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Cement plays vital role in drilling

Profile image for By Beth Francesco / For the Denton Record-Chronicle
By Beth Francesco / For the Denton Record-Chronicle

Dangling about 125 feet above the ground and swinging in stiff winds, a 90-foot string of pipe bangs against the cold, metal drilling rig, slipping from the tool pushers below. The clanging is startling, but the roughnecks atop a three-story-high platform manage to gather the monstrous pipe and maneuver it into place.

On the dusty gravel pad below, four crewmen clad in red coveralls lean against a Halliburton truck, waiting. Some gnaw gum. Some spit. Some wipe dust from their faces as they prepare for their critical step: setting the thin layer of cement that protects aquifers from the surge of dirty salt water and other fluids that will come barreling back to the surface from thousands of feet below - if the Barnett Shale is properly fractured. ALSO ONLINE

  Texas Railroad Commission inspections and orders of Lucky Oil & Gas


With 14,000 gas wells and a maze of pipelines and production equipment, the country's need for a cleaner fuel conflicts with the fast-growing cities and suburbs in 23 North Texas counties above the Barnett Shale.

• SUNDAY: In the small town of Dish, the proliferation of gas industry equipment is creating an atmosphere of concern.

•  Atmosphere of concern

•  Industry fueling region's transformation

•  Dawn Cobb: Citizens of the Shale

• MONDAY: Flower Mound, recognized for its "SmartGrowth" planning, now grapples with the changes of a budding gas industry.

•  Defending the Mound

• TODAY: Water, a precious resource in a high-growth state, could be under threat by a process known as hydraulic fracturing that is used to extract gas from deep underground.

•  Just below the surface

• TODAY: As other states question hydraulic fracturing, Texas continues the practice amid claims the state is ill-equipped to monitor it closely. Also: A look at cement's role in gas drilling.

•  Hard work ahead

•  Cement plays vital role in drilling

• THURSDAY: Six million people live above some 27 trillion cubic feet of gas in the Barnett Shale, now at the center of attention among policy-makers looking to balance the industry and North Texas lifestyles. Also: A look at a practice known as "landfarming."

Clang, clang. More dust. More wind. It may be a new, high-tech process for natural gas production, but the old safeguard is the same - and setting 31,000 pounds of pipe can't be rushed. Each piece is connected by threads and heads that have to screw together perfectly. The vacuum seal formed by the connection means the difference between a good string of pipe and a bad one. And a bad string of pipe means toxic chemicals and salt water used in fracturing the gas-rich Barnett Shale might leak out, contaminating underground aquifers that supply irrigation and drinking water to North Texas.

So work must proceed carefully with Devon Energy's gas well in Wise County - one of seven running for the company in mid-November. According to records and interviews with several gas drilling experts in Texas, a lot can go wrong in cementing a gas well, and it often does. Anything from inclement weather or faulty equipment to a botched mixture of cement and water can produce dire environmental consequences and human health risks.

"The most important thing that probably happens in the history of a well is how this form application for drilling is filled out and how the circumstances that you could run into are taken care of," says Dale Henry, a longtime petroleum engineer and master cementer. "It cannot be a rubber-stamp deal."

An hour and a half pass. The last of the surface casing stands in place, its head poking several feet above the base of the drilling platform. The men in red coveralls mill about, kicking up dust with their boots. They are anxious to mix and pour the cement and finish this part of the job - the start of a long process of stop-and-start mixing, pouring and waiting. Garrett Jackson, Devon's Bridgeport drilling operations supervisor, checks his watch, but he's in no hurry. Moving slowly and methodically is the only way to safely work toward fracking the hard rock of the Barnett Shale, he says. Taking the time to get the surface casing correct is time - and money - well spent.

Devon's on-site manager, Roy Darden, gathers the cement and other crews for a safety check before the gray stuff will course through and up around the just-laid pipe: Who's monitoring the materials truck? Who's testing the batch of cement, calcium carbonate and water? Who's in charge of seeing to it that the watery concoction winds its way up and around the drill pipe properly? Everyone gets an assignment. Darden orders his crew to stay alert for any glitches. One glitch, Darden shouts against 36 mph winds, and the job shuts down - immediately.

Minutes later, the safety meeting is over. The mixing truck whirs and stirs a precisely measured mixture of water, cement and calcium carbonate, which speeds the cement's cure. Daryl Scofield and another worker perch atop the mixing truck. While he pilots the truck, monitoring the electronic cockpit that measures, second by second, the density of the mix and the pressure it is under, his co-worker tests the material by hand - "like they did in the old days," Scofield says when the job is done.

The cement mixture flows up to the platform via three stories of pipe to the newly laid casing, which is outfitted with a pressurized cement intake head. The cement works its way down through the casing and up around its exterior, filling the area between the pipe and the earth that a drill bit chewed through the night before. A failure to fill even a tiny crevice with the mixture means the well could succumb to "washout" - cakes of mud chewed away in the drilling process, leaving gaps that suck away the water in the cement. The mixture used in this job, Jackson says, contained an extra 30 to 50 barrels of cement - up to 2,100 gallons - to ensure a solid seal.

