Tube & Pipe
Monday | 24 May, 2010 | 7:06 am

Strength under pressure

By John Loos

May 2010 - Some of us wait a lifetime to realize our full potential. The Haynesville Shale, which is several miles beneath the U.S. Gulf Coast, has been waiting 150 million years.

Geologists have known for some time that the black, organic-rich shale, which was deposited in the Upper Jurassic period, contains large amounts of natural gas. But because of its low permeability, the Haynesville Shale has long been considered a gas source rock instead of an actual gas reservoir.

Now, thanks to enhanced directional drilling techniques and advanced technologies, including high-performance premium pipe connections from TMK Ipsco, Downers Grove, Ill., the Haynesville Shale is beginning to achieve its potential as a significant source of natural gas.

TMK Ipsco specializes in welded and seamless pipe and premium connections for the oil and gas industry. Its Ultra premium connections are unique threading configurations at the end of pipes used in oil and gas applications, and they’ve been instrumental in the surge of directional drilling operations in the United States.

The connections were first envisioned nearly 20 years ago when an engineer sought to design the perfect thread, which is defined as a connection with the same outer diameter and inner diameter as the pipe body with the same strength parameters, tension compression, pressure and torque performance as the pipe. This research led to an innovative square-shape design and, eventually, the birth of TMK Ipsco’s line of Ultra premium connections in 2005. The connections are able to withstand the extreme conditions and the high torque and compression requirements associated with directional drilling.

"The connections are stronger in all the different parameters than most of the other connections in the flush and semi-flush world," says Ed Banker, director of technical services for TMK Ipsco."And the reasons people use these small-diameter connections are: No. 1, they’re trying to get the largest piece of pipe they can down a given wellbore, and No. 2, when you drill the long horizontals, it’s difficult if you have couplings in there. It’ll tend to increase your drag, so the slim-line integral connections are better suited for that purpose."

The advent of the Ultra premium connections was well-timed. By the end of 2009, horizontal and directional rigs accounted for 76 percent of all natural gas rigs in the United States.

Drill, baby, drill
Directional drilling allows companies to tap the possibilities of shale plays by increasing the effective length of the wellbore in the productive interval.

Although engineers have experimented with horizontal drilling technology since the 1970s, it didn’t come into prominence until late in the 1990s, when engineers in Texas’ Barnett Shale began horizontally drilling their well strings in an effort to increase their exposure to new shale layers.

Well curvatures soon became more severe, and fracturing pressures increased dramatically--n the Haynesville Shale, they can be upward of 15,000 pounds per square inch. This meant traditional API pipe connections were no longer able to handle these stresses.

Comstock Resources Inc., Frisco, Texas, a $4 billion independent energy company engaged in oil and gas acquisitions, exploration and development, has drilled roughly 50 wells in the Haynesville Shale and has seen the advantages of the Ultra premium connections in its directional drilling operations.

"We install a 16-inch conductor down to about 80 feet," says Bryan Stringer, senior drilling engineer for Comstock Resources. "Then we grout that in with cement. Then we move in a drilling rig and drill down to about 1,900 feet. We set 103/4-inch surface casings to protect fresh water and also provide a high enough fracture gradient so we can drill to the next level.

"Then, we drill to about 10,500 feet vertically and set 75/8-inch casings and cement that in," he continues. "Next, we drill that out and continue drilling vertically to about 10,800 feet. At this point, we initiate the curve horizontal by the time we get to about 11,300 feet, depending on the area we are in. We drill over 5,000 feet laterally, so that puts the total depth of the well at about 16,500 to 17,000 feet. And we’re still at 11,300 feet on a true vertical basis."

At this point, Stringer says,"Comstock is drilling a 63/4-inch hole. So the problem is you’ve got this well drilled, and you need to be able to run production casing to bottom. This is going to be the casing that flows the gas to the surface."

At first, Comstock used a 5.5-inch flush joint finished off with a 5.5-inch, 23-pound-per-foot-long threads and coupling (LTC), which didn’t have a particularly high torque rating. This proved problematic when running it through the curve from vertical to horizontal, Stringer points out.

"What we found was that it’s very tight running that 5.5-inch casing in a 63/4-inch hole," Stringer says. "There’s not very much annular clearance. One of our wells took 72 hours from the time we started running production casing until we got it on bottom. The casing running company actually brought barbecue pits, tents and satellite TV dishes out to the well site because when they came out there, they knew they might be there for three days."

Unable to rotate the LTC couplings at high torque, Comstock decided to use a 5.5-inch, 23-pound-per-foot Ultra semi-flush connection in the vertical section of the hole.

The result? Instead of taking 72 hours to run pipe to bottom, Comstock is now able to run it in 12 to 15 hours.

"We couldn’t find any threaded and coupled connection that was cheaper than the Ultra semi-flush for running in the vertical portion of the well," says Stringer. "We know that it’s got a high torque rating, and we can get everything from one supplier. So that’s how we came up with our design. Basically, the reason we use the Ultra semi-flush is we’ve got good availability, we’ve got good price structure and we’re familiar with it because we have run it in the past."

Slimming costs
Considering Comstock’s wells cost more than $7.5 million to drill and complete, and the company drills a new one roughly every 45 days, ensuring they’re productive and that the pipe and pipe connections are of the highest quality is essential for success.

In one instance, a Comstock casing job was halted when pipe stalled about 1,500 feet from bottom with the original design. TMK Ipsco’s Ultra semi-flush connections were used on the next well and allowed Comstock to reach bottom and make subsequent wells more productive.

"We’re happy with the connection; it’s saving us a lot of money and it’s given us a more reliable casing running process," says Stringer. "We have a better chance of being able to rotate the pipe to bottom with the higher torque connections, and we haven’t had any connection failures."

Ultra premium connections aren’t just allowing companies to tap the potential of natural gas sources like the Haynesville Shale. They’re also allowing TMK Ipsco to fully realize its potential as a supplier of high-quality connections for the oil and gas industry.

Consider this: In 2009, U.S. rig counts reached their lowest levels in six years, and shipments of oil country pipe dropped 62 percent. However, in that same time frame, sales of the Ultra premium connections increased 22 percent. Since 2007, they’ve increased 54 percent, allowing the company to open a third production facility in Brookfield, Ohio, to help serve customers in the neighboring Marcellus Shale.

"We see future use of the connection in other applications simply because the shale plays require a strong connection that has a small OD and a strength approaching that of the pipe body," says Banker. "There are a lot of other applications that use the same combination of slim OD and high strength, so our connections will be very useful. As wells around the world get deeper and hotter and become more difficult, the concept of using slim-OD, high-strength connections will continue to grow in the future." MM

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