By OGJ editors
HOUSTON, June 29 -- Arkansas has designated two new unconventional gas fields in the Mississippian Fayetteville shale play east of the main Arkoma basin conventional gas-producing fairway.
Southwestern Energy Co., Houston, is pursuing the play centered on a four-county area 25-60 miles north of Little Rock. It plans as much as $100 million in capital spending in the Fayettville shale play this year (OGJ, Jan. 10, 2005, p. 33).
Horizontal wells in the two new fields flowed at rates of 1.4-3.7 MMcfd with flowing pressures of 219-551 psi. Technical data and estimates indicate that the horizontal wells will recover .9-2.3 bcf/well and drain 18-62 acres/well, whereas vertical wells in the same fields would likely recover 300-480 Mcf/well from 20 acres/well or less, Southwestern told the Arkansas Oil & Gas Commission.
The company booked a combined 7.5 bcf of reserves in the play in 2004 from 20 wells, 10 of which were classed as proved, undeveloped locations.
Results from 11 vertical wells with more than 30 days of production in Griffin Mountain field in Conway County indicate a probable drainage area of 20 acres/well or less and estimated ultimate recovery of 150-480 Mcf/well, compared with 30 acres and 580-600 Mcf estimated for the initial two wells.
Southwestern said observed fracture stimulation lengths are about half the estimates in the original reservoir simulation models at Griffin Mountain and that improved EURs may be obtained with longer fracture lengths and-or horizontal wells with transverse frac treatments.
The company estimated that a horizontal well may recover 1.7 bcf or four times the gas of a vertical well at $1.5 million or three times vertical well cost. The company expects variability throughout the play as to gas in place, drainage area, and EUR.
Southwestern as of mid-June held 645,000 net undeveloped acres and controlled another 125,000 net acres held by conventional production in the basin fairway.
It has drilled 48 wells and participated in one outside-operated well. The wells are in seven pilot areas in Franklin, Conway, Van Buren, Cleburne, and Faulkner counties.
Of the 49 wells, 35 are on production, 10 are in completion or awaiting pipeline hookup, and four are shut-in. Seven are horizontal wells.
The two new fields are Gravel Hill on 5,120 acres in Van Buren and Conway counties, and Scotland on 3,200 acres in Van Buren County. The state approved a minimum of 560 ft between completions and as many as 25 wells/640 acres in the two fields.
The Linkinogger 2-9H horizontal well in Scotland field was drilled in 8 days with a 2,032-ft lateral. Stimulated in four stages, it flowed 1.4 MMcfd.
The Payne Family Trust 1-35H horizontal well in the Brookie pilot in Faulkner County was drilled in 19 days with a 2,160-ft lateral, fractured in four stages, and flowed 2.1 MMcfd. The Harrison R2-11 vertical well at Brookie flowed 2.5 MMcfd, and the Bryant 1-11 vertical well flowed 828 Mcfd.
The Sneed 1-31 vertical well, in Southwestern's newest pilot area in Faulkner and Cleburne counties 8 miles east of Brookie, flowed 932 Mcfd.
Southwestern has said the shale is 1,500-6,500 ft deep across the play area.