Jayson Walmsley, President and CEO
The Horn River Basin has attracted attention as one of the latest resource plays to emerge in the Western Canadian Sedimentary Basin. Following in the footsteps of such shale gas plays as the Barnett, Antrim and Caney Shales, the Horn River discovery led to a surge in land sales in remote northeastern British Columbia. Mineral rights for more than a million acres were secured by oil and gas companies in the last few years.
While the presence of gas in this stratigraphic unit was known for decades, it took recent technological advances to make this play economical. In addition to the universal shale development-enabling technologies—horizontal drilling and multistage fracturing—multi-well pad drilling minimizes the environmental impact, and invert mud keeps open holes under control.
Large quantities of gas are present in various horizons of the Horn River Formation. Commercial quantities of gas can be extracted from the Muskwa Shale, Otterpark member or Evie member. The thickness of the shale stack makes this target an ideal candidate for multistage fracturing. Reserve estimates vary from 100 to 600 Tcf, of which 10–20% is recoverable with current technology.
Remote geosteering. Real-time data relay from the wellsite has become very robust and reliable in the past few years. Geologists can acquire continuous drilling and MWD parameters to decide the optimal steering direction in real time at any distance, and decisions can be instantly relayed to directional drillers. Geologists with extensive wellsite experience are key to the efficiency of geosteering operations, whether they are located at the wellsite or remotely.
Cuttings samples can be collected at the wellsite using semi-automated sample catching systems that require minimal supervision; they can be prepared and described at a later time in a lab. Alternatively, samples can be caught and prepared by a less skilled mud-logger technician in the field. The mud-logger can also maintain and operate a mud gas detector and take digital images of the cuttings, which can be transmitted in real time to remote geosteering personnel. For in-depth analyses, critical samples can be collected and preserved in geo-jars and gas samples can be harvested in iso-tubes and preserved for subsequent analyses in a specialized lab.
Similar technology has been used effectively in offshore operations for many years. The North American market is just beginning to embrace this approach. In recent months, our company has talked with many operators who are interested in applying this system to their large resource plays. With the industry shifting to unconventional plays, we expect to see more operators embrace this model, augmenting the role traditionally held by the wellsite geologist.
Applying it in the Horn River. Most conventional plays are not suitable for remote geosteering, due to the fact that the best borehole follows the best quality reservoir, and cuttings sample observation is crucial in determining the optimal wellpath. Large resource plays like the Horn River, however, are prime candidates for this method, thanks to good well control and in-depth knowledge of reservoir characteristics. In most cases, a single stratigraphic pilot well, cored through the zone of interest, will provide both the needed well control and reservoir knowledge required for a large multiple horizontal well pad.
MWD tools, specifically gamma ray, are required to effectively drill Horn River horizontals. Correlation of gamma markers to offset wells is a critical tool used to determine the landing point of these horizontal wells. Sample descriptions are of little value to this process, but continuous supervision of MWD and drilling parameters, and communication with directional drilling personnel, are the key for optimal landing.
As for the horizontal section, the hydraulic fracturing completion creates large permeable conduits around the wellbore. This minimizes the need for the wellbore to be placed in the best possible reservoir; the hole can be drilled at some distance from the best natural porosity and still tap the entire hydrocarbon potential. Constant supervision of MWD and drilling parameters is sufficient to choose the optimal drill path in such wells.
Steering based on cuttings samples is ineffective in this kind of play; high penetration rates produce contaminated samples, and the lag time delays the process further. Lithology within a homogeneous formation gives little to no information regarding the position of the wellbore within the uniform rock unit.
Why remote geosteering? Having a focused group of geologists following a project around the clock allows more accurate data acquisition. Remote geosteering personnel are not distracted by other tasks that typically must be carried out by wellsite geologists, such as time-consuming sample preparation. This allows them to focus on the task at hand. Having personnel who are continually aware of exact rig operations on a 24-hour basis results in a more detailed and faster flow of information, facilitating timely and accurate decision making.
Adding to these advantages, remote geosteering means fewer people needed at the wellsite, which saves transportation and accommodation costs and reduces exposure to hazards.
Big picture. Despite the large recoverable gas reserves of the Horn River play, operators in the area face many obstacles—one of the biggest being the need to be cost-competitive with other shale gas plays much closer to market. The logistics of drilling in the remote northern reaches of British Columbia only add to this pressure. Although the use of a remote geosteering approach will reduce geological operation costs, it represents a minimal savings to the overall cost to drill and complete a Horn River well. The cost of using a conventional team of wellsite geologists usually represents less than 1% of the total authorization for expenditure. In the long term, there still remains much work to do to make this play economic and sustainable. 
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THE AUTHORS
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Jayson Walmsley earned a BSc degree in geology at the University of Alberta in 1992 and immediately began work as a wellsite geologist. He has worked on more than 350 wells in Western Canada, including challenging underbalanced gas horizontals, oil sands coring programs and carbonate horizontals. Mr. Walmsley founded Chinook Consulting in 2002 and has managed its growth to a current roster of 40 wellsite and operations geologists.
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