Halfway through the job, Scofield's crew reduces the amount of water in the cement from 14.5 gallons per sack of cement to 9 so that the casing closer to the surface sets faster, keeping the wet stuff on pace with the four-hour basic curing time all cement - above or below ground - requires.

On any rig, time is money. On this rig, it's about $2,000 an hour for equipment and personnel.

An hour after the job starts, another waiting game begins. Darden, the on-site manager, and an inspector for the Texas Railroad Commission hover over the reserve pits about 30 feet from the rig, where excess cement is supposed to flow when it returns to the surface. That's how the crew knows the job is done, and how the Railroad Commission knows the law has been followed.

At first, there's just a trickle of muddy water. Then the brew darkens, with cement flowing back at a good rate, indicating the pipe is encased and cementing can cease. As the flow-back cement dumps into the reserve pit, crews mix in a 94-pound sack of sugar - the same that sweetens morning coffee or gets spun into cotton candy - to keep it from hardening as it is trucked away. Darden and the inspector watch intently as the cement pours out of the hole and slows to a trickle.

"Yo," Darden shouts, pumping his fist in the air to signal that this part of the well - the surface casing - is complete, and the wait for the cement to harden begins. After the cement hardens, more drilling will take place, more pipe laid, string by string, until it reaches a curve several hundred feet below and stretches 11,500 feet horizontally, under farms and homes. The well's twin is about 100 feet away, laid only weeks earlier using the same Devon rig.

To most people, cement is so ubiquitous - the common ingredient in modern concrete structures - that few may think of cement as high-tech. Yet, in its pure form, cement is critical to well drilling and gas production.

Some experts contend that the complex mixing, pouring and curing of cement under invisible, high-pressure conditions hundreds of feet below the surface of the Earth is a leading culprit in environmental catastrophes associated with oil and gas drilling - on land and offshore. But myriad problems associated with "cementing failures" have remained out of public view - until now.

The world woke up to the hazards associated with botched cement jobs after a BP-leased platform in the Gulf of Mexico exploded April 20, killing 11 rig workers and leaking millions of gallons of oil into the Gulf of Mexico over several months. The National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling blamed the explosion on a faulty cement job involving unreported stability tests and ill-prepared materials. "Cementing wells is a complex endeavor, and industry experts inform us that cementing failures are not uncommon even in the best of circumstances," the commission reported.

The report goes on to say: "Because it may be anticipated that a particular cement job may be faulty, the oil industry has developed tests, such as the negative pressure test and cement evaluation logs, to identify cementing failures. It has also developed methods to remedy deficient cement jobs."

None of the more than 14,400 gas wells drilled in the Barnett Shale in North Texas is exactly like another.

The varying amount of experience of the crews that do the work, the rig's design and the proprietary fracking fluids all make each well vary.

What they have in common is a dependence on cement to prevent leaks, including leaks of the chemical-laden fluids as they are pumped underground, under thousands of pounds of pressure, to break the rock and release the gas. As the BP spill illustrates, any cement job can turn into a disaster due to human error or the unknowns below.

At active and inactive drilling sites across the state, the Railroad Commission conducts numerous inspections involving cement, which is used in nearly every step of the well's setup. But inspection records, obtained in an open-records request, reveal that attempts by the commission to address hazards associated with reckless drilling practices aren't always successful.

Through its drilling permits, the Railroad Commission requires operators to spell out their intentions before any pipe is sunk. The agency wants to know how deep into the earth the operator plans to drill, how much gas it intends to extract and what methods it intends to use to extract it, such as conventional or horizontal drilling.

Henry, the longtime petroleum engineer and master cementer, says the place to put a neon marker on the permit application is on line 21 - where the agency seeks the sort of information it needs to assess whether the driller is prepared to take all the steps necessary in the drilling, fracking and cementing processes to protect against a breach. The details of a job can vary as widely as a fingerprint, with variables involving everything from the size of the open hole and pipe to the quality of the cement the operator chooses.

In Comanche County, located on the perimeter of the Barnett Shale area, landowner Roy Johnson knew something wasn't right with a rusty wellhead on his property, state records show. The customarily lush coastal Bermuda grass surrounding the wellhead had dried up, and tiny white crystals littered the dirt left behind.

The sight of glistening crystals around the wellhead spurred Johnson to call the Railroad Commission in 2008 and ask for an investigation. Inspectors discovered that the 30-year-old well was leaking salt water.

One year later, the dead zone around the well had tripled to 56 square feet. How deep the salt water had seeped into the ground was anyone's guess. Two years and 23 inspections later - each monthly inspection revealed breached cement at the top of the well had not been addressed - the agency ordered the inactive well plugged for a second time, in March 2010.

Lucky Oil and Gas Co. was fined $13,750 for three faulty wells in all. Field tests on the well on Johnson's land revealed damage from the leak, where seeping salt water rendered the land near the wellhead unusable.

The state, not the operator, will plug the well, according to Railroad Commission records.

