By OGJ editors
HOUSTON, Apr. 27 -- Estimated remaining recovery from the Kansas and Oklahoma portions of giant Hugoton gas field could be as much as 20 tcf of gas, a new study implies.
The two-state portion of the field has yielded 35 tcf of the estimated 67.9 tcf in place since discovery in 1922 from more than 12,000 wells, the Kansas Geological Survey said.
A computer model created in the 2-year study may help operators extend field life and more efficiently recover a majority of the remaining gas, the survey said. KGS researchers created a 108-million-cell, 10,000-sq-mile, 3D geologic and petrophysical model of the field.
Recovery factor is 65% in Grant and Stevens County in the central part of the field compared with 51.5% for the entire two-state field, never before been studied publicly as a whole.
Indispensible proprietary data, including 8,200 core samples, contributed by 10 industry partners helped determine how much gas remains in the field and where it is located, the researchers said.
For example, they found that in most places the gas column is continuous between the Hugoton Chase and Panoma Council Grove formations. The two are regulated as separate formations in Kansas.
Production has fallen to just over 250 bcf in 2006 from 600 bcf/year in the 1960s.
Production appears likely to be sustainable if the integrity of 40 to 70-year old wells can be maintained.
"Production projected to 2050 in the 28 Flower model wells suggests that most of the additional gas recovered (21.3 bcf) is primarily from zones having lower permeability, average well production is estimated to be 21 Mcfd/well, decline rate is <2%, and the recovery factor increases to 81% of OGIP," the study said.
The field has a sloped gas-water contact. The presence of water in pore spaces of low-permeability reservoirs is important for accurate volumetric calculations and because water occupies critical pore-throat space and can greatly diminish gas permeability, even in rocks at "irreducible" water saturation, the study said.
High permeability zones are at 25 psi and are 95% depleted of gas. Zones with moderately low permeability are at 200 psi, are 45% depleted, and contain significantly more gas than high permeability zones.
One observation, based on a study of 38 scattered wells, showed a tendency for the upper Chase to be depleted while the Lower Chase and Upper Council Grove are less depleted.
