Summary
The precise placement of well pairs is one of the most-crucial factors in
the successful execution of a steam-assisted-gravity-drainage (SAGD) drilling
program. A SAGD drilling program includes placing the producer well relative to
the reservoir boundaries and twinning the producer with the injector well
accurately. Delivering on these high expectations in unconsolidated formations
(e.g., the McMurray oil sands in Canada) requires a strong focus on
technological innovation.
A common practice in drilling SAGD wells in northeast Alberta is to drill
lateral SAGD pairs with conventional, steerable mud motors and
logging-while-drilling (LWD) resistivity measurements. Although this
combination has delivered success, certain limitations exist in terms of
wellbore quality and placement. At a demonstration project by a major oil
company, several industry firsts were implemented successfully, including a
combination of the newest and most-cutting-edge directional, measurement, and
LWD technology.
The keystone of these industry firsts was the application of a
soft-formation-modified, point-the-bit rotary-steerable system (RSS) used on 20
horizontal wells. Combined with an ultradeep azimuthal resistivity sensor, the
RSS provided precise geosteering along the bottombed boundary in the producer
wells, resulting in improved reservoir capture and characterization. More
on-bottom time enabled more-efficient drilling and reduced well costs
significantly. Highly smooth liner runs reflected the lack of tortuosity in the
wellbore, made possible by the rotary bottomhole assembly (BHA). Improved
directional control made uniform well separation possible between lateral
pairs, thereby reducing the risk of hot spots and short circuiting during SAGD
operations. The use of an even-walled power section above the RSS increased the
bit rev/min for improved BHA responsiveness while minimizing casing and pipe
wear. Overall, the results and lessons learned from the demonstration of these
new techniques provide a clear indication of the progressive future of
directional drilling in SAGD.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
13 November 2010
- Meeting paper published:
20 October 2010
- Revised manuscript received:
21 December 2011
- Manuscript approved:
22 December 2011
- Published online:
12 March 2012
- Version of record:
14 March 2012
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