Press Esc to close



For full content view: Log in Now!

  • United Kingdom: The motor/VGS combination comes of age

    The introduction of rotary steerable systems (RSSs) has been heralded – especially by the major directional companies – as the beginning of a new directional drilling age, and in many ways it is. Keeping the assembly turning cleans the hole more efficiently, reduces the chance of sticking and, ultimately, allows drilling further than sliding with a downhole motor. These new tools allow the driller to make subtle corrections as he builds and drops angle, turning left and then right as he follows the geologist's requirements. The only real glitch is getting enough power to the bit from the surface to keep a reasonable ROP. Sometimes, running a motor is preferable. As ever, engineering is never as clear-cut as one might want. Usually, new tools come with compromises, and this is also true of rotary steerable systems. When working at peak performance in ideal formations for building angle, where excessive vibration, wear and temperature are not a problem, the RSS can perform admirably. With motors still seen as more reliable than RSSs, and some deepwater rigs costing $200,000 per day and more to operate, pulling out of hole from 15,000 ft because a drive shaft has snapped, a pad has fallen off or some other problem becomes an important decision. With RSS prices ranging from $10,000 to $25,000 per day and more, drilling engineers continue to look for cost-effective alternatives.

This area of the site is restricted. In order to gain access, please either Log In, or subscribe to World Oil.

Two options are available to you for creating an account.

1. Get a Free Trial Subscription to World Oil Magazine and gain immediate access to select content on World Oil Online.

Start a Free Trial Subscription and gain immediate access to the complete current issue of World Oil Magazine. Plus, you’ll receive 3 upcoming issues of World Oil Magazine in print or digital format.* You also receive access to the Energy Events Calendar, Industry Statistics and WO Wire’s news and industry coverage.

Free Trial

2. Purchase a subscription to World Oil magazine and gain immediate and complete access to World Oil Online. As a Total Access subscriber you will have access to all areas of the site available to registered users and free subscribers as well as having access to such premium content areas as:

  • The Archives section containing over ten years of complete magazine archives,
  • The WO DataHub's engineering tables and directories,
  • The World Oil annual forecasts, including past predictions,
  • Select World Oil technical handbooks,
  • And much, much more!


Physical copies of this content may be available for purchase. Visit the Reprints & Back Issues section.

If you are already a paid subscriber and do not have access, please email



Engineering Data Tables

World Oil's specialized upstream Engineering Data Tables featuring the Drill Bit Classifier, Tubing Tables and more. Get Total Access today.


2013 Fracturing Technology

2013 Fracturing Technology