is a significant step change in PDC cutter technology, dramatically increasing fixed cutter drill bit performance.

No abstract