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Evergreen files for coalbed exploration project at Pioneer unit near Wasilla Company plans two pilots of four wells each to depths no greater than 2,999 feet in 12 months beginning July 15 to test for coalbed methane Kristen Nelson PNA Editor-in-Chief
Evergreen Resources Alaska Corp. is permitting a project to drill an eight-well exploration project to test the ability of the coals in the company’s 72,000 acre Pioneer unit in the Matanuska Valley to produce natural gas.
In a 12-month operations plan filed with the state the company said it is proposing to drill, complete and test the wells in two areas called pilots. In each pilot the wells will be laid out with one well in the center, a second well 1,000 feet to the north of the center well, a third well 1,000 feet to the southeast of the center well and the fourth well 1,000 feet to the southwest of the central well.
“It is important to understand that we currently propose an exploration program designed to test the coal’s ability to produce natural gas,” Evergreen told the state.
“Exploration pilots incorporate a pod of wells being produced within close proximity to one another. In a development program, wells will be spaced at greater distances,” the company said. Unit formed by Unocal Evergreen bought the Pioneer unit, 30 miles north of Anchorage between Wasilla and Houston, from Ocean Energy and Unocal in May 2001. Unocal formed the unit in 1997 to explore for coalbed methane.
Evergreen said it would only drill two pilots, but would permit three.
“By having approval for more than two pilots,” the company said, “we help ensure that the unit’s well obligations can be met even if land, permitting or other problems arise.”
The pilots are planned for an area north of the Parks Highway between Wasilla and Houston. Evergreen said it selected the sites to meet geological and engineering considerations and also to minimize “possible impact on the surrounding community.” The pilots are all “away from residential houses and on lands where the owner has both the surface and the mineral rights.” Different than previous plans Evergreen said this plan is different than previous coalbed methane development proposals at Pioneer.
“For example, by utilizing our own equipment, Evergreen will reduce well location, drilling and completion time by 40 percent,” the company said.
The pilot No. 1 location is one and a half miles northwest of the intersection of the Parks Highway and Big Lake Road, on land where a private party owns both surface and mineral rights. The company said it is finalizing an agreement with the owner to drill on the property this summer.
Pilot No. 2 and pilot No. 3 are along Church Road, two and a half miles north of the Parks Highway. Both the surface and the minerals are owned by the Alaska Division of Lands or the Mental Health Trust. Water injection well will be used Ocean Energy drilled a water disposal well and built facilities and Evergreen said it will use the well and facilities.
Evergreen said it would begin building locations and roads July 15 and begin drilling Aug. 1. Fracture stimulation of the Pioneer 1702 15DA water disposal well and hook-up of existing facilities will begin July 25.
Evergreen said it will finish the work Ocean Energy started at the water disposal well. Ocean Energy partially constructed surface water-handling facilities and drilled the water disposal well, set casing and perforated.
Evergreen said it plans to break down existing perforations, place a hydraulic fracture treatment on those perforations and hook up the existing surface disposal facilities.
The company said it has no plans to place other existing wells — the BLT No. 1 reentry, the Pioneer 1702 15DD and the Pioneer 1702 14CC — on production in 2002, but plans to clean-up those sites and secure them with gates and fences. Air drilling planned Evergreen will be drilling with air rather than with mud.
“Air is chosen because of its lower impact on the environment and because air imparts less damage to the coals,” Evergreen said.
“Since none of the specialized drilling, cementing and completion equipment, which is required for successful coalbed methane development exists in Alaska, Evergreen will utilize its own equipment and personnel to perform these operations,” the company said.
Location and road building will average two to three days per site. Drilling the conductor will also take two to three days per site.
Eight wells will be drilled in two pilot locations in August. In each pilot area, Evergreen said it will core one of the four wells. The company estimates it will take 4.5 days to drill the cored well and 3.5 days each to drill the other wells, including mobilization and demobilization, logging, running casing and cementing the surface and production casings.
While site preparation will be done in daylight hours, drilling will be a 24-hour operation. Production testing over the winter Completing the wells is estimated at two to four days per well and includes running a cement bond log, remedial cementing if required, perforating, hydraulic fracturing and cleaning up the well after fracturing. This work will be done in daylight hours.
Production testing, including installation of production equipment (tanks, down-hole pumps and measuring equipment) and placing the well on production, will begin in October and continue through July 15, 2003. The site will be secured with fences and locked gates. Equipment installation will average four days per well and unless a major problems requires immediate attention work will be done during daylight hours.
