Getting gas out of the ground
ASPEN – It’s shortly after 6 a.m. on a cold December day in the Mamm Creek gas field south of Rifle. The pre-dawn gloom is broken by a handful of well-lit drilling rigs that poke up from the rolling terrain like turrets on a sprawling castle.Six diesel engines produce a loud, hypnotic hum at a rig operated by a company called Caza, which subcontracts to EnCana Oil and Gas USA, one of the biggest natural gas producers in Garfield County. The ghostly hue of fluorescent lights floods the main floor where the rig’s drill bit bores into the earth through a hole surrounded by thick steel grating of the platform.Suddenly a horn blares above the throbbing diesels and three workers converge on the rig floor from different directions. The time has come for the crew to stop the drilling of a well more than one mile underground and slip in a new 30-foot section of pipe so the drill bit can continue eating into the sandstone.Without a word, they whip into action, grab two gigantic pipe wrenches – called tongs – that are anchored by thick metal cable. The lead rig hand, known as the driller, hits a lever that stops the spinning of a 40-foot hexagonal metal piece called a kelly, which hangs down in the middle of the towering rig and spins the drill far underground.The floorhands – brothers Chris and Derek Thompson, and their cousin Benjamin Garner – swing the heavy metal tongs into place, clamp them and pull different directions to break the connection between the kelly and drill pipe. Then they wrap chains around one of several lengths of 30-foot pipe cached nearby and step back as the driller pulls a lever that hoists the pipe into the air. Nobody misses a beat.It’s a typical day on a drilling rig in western Colorado, a region in the middle of a natural gas boom that’s brought hundreds of roughnecks from around the West to toil at their tasks.While the Thompsons and Garner are toiling, murky water and drilling mud that was being pumped into the well gurgles out and flows across the metal grating where they are working. It makes the already dangerous work even more treacherous.The tan Carhartt overalls of the Thompsons are covered with grease, machine oil and dirt. Garner’s jeans are so stained they can no longer be called blue. Their collars are pulled tight around their necks to fend off the early morning chill that stings cheeks and other exposed skin in just a few seconds. The thermometer reads in the teens before the first morning sun bathes the rig.The crew wrestles the drill pipe into position as it dangles from a giant hook in the derrick, the part of the rig that looks like a windmill frame. They swab grease onto the threads and use the tongs again to connect the pipe and kelly. The team works quietly and efficiently – a requirement on a rig.”The old saying is you only go as fast as your slowest hand,” said Richard Eberspecher, a drilling superintendent who, as a consultant, oversees the drilling rigs that EnCana operates in the Mamm Creek Field. There were 14 drilling rigs in the field last year. EnCana reduced the number to 10 this year, in large part to answer critics and residents of the area who claim there is too much traffic and disruptive activity.
Dull is good on a rigOnce the new pipe section is in place, drilling resumes and the floorhands go back to their jobs. Derek, who happens to work in a position known as derrick man, makes sure the proper levels of a clay called bentonite, fresh water and chemicals are mixed to create a drilling mud that is pumped into and out of the well as both a lubricant and substance to bring cuttings to the surface.Chris, the motorhand, oversees maintenance of the diesel engines that are the heart of the rig by supplying power.Garner works as the “worm,” or “in the worm’s corner,” nicknames signifying he is the low man on the totem pole. He cleans equipment and does whatever he is told.Connecting a section of pipe, a process that takes less than 15 minutes, breaks the monotony of the 12-hour shift on the drilling rigs. “The job’s real redundant,” says driller Scott Stiffler.The drilling rig has bored down 7,000 feet over the course of 15 days. Its target depth is 8,100 feet. EnCana taps into sand pockets that are trapped in surrounding shale starting at 3,500 feet underground and going much deeper.Three new wells will be drilled from this pad and an old well, which had been capped after methane gas was tapped years ago, will be drilled again to reach gas trapped at greater depths.Some of the wells will be drilled straight down. In many other cases, EnCana will use directional drilling – burrowing in at a slight angle – to tap a wider variety of pockets where natural gas is trapped while minimizing surface disturbance.Directional drilling adds about $100,000 to the cost of drilling a well, according to Walter Lowry, EnCana’s director of community and industry relations. Nevertheless, the company uses that technique about 95 percent of the time, he says.The rate of drilling depends on the type of rock encountered. At this particular Caza rig at this particular time it is slow going at only 12 feet an hour, rig manager James Barclay says with a disgusted look. The average is 21 feet per hour.The rig manager, whose position is also known as toolpusher, yearns to see steady progress without any troubles. Barclay, who lives on a trailer at the site for the 14-day shift before getting a week off, can tell just by the sound of the rig how smoothly the operation is going.”I want it dull,” he says with a smile. “I want it so boring that I can’t take it no more.”Barclay’s rig will spend about 80 days at this pad to drill the four wells, then move elsewhere in the field. Up to 12 wells are being drilled from some pads, according to Eberspecher.275 new holes a year
