Schlumberger

Technical Paper: Rotary Steerable Technology Creates Value in Western Canadian Drilling Environment

Society: AADE
Paper Number: 09-ntce-05-04
Presentation Date: 2009
 

Abstract

In today's world, drilling is mainly driven by performance efficiency. Every operator strives to reduce the cost of drilling without compromising the quality of the wellbore. A low-quality wellbore can limit the life of a well by compromising the success of subsequent operations such as logging, casing, and fracture treatment.

One of the major challenges to wellbore quality in western Canada is directional control. The geological environment makes directional control difficult. Even vertical wells require some kind of control to stay vertical. A positive displacement motor (PDM) is the most common means of maintaining directional control in both vertical and directional wells. However, sliding is required to make directional changes with a PDM. Sliding exposes the drilling assembly to wellbore friction, thereby impacting the weight transfer to the bit. The combined effect of reduced weight on bit (WOB) and rotation speed results in loss of performance in the form of reduced rate of penetration (ROP). This effect is more pronounced when drilling with fixed cutter polycrystalline diamond compact (PDC) bits. Furthermore, the combination of rotating and sliding creates an additional tortuosity that may impact the quality of the borehole.

Rotary steerable system (RSS) technology is addressing these challenges with a design that maintains directional control without sliding. The entire drillstring is rotated from surface, thus keeping the wellbore friction at bay. Better weight transfer and consistent rotation speed at the bit result in consistent ROP and therefore consistent performance. With PDC bits, the performance improvement can be an order of magnitude.

RSSs have been in use in western Canada for the last few years. This paper reviews the drilling performance in Burnt Timber, Narraway and Big Horn/Saunders fields. It presents the methodology for selection of suitable candidates for RSS, the application of the methodology to the wells in the fields, and results of drilling performance, including comparisons with other wells drilled in the fields.