Wells may require additional work during this phase — re-fracture treatments or changing the pump. Produced water will be trucked from the site to the water disposal well approximately seven miles from each pilot. Coal in Tyonek formation A local water well contractor will drill and set conductor casing to plus or minus 20 feet below the gravel zone which is 100 to 200 feet deep.
Evergreen’s drilling equipment will drill the remaining sections of the hole: surface portion to at least 100 feet below the fresh water zone and production hole to a depth no greater than 2,999 feet.
Evergreen said its drilling equipment is a truck-mounted highly modified water well rig.
In air drilling the well is being drilled under-balanced, Evergreen said, and well control is a concern. “Fortunately, however, for coal bed methane drillers, very little gas is produced during the drilling process. This is because the coals require significant de-watering before gas is produced.”
Gas produced during drilling is usually from an adjacent sandstone formation, the company said. “In these cases, key to any under-balanced drilling operation is the ability to keep the drilling area free of explosive concentrations of natural gas” and fortunately “very little gas is liberated” during coalbed methane operations, Evergreen said.
The company said it will use a diverter, a series of check valves in the drill string and a cement truck on the site in stand-by mode to manage any natural gas that may emanate from the well. Cement modified for Alaska Evergreen has its own cementing equipment and uses proprietary cement blends designed for coalbed methane. The company said it is modifying the cements to work in Alaska’s colder climate.
The company’s cementing equipment is working in Ireland and the United Kingdom for Evergreen Resources (UK) Ltd. and will be shipped to Alaska for work at Pioneer.
After cementing, Evergreen uses its own hydraulic fracture equipment to hydraulically fracture stimulate the target coal seams. In hydraulic fracturing, gelled water, surfactant (soap) and nitrogen gas is pumped at pressures and rates high enough to crack the rock. After the fracture is established, Evergreen said, sand is mixed in and the slurry is pumped into the crack created, typically one-half inch wide and 200 feet long.
Fracture treatments, the company said, “increase the cross sectional area that gas and water can flow from the formation and into the well bore” enhancing the well’s ability to produce. Nine-month production test Evergreen said there will be a nine-month production test, with a progressive cavity pump installed to remove water from the coals. Water rate, gas rate and pressures will be recorded and analyzed to determine if the coals will produce economic quantities of gas.
A six foot by eight foot shed will be installed over the natural gas powered six-cylinder engine powering the pump to protect the engine and to mitigate noise.
Gas produced during the production test will be vented or used to keep the produced water and gas lines from freezing.
Water produced, estimated at 150 to 400 barrels per day per well, will be piped to two 500 barrel tanks and then trucked to the injection well 1.4 miles south of the Parks Highway on Vine Road, where tanks and pumps are in a 60 foot by 36 foot steel building. Evergreen said hauling will most likely occur on a daily basis, although if the wells produce on the higher end of the company’s water production estimates, several trips per day may be needed. Pilot locations Pilot No. 1 is on a 109-acre parcel in sections 1 and 2 of township 17 north range 3 west, Seward Meridian , 8.5 miles west of the city of Wasilla and 3.5 miles southeast of the city of Houston, 1.5 miles northwest of the intersection of the Parks Highway and the Big Lake Turnoff. A private party owns both surface and mineral rights.
Pilot No. 2 is in the southeast corner of section 30 T18N R1W, SM, 2.5 miles north of the Parks Highway along the west side of Church Road. Surface and minerals are owned by the state of Alaska, Division of Lands; Alaska Mental Health trust lands adjoin the lease.
Pilot No. 3 is in sections 20 and 29 of T18N R2W, SM, one-half mile east of the intersection of Church Road and Pitman Road, approximately four miles northwest of Wasilla. Minerals and surface on the north 40 acres are owned by the Division of Lands; minerals and surface on the south 40 acres are owned by the Alaska Mental Health Trust.
Pad size for drilling and completing the well is 175 feet by 200 feet. A total of 12,200 barrels of water is needed for drilling and completion; additional water may be required during the production-testing phase of the plan for remedial well operations.
During drilling and hydraulic fracturing of the Pioneer 1702-15DA water disposal well, all water will be purchased from local suppliers. As wells are fracture stimulated and placed on production test, produced water will be used.
Evergreen estimates that roughly 7,000 barrels of water will be purchased and the remainder will come from produced water.
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