Fort Worth Basin
The Fort Worth Basin had a major impact on the entire oil and gas industry when it began applying unconventional drilling and completion techniques combining horizontal drilling with multi-stage hydraulic fracture stimulations in the Barnett Shale. The Barnett Shale is located in the Bend Arch-Fort Worth Basin in Texas. It is thought the shale may have more producible reserves than any onshore natural gas field in the lower 48 states.
The Barnett Shale has acted as an important source and sealing cap rock for conventional oil and gas reservoirs in the area. It was thought that only a few of the thicker sections close to Fort Worth would support economic drilling. It was not until the 1980′s with new advances in horizontal drilling and well fracturing technology used by Mitchell Energy, a small independent, that the potential of the Barnett Shale was realized. Mitchell Energy’s innovative team at Mitchell Energy spent ten years and millions of dollars to develop the technology that alone has ushered in a paradigm shift in the energy industry.
Significant drilling activity did not begin until gas prices increased in the late 1990′s. Devon Energy acquired Mitchell Energy in 2002, and has established itself as the leading producer from the Barnett Shale. The success that independents have had in producing from the Barnett Shale has grown to oil and gas shales across North America and the world. The same unconventional techniques are increasingly being applied to conventional “tight rock” reservoirs called resource plays.
Marble Falls Resource Play
The Marble Falls Limestone is a thick sequence of limestone, chert, and shaly limestone that for this report will include all the rock between the base of the Atoka section and the top of the Barnett Shale. Recent activity in the play is centered in Jack, north-central Palo Pinto, south-eastern Young and northeastern Stephens Counties. Historically, the Marble Falls limestone has produced in western Palo Pinto, Stephens, Young, Jack, Eastland, Comanche, Brown, and Erath Counties. There is at present over 1,000 vertical wells that have had large frac completions on the zone with largely high production rates and shallow early declines. Interest in the play is rising fast as the production numbers from these wells become public information. The key consideration with the Marble Falls limestone play utilizing high-volume fracs is large volumes of water production and the costs of disposal.
Salt water production and disposal is a key to exploiting this reservoir economically as 70-80% of fluid production is salt water. These wells have the potential to move 600 to 1000 plus barrels of fluid, which means 100 to 200 barrels of oil with 500,000 MCF to over 1,000,000 MCF of gas. Operators are drilling their own disposal wells to reduce water disposal costs.
The first two entrants in the field, DTE and Swan Production Company assembled leasehold positions of 80,000 and 50,000 acres respectively and drilled over 300 wells collectively. DTE sold its holdings for $255 million to Atlas Resources and Swan sold its Marble Falls assets with 127 wells producing over 3,500 barrels of oil equivalent per day to Brigadier Oil. Other companies have jumped into the play including Newark Energy, which has amassed 140,000 acres of leases and is producing 6,000 BOEPD from approximately 150 Marble Falls wells. Newer wells with 4-5 stage fracs are estimated to yield up to 200,000 barrels of oil equivalent.