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Tight Gas Reservoirs Low Permeability Reservoirs The main contributor of unconventional gas in the US. By definition any reservoir with a permeability of .1 md or less is a tight gas reservoir. Defined by the NGPA of 1978 This is matrix permeability Most have much less perm, .01 or less. - PowerPoint PPT Presentation
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Tight Gas Reservoirs
Low Permeability Reservoirs
The main contributor of unconventional gas in the US
By definition any reservoir with a permeability of.1 md or less is a tight gas reservoir.
Defined by the NGPA of 1978
This is matrix permeability
Most have much less perm, .01 or less
Not all tight gas reservoir act the same
Very low matrix perm w/ natural fractures
low matrix perm wo/ natural fractures
Gas shales used to be listed as tight gas
By Definition Tight-Gas Reservoirs are Anisotropic.
.1 md Permeability will not produce economically.
Formation must be Naturally Fracturedand/or
Hydraulically Fractured
Which gives them directional Permeability.
Kmax
Kmin
Drainage in an Anisotropic Reservoir
Traditional Methods for finding Anisotropy
Oriented CoresBest method to find direction of anisotropy
Multi-well Interference TestsCan find values for Kmax and Kmin Also the direction
The low perm makes these test very hard to run unless the spacing is very tight
Alternative Methods for finding Anisotropy
Find Keff & Kmin
Then use
minmaxKKKeff
Methods to optimize production in Tight-Gas Reservoirs
Horizontal Drilling Regional Fractures Multi staged Frac Jobs
Infill Drilling All Reservoirs with large spacing
From a presentation 11 years ago
Within the next 10 yearsgas demand in the United States will increase from 21 tcf to 30 tcf of gas annuallyToday the U. S. Produces 18 tcf of gas annually
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