A New Theory for Interpreting Rate Decline Trends in Solution-Gas Drive Reservoirs
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A number of attempts have been made to establish the theories
of rate decline in solution-gas drive reservoirs with multiphase
flow. However, none of these attempts have established a functional
link between the empirical and the theoretical domains of
decline curve analysis for such reservoirs. The absence of such a
link has inhibited the formulation of simple techniques for reservoir
properties estimation. The purpose of this work is therefore
to establish the missing link.
In this work, functional relationships between the empirical
bemp and the theoretical bth were derived. The derivation was based
on a novel definition of a new parameter known as time-weighted
average of the theoretical exponent bth .This new parameter was
found to be related to the empirical exponent bemp, thus establishing
the link. A reservoir simulator was used to generate sets
of production data used in verifying the derived relationships. Results
presented in this paper show that the relationships derived
herein are valid, even for heterogeneous reservoirs. The work
also offered theoretical justifications for the various ranges of bth
values, and for the first time, four distinct rate decline regimes in
solution-gas drive reservoirs were identified. Sensitivity analyses
were performed on the results. The effects of non-Darcy flow on
decline parameters were also investigated.
Lastly, this work provided a mathematical justification for the
existence of the hyperbolic family of curves in decline analysis of
solution-gas drive reservoirs
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TP Chemical technology