AAPG’s Explorer of the Year
Barnett at Core of Career
Dan Steward takes pride in doing a good job yet without calling attention to himself.
That’s no small achievement.
It’s difficult to be low-key when your peers consider you to be a crucial contributor to the commercial success of the kingpin of shale gas production in the entire United States.
It’s difficult to be low-key when your peers have decided you’re the AAPG Explorer of the Year.
Indeed, Steward’s unwavering dedication during the almost two decades-long team endeavor at Mitchell Energy to penetrate the shroud of mystery that had long enveloped the Barnett Shale ultimately turned it into the crown jewel of shale plays.
That play was the big reason why Steward was cited as the Explorer of the Year at the recent AAPG Annual Convention in Long Beach, Calif.
“It was a team effort, and I was just a team member” the self-effacing Steward noted.
“We had a helluva good team, and when I was told about the award, friends told me it was important for someone at Mitchell to get recognized for the Barnett.”
‘Gift from God’
You might say it was Steward’s destiny to be involved in a high-profile oil patch success story.
He essentially grew up in the oil fields where he felt right at home as early as the tender age of three years when his dad was a tool pusher on a rig. Steward and his siblings often tagged along, nosing around the location -- an educational (and entertaining) experience off limits to kids today.
Steward later had the opportunity to accompany his then-drilling superintendent dad into the field in western Kentucky. It was there that his love for the oilfield was supplemented by an interest in geology triggered by his acquaintance with a group of geologists who worked the area.
Following graduation from the University of Houston in 1972 with a bachelor’s degree in geology, Steward embarded on a career that would include varying companies and varying assignments.
One of his early jobs entailed working as a mud engineer in Laurel, Miss. He credits this assignment with being a crucial step in his career, providing him hands-on experience with drilling problems and the opportunity to observe the effects of geology on the drilling process.
Interaction with both engineering and operations personnel further enhanced his in-field education.
Mitchell Energy entered Steward’s life when the company lured him away from Shell Oil after he served seven years with the major. When he joined Mitchell in 1981 as district geologist in the North Texas region, his professional life was set to take on a profound new twist.
“The next 21 years proved to be the most challenging of my career,” Steward said. “Mitchell began its evaluation of the Barnett Shale in late 1981, and I am blessed to have been a part of the play essentially from inception to fruition.
“Over the years my positions and responsibilities changed,” he said, “but the Barnett always made up a part of my duties.”
Kent Bowker, one of Steward’s fellow geologists at Mitchell, noted that Steward became the central hub of all Barnett activity in the company. As such, his responsibilities ran the gamut from the reservoir all the way to legal and regulatory affairs.
“I consider the Barnett to be a gift from God,” Steward said. “It became available just as the country was going through a gas crunch, and it had taken us 20 years to get it to that point.”
An Impact Player
The ultimate “explosion” of production from the Barnett, after all the years of head-scratching over its resistance to giving up commercial quantities of gas, is due in large part to a couple of particularly noteworthy events -- and Steward played a key role in each.
Mitchell’s practice of using gel fracs was both expensive and relatively inefficient; at best, the wells were break-even. The decision was made to try more economical water and/or sand fracs, and Steward helped to gain management approval for the initial experiments.
“We applied water fracs to areas where we were break-even,” he said, “and they became extremely profitable. This was not just because they cut costs, but through the use of water fracs, we were able to determine other things we were doing wrong and other ideas we had wrong -- the water fracs gave us a cheap way to test non-commercial or break-even areas.”
The second especially noteworthy event occurred when the Mitchell team realized its gas-in-place numbers were way small.
In 1997, information got out that Chevron had come up with three times more gas for its well in Johnson County.
“We said either we’re in the wrong county or our numbers are wrong,” Steward said. “We then got permission to try state-of-the-art technology, which at that time included gas recovery from cores.”
The coring program included both conventional and pressure cores. The effort determined that in the area where the first gas-in-place evaluation had been made, the numbers were off by two-thirds. In turn, this meant the recovery percentages were far less than thought, and the company began an extensive program of re-fracs and down-spacing and added the previously uneconomic upper Barnett zone to its vertical well completions.
When queried about the future of the Barnett play, Steward noted “there are a lot of things we’re not even thinking about that will happen, but that’s the beauty of a technology play -- technology does not stand still.”
Going strong ... more ...
The Mother Lode
One of the earlier major technology events in the play entailed horizontal drilling. In fact, Steward enthusiastically championed horizontals at Mitchell, where he participated in planning and drilling the wells.
Not surprisingly, Barnett operators have gotten creative with this technology, e.g., applying simultaneous frac jobs on parallel horizontals drilled as close as 500 feet.
A fraced interval is pressured up like a balloon, creating what’s called a positive stress shadow, according to Steward. Each frac creates its own positive stress shadow, and the players think the frac networks are repelled by one another rather than finding each other.
“I believe the future of the Barnett and shale as a whole will involve tweaking the horizontals, tweaking the stimulation on the horizontals, getting a better understanding of fracture containment,” Steward said.
“One of the things in the future is coming up with ways to prevent fracing out of a zone and tying into water in a horizontal well -- or where that has happened, to compensate for it.”
Dual gathering systems -- high pressure and low pressure -- are another possibility for the Barnett. When a well reaches a low producing pressure, it can be moved to that gathering system.
Aside from its considerable contribution to the domestic natural gas supply, the Barnett no doubt provided the impetus to kick off other shale gas plays in the nation.
“The understanding from the Barnett experience is spilling over to all these other shales,” Steward noted. “It doesn’t give all the answers to the other shales but enough understanding that we recognize their potential.”