Light, durable mats extend drilling season in Canada

July 28, 2003
Light, durable mats have extended the drilling season in the Western Canadian sedimentary basin (WCSC), as shown by Apache Canada Ltd.'s program in Zama field in Alberta.

Light, durable mats have extended the drilling season in the Western Canadian sedimentary basin (WCSC), as shown by Apache Canada Ltd.'s program in Zama field in Alberta.

Newpark Resources Inc., manufactures one such mat, the DURA-BASE, which it describes as an interlocking, high-density polyethylene (HDPE) composite mat system, introduced to the market about 3 years ago.

Western Canada

The industry for some time has known and understood the geology of gas prospects in Western Canada, but difficult access conditions, a narrow 3-4 month drilling window, and increasing environmental concerns have slowed exploration drilling programs.

A well site at Apache's Zima field shows the effects of the Spring thaw on the muskeg (Fig. 1). Photo courtesy of Apache Canada Ltd.
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Wells in this region range from 300 to 6,000 m deep and drilling times vary from a few days for shallow wells to several weeks for a deep well or complex side-track.

Extension of the drilling season would accelerate development of natural gas resources while gas demand is high, thereby improving the overall return on a project's investment. But Newpark says the unstable ground conditions complicate safely gaining access to and conducting well completion and pipeline hookup operations (Fig. 1).

The company says the problem is the Canadian muskeg a soft, unstable water-saturated peat. The company attributes this instability to the extreme temperature fluctuations in the area from –40º F. in winter to 100º F. in mid-summer that cause the soil, which is frozen most of the winter, to soften to a soup-like consistency with warmer weather in spring and summer.

Newpark says the muskeg can bog down equipment in half a meter of mud. In areas where the muskeg is 5 m or more deep, the muskeg potentially can submerge large equipment, thus creating safety issues, delays, and other problems. And, the company adds that many field operators have testified to seeing entire pieces of machinery disappear, engulfed by deep muskeg.

Mats, covering a location, help extend the drilling season in Western Canada (Fig. 2). Photo courtesy of Apache Canada Ltd.
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Besides these logistical difficulties, Newpark says the muskeg regions are regulated heavily in order to protect the large and varied wildlife population and much of the natural vegetation.

To extend the drilling season, some operators place mats on the muskeg (Fig. 2).

Roads

Drilling projects in the WCSB may require an ice road in winter or other temporary road material for drilling throughout the year.

Newpark says once the winter freeze occurs, usually around mid-December, operators can typically build in 2 weeks an ice road that extends about 40 km into the lease. It says that ice roads, created simply by water sprayed from a truck and continuously packed by passage of other vehicles, are the most economical way for gaining access over muskeg during winter.

A road without mats leads to one of Apache's Zima field drill sites (Fig. 3). Photo courtesy of Apache Canada Ltd.
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But around mid-March, once the ice roads thaw and the muskeg liquefies, the company says operators are banned from the roads and have to be off location unless temporary roads are available.

Newpark says operators have used road matting or clay and gravel fill for improving access roads in muskeg or soft-soil conditions during the spring and summer. Although fill materials are plentiful and cheap, it says road development is justified only when sufficient hydrocarbons are known to be present and productive.

It adds that matted roads, while initially more expensive, are temporary and quickly installed and removed.

These roads, according to the company, provide the load-bearing strength to overcome the problem of oversaturated soil, and the mats can be reused on subsequent projects in the same area until the operator meets its drilling and producing objectives (Figs. 3 and 4).

Newpark says that after an operator establishes production, it typically will build and maintain permanent access roads for long-term use. These roads are built from clay and gravel and typically have a poor substructure that requires continuous maintenance, according to Newpark.

Mats placed on the road to Apache's drill site provide the load-bearing strength to overcome the problem of oversaturated soil (Fig. 4). Photo courtesy of Apache Canada Ltd.
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It adds that the roads are susceptible to heavy rains that can make them impassable to trucks and wheeled vehicles, although emergency fill material or temporary reinforcement with matting can bolster a softening roadway.

In extreme cases, however, it says heavy equipment is required to tow transport trucks through the mud to the drilling location and back, adding both to the operating costs and vehicle wear and tear.

Newpark says temporary roads that use matting are particularly effective in areas where wells are closely spaced and soil conditions are unstable. It cites such locations as Grand Prairie, High Level, Fort St. John, Fort Nelson, and Fort McMurray, where muskeg covers 25% to 65% of the region, as having projects that have benefited from temporary mat roads during spring break-up and to facilitate summer drilling.

It says some operators have purchased their own mats to reap the benefits of rapid, frequent deployment to locations that had previously been out of reach during the warm months.

Apache application

Apache is an operator that has studied the advantages of owning a mat inventory for year round use. "Because of the access challenges, the tight drilling window, and strict ecological regulations, it would be impossible to bring in the heavy equipment needed for drilling and exploration without matting," explains John Laidlaw, Apache's drilling logistics supervisor.

"We have a limited opportunity in which to operate; the mats allow us to extend that window. In some cases, there's no way to meet these deadlines other than with the use of matting," Laidlaw continued. "Look at it this way, if we didn't try to maximize the most efficient means of site and road preparation, we could spend most of our time getting to the site and not drilling."

Apache Canada's program in Zama field highlights the challenges of drilling in this region. Apache acquired the Zama field from Phillips Petroleum Co. in December 2000 as part of a program to develop and exploit formations in Northwest Alberta's muskeg region and currently has several rigs running the field.

With the winter drilling season as short as 3 months, Apache says it uses matting products that vary from wood-based to composite plastic units engineered for this application. Late in 2000, Apache says it invested in a significant number of DURA-BASE mats that are about half the weight of a similar wooden mat surface, thus making frequent transport more efficient

"Other matting products might have worked, but the longevity of DURA-BASE and the significant savings we achieve in trucking costs make DURA-BASE an economically viable solution," said Laidlaw.

"With composite mats we can increase our rate of return (ROR) by 20% in this area – which makes the matting worthwhile. The mats have certainly added more flexibility to our drilling program," he said, adding:

"With the addition of DURA-BASE to the operator's inventory, the fixed cost of matting could be amortized over a few years, with the mats paying for themselves after only a few projects."

Mating increases the risk you can take, continues Laidlaw; "It allows us to get into locations earlier and stay later because it provides access over the softening muskeg at a time when other operators simply shut down. In Zama, we are able to use them to the greatest effect."