Mixing it upApril 13th, 2012 | Posted by in RD20
Drilling company sees changing approach to drilling surface holes as an advantage for the industry
Danny Tate is the new district manager for the drilling division of Key Energy Services. After 18 years in the field, Tate finally took an office job. He sees this as an opportunity to make changes in the industry and build something along the way. It’s with this philosophy that he is embracing the mixed fleet approach with Key’s fleet of rigs in the Permian Basin.
Currently the company first uses an Atlas Copco RD20 to drill 500-foot surface holes and set surface casing. Then an HP Flex Rig moves over the hole to take it to total depth. Cost reduction is the biggest advantage Tate sees in using this two-drill, or mixed-fleet, drilling method. However, looking at the overall environmental difference, he sees a change in the drilling culture.
Self Sufficiency—reduced equipment and manpower
The advantage of starting off with an RD20 to drill the first 500 feet is that the smaller drill rig can get on and off the pad in a shorter period of time. With fewer components and equipment to rig-up, the overall process is faster. From pulling on-site through drilling, casing and cementing the hole, the process takes an average of two to three days. The company can drill 10 to 12 holes a month at diameters of 12 ¼ or 14 ¼ inches.
The RD20 and its support equipment takes just four hours to rig up, compared to the four days it takes to set up the company’s super-single drill rigs. With only one mud pump and two diesel pumps to move fluid in and out of the pit, the site is light on equipment necessary to drill the well.
Also, fewer pieces of ancillary equipment are required. A diesel and water tank, tool trailer, dog house, and two light towers are easily loaded or towed to the next drill site.
Equipment requiring a forklift to load includes the drill pipe, collars, and pipe racks along with a tooling box of smaller equipment such as bits, slips, cable bales, and tongs.
Moving requires two flatbed semitrailer, a sliding skid-deck truck and the crew’s pickup trucks. Drill Superintendent Jeff Woods said he is impressed with how self-sufficient the RD20 site is. “A two-day surface hole translates into less time over the hole than a larger rig, which really adds up,” he said.
One important part to add to the drill string according to Tracy Wells is the shock-sub. They have many connections using a saver-sub and crossovers dropping production pipe sizes from 6 ½ inches to 5 ½ and 4 ½, but the shock-sub is key to the string. “The shock-sub takes a beating, not the rotary head. It takes 50 percent of the shock out of the string,” he emphasized.
The shock-sub will be rebuilt every six holes or so. Driller Adam Wells pointed out that while in rock a driller will put 7,000 to 8,000 pounds of weight on the tricone bit, the Redbed formation requires less, only about 5,000 pounds. The Redbed is a reddish-colored, clay-like shale stratum, roughly 200 to 1,400 feet (61 to 427 meters) from surface in the West Texas Permian Basin oil field.
The formation here changes often, Wells said, which causes him to be attentive on the controls. “There are times the bit will go quiet and just drop, it’s not uncommon.” This is a result of softer or sandier formations that can require swabbing the hole to clean it.
Each well is different, one of the crew members pointed out. One well near the airport, he said, drilled as smoothly as a hot knife through butter, taking half the time of a typical well.
With a tricone in this formation they will pump 320 gpm of water while they drill, which was about 50 to 100 pounds of pressure. “We are not concerned with pressure when drilling. It doesn’t take much to lift the cuttings,” said Tracy Wells.
Fresh water is used for flushing, although they will sweep the hole with a polymer occasionally, about every other joint, and when the well is complete. This ensures integrity of the hole and helps to lift the cuttings. The crew trips out overnight to ensure nothing falls back on the bit.
The crew only works daylight shifts, an average shift lasting 12 hours. Occasionally they’ll work a longer day to get a hole cemented because they can’t miss their window with the well service company. With a penetration rate of 120 feet in eight hours, the crew averages a well every two days. Total time with cementing included means the crew can move every few days.
Tool pusher Tracy Wells said this crew works well together, resulting in a 10 to 12 well-per-month schedule.
Key’s philosophy and a culture of growth
Tracy Wells said using the RD20 rather than a larger rig requires a new way of thinking for him and a bit different work style. He said, “Paperwork requires more time off the rig and in the site’s trailer. I have to keep the same records as for a larger rig that moves slower.”
Danny Tate realizes there is a change in drilling at the corporate level, too. “We are creating a new class of oil field worker. It’s a new culture out there,“ he said.
Tate also brought up the work schedule. Since the RD20 crew only operates during the day, it reduces the potential for fatigue problems. “As far as an oilfield job, this is about as close to a 9 to 5 job as you’re going to get,” he said.
In addition to the speed at which they can move from hole to hole, he specifically likes the safety environment around the RD20. “Everyone’s receptive to the increase in safety awareness practices, and the RD20 is a safer rig. I know our customers like this, too.”
Speed and mobility equal cost reduction
The customers also like the reduced cost that comes with the RD20. Its day rate is a third the cost of a big rig, which is really noticeable when a rig has to sit while the cement sets up. Once the surface hole is drilled and cemented, the RD20 moves off while the cement cures. A big rig would have to wait two to three days before it could go back in the hole.
Tate pointed out the moving costs are also a lot less with the RD20. “It costs $70,000 to $80,000 to move a big rig versus $5,000 to $6,000 for the RD20.”
Overall there is just less to worry about with the RD20. Tate said, “I’d like to have three of them working, just because of the problems I don’t have with them.”
“I know there is so much more you can do with it, but this rig was really well designed for surface holes,” said Tate.
Tate summed up his opinion of the rig by focusing on the costs associated with it. “It’s a money saver. It’s self-sufficient and it doesn’t cause problems. Bottom line, it saves our customers money and makes us a little, too.”