"Usable quality groundwater in the area is likely to be contaminated by migrations or discharges of salt water and other oil and gas wastes from the subject wells," according to a Railroad Commission report of contamination on Johnson's ranch. "Unplugged wellbores constitute a cognizable threat to the public health and safety because of the probability of pollution."

Though the agency inspects the cement jobs at well sites throughout the state, critics say that when it discovers a leaky well, it imposes fines, like Lucky's, that amount to a slap on the wrist for the operator - fines that don't begin to address the environmental damage done.

The company could not be reached for comment.

On Johnson's land in Comanche County, it took nearly 30 years for the Railroad Commission to take action against an operator who started drilling a well without enough cement to complete the job, according to commission records and common calculations by the industry. To fill the 3 3/4-inch space between the pipe and earth extending 1,620 feet to the casing shoe - the bottom of the first set of pipes - should take approximately 436 sacks of cement. According to cementing experts, that amount of cement would fill the cylinder encasing the pipe and bring it to the surface - satisfying a Railroad Commission rule. The company's cement report for the site indicates that 380 sacks were used.

The 56-sack difference might not seem like much, considering all the additives an operator can use to accelerate hardening. But no drill bit chews perfect holes into earth, and the geology of each well location plays a critical role in how much water the strata sucks out of the cement mixture as it's pushed down the hole. Drilling a well without enough cement to guarantee the space around the drill pipe is properly sealed, experts say, is tantamount to gambling with the water supply.

The Railroad Commission doesn't have the manpower to scrupulously review every application or inspect every cement job in the state, says Henry, a veteran of decades in the cementing industry. And even if the agency did, most surface casing jobs - setting the pipe and pumping the cement - take place at night, long after inspectors have headed home.

Before applying for a Railroad Commission permit, operators must obtain a letter from the Texas Commission on Environmental Quality that specifies the safe-water mark - the place where operators must drill past to avoid damaging or polluting underground aquifers on their way to the shale or other production zone. For TCEQ, each operator's request requires sifting through more than 300,000 cataloged records that map subterranean Texas.

A three-person administrative staff verifies data in the operator's request, along with geologists who have specific regional expertise, says Ed Block, TCEQ surface casing planner. The staff studies the logs of nearby wells to pinpoint the safe-water spot before a drilling permit is granted.

"If we don't have a log for an area, it is the operator's responsibility to provide one," Block says.

TCEQ's team of nine processed about 11,628 requests from April 1 through Oct. 1 last year. At least half of those operators requested a letter from TCEQ within four days in hopes of expediting drilling. The office customarily takes two weeks to review an application. With the rampant drilling activity in the Barnett Shale, the agency is stretched thin in reviewing about 20,000 applications annually.

"We aim for quicker service, but our workload has been heavy lately with lots of activity," says Block. The current backlog has some geologists helping in regions of the state they don't typically work in, he says.

Henry, the longtime petroleum engineer, says that's part of the problem. Time and expertise matter at every stage of the game: handling the application, reviewing industry data and knowing the geology in the area where the operator wants to drill. But expertise is absolutely critical in the mixing, testing, pouring and curing of cement around the well, Henry says.

Even a minor miscalculation - using too much water or not enough in the mixture - can undermine the stability of the casing, reaping an environmental disaster.

Michelle Wilson, education coordinator for the Portland Cement Association, the industry's leading cement supplier, agrees with Henry that even minor glitches in the mixture can have major consequences.

"It's like Elmer's glue," she says. "If you dilute it, it loses its effectiveness."

Henry, who spent decades cementing and training cementers for Dowell oil field services, says formal training alone can't teach anyone how to mix, test, pour and cure cement at a drilling site. After 50 years in the cement and drilling industries, he says the complexities make it as much an art as a science.

Scofield, who worked the cement truck on Devon's well in Wise County in November, agrees. When working with cement and chemicals in a pressure-cooker environment, Scofield warns, anything can happen.

"I train my guys to think one step ahead," Scofield says. "They need to know what to do."

From his home's breezy porch of brick reclaimed from his childhood school in Lampasas, Henry, now retired, still works to educate others on water safety and proper cementing. His 78-year-old hands deftly sketch pipe plunging deep underground while he lectures on the uncontrolled underground variables drillers must crunch through before hitting the sweet spot for gas. He talks about chemical makeup, compressive strength and myriad terms most people already have forgotten from high school physics.

The lines he sketches are drawn at an angle, so he, too, can see what he's explaining on the traveling easel he used during three unsuccessful campaigns to lead the Railroad Commission, which governs oil and gas production in Texas. He's a patient teacher on what he knows best - cement - and vocal about what he fears the most: bad cement jobs on oil and gas rigs.

It doesn't take long for Henry to grow from soft-hearted sentimentalist to red-cheeked activist.

There's simply no safe cement job, he points out, leaning in and sighing hard. The wind on his porch picks up the paper on the easel, held in place by duct tape, and it crashes to the floor.

As if on cue, Henry starts.

"I'll tell you what," he says of the tape-easel contraption, "that's a typical cement job right there. It wasn't good from the start."