Abstract:
Most reservous are heterogeneous in nature, Reservoir heterogeneity can be in the
vertical direction (layered reservoirs) as well as in the radial direction (composite
reselyoirs). Fluid flow is oomphealed for the gas reservoirs because of the inertial and
turbulence effects and the pressure dependence of gas properties, Tills study develops a
semi-analytical model for pressure transient analysis of heterogeneons gas reservoirs.
Reservoir heterogeneity has been considered by drawmg upon the layered and composite
nature of the reservoirs. The diffusivity equation has been solved as a generalized
eigenvalue problem utilizing the pscudopressure and pseudotime schemes. The model
takes into account the high velocity effects, wellbore storage and skin, and different
possible inner and outer bOlUldary conditions. Finite formation damage can also be
modeled.
The model has been validated by comparing the results with those of some analytical
models and simulation results published in the literature. Different schemes for
calculating high velocity effects have been studied and evaluated. For the same amount of
skin, both thin and !inite damaged zone responses have been compared. Both these
responses have been fOlmd to be quite different for certain cases. AU possible outer
boundary conditions, partial penetration and bottom water cond,tions may be studied. Its
application is enormous in the field of pressure transient analysis of gas reservoirs. This
versatile model, to my knowledge, includes more features for gas reservoirs than any
other previously published pressure transient models.