Jobs in the gas field are specialized. Different crews are responsible for drilling the wells, installing casing in the wells once the drilling is finished, hydraulic fracturing of the rock where the gas is contained and finishing the well for production.When Barclay’s crew finishes, the drill pipe is replaced by steel casing pipe, which is enclosed by concrete. Then the drilling rig is disassembled and moved to a new location.EnCana, the largest producer in Garfield County, employs about 15 workers at its Rifle field office. It subcontracts with several other companies – which employ up to 500 workers on any given day and a total of about 1,000 – to get the gas out of the ground.EnCana embarked on large-scale operations in the prolific Mamm Creek Field three years ago, Lowry said, and it now has 775 wells in the Divide Creek, Hunters Mesa and Grass Mesa sections of the field. Lowry said about 275 wells were drilled in 2004 and about as many are expected this year.In just four years, as prices have increased, EnCana’s production has skyrocketed from 25 million cubic feet per day to roughly 240 million cubic feet per day this year in its fields in Garfield County. That is equal to almost 71 percent of Colorado’s total residential demand for natural gas in all of 2003. Even with the high reserves of gas in the Mamm Creek Field, drilling wouldn’t be economically feasible without technological advances over the last decade and skyrocketing prices for gas.The gas is difficult to recover because of the rock south of Rifle isn’t permeable – gas doesn’t flow easily through the shale and other rock to the well bores. In the oil and gas industry, the underground formations like those found in the Mamm Creek Field are called “tight sands.””Technology has allowed us to get gas out of a place like this,” Lowry said. “Without this technology we wouldn’t be here.”‘Fracing’ makes drilling feasibleTo recover the gas, EnCana forces water and sand into the cased wells at high pressure to fracture rock. In the lingo of the gas fields, it’s called “fracing,” pronounced fracking.Once the wells are drilled and encased, a different crew – the fracking crew – takes over the site. Perforating guns are inserted into the wells. Specially shaped explosive charges are strategically placed so that when explosions occur, the blasts riddle the metal casing that lines the underground wells, the cement around that metal casing and the rock that surrounds it for a few feet with the bullet-sized holes.After the holes are made, a mixture of chemicals, water and perfectly round, uniform-sized grains of sand, imported from the Great Lakes region, is forced down into the well at high pressure, as much as 5,000 pounds per square foot at the surface. That mixture shoots out of the bullet holes and creates numerous fractures over narrow intervals of surrounding rock.Mark Balderston, a consultant who supervises fracing for EnCana, says the process is like taking an old, faint game trail in the forest and transforming it into a superhighway.When the water is pumped out of the wells and surrounding areas, the sand is left behind to wedge the tiny fractures open, allowing the gas to flow into the well bore.
Balderston said about one million gallons each of water and sand are used per well in the process.”We recycle close to 100 percent of the water we use and produce,” Lowry says. Critics worry that some of the water, chemicals and gas leech into their wells and groundwater supplies.In contrast to the labor-intensive drilling process, the fracing operation is handled by computer operators rather than by roughnecks. Semi-trucks and computers are the tools of choice for the 20-person crew rather than tongs and drills.Eight semis hauled materials to a site on Hunter’s Mesa where Balderston was overseeing a fracing operation one day last month. In the middle of the site was a souped-up mobile home that on the inside looked more like a NASA command center than a work shack in a gas field in rural Colorado. Rows of computers with operators monitored everything from the mixing of chemicals, water and sand to its high-pressure trip down the wells.Without that process, the wells in Mamm Creek would produce about 50,000 cubic feet of natural gas per day, according to Balderston. With the fracing, that jumps up to two million cubic feet per day, he said.Nice return on investmentOnce the fracing crew’s work is done, a final crew – called a workover or completion crew – prepares the wells for production. That crew drills through plugs in the wells, which were used during the fracing process to allow the work to be done in stages.The workover crews also flush a new well of sand using a series of tanks called sand traps.When that process is completed, the site is reclaimed. Pads are about four acres on average. After reclamation, less than a one-acre site remains for production equipment, according to Lowry. Often all that remains are wellheads with an assemblage of valves, gauges and pipes that are called Christmas trees due to their appearance. Other reclaimed sites could include storage tanks and separators.Each well costs about $1.1 million to drill and complete, substantially more than a conventional well because of the fracing and directional drilling. But EnCana isn’t complaining – the wells provide an excellent return on investment. Each well will produce natural gas for 20 to 30 years depending on demand and prices.The Mamm Creek gas field has proved so prolific that EnCana is now going back and hitting the spots between the initial wells, a process called “infill drilling.” The underground spacing between wells will be reduced from between 160 and 40 acres, which exists now, to 20 acres.”We haven’t drilled a dry hole here since we took over this field in 1998,” Lowry says. “Some holes are significantly better than others.”Vail, Colorado