Well Test Analysis of a Horizontal Well in a Completely Bounded Reservoir
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Date
2022
Authors
Kitungu, Nzomo Timothy
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Well test analysis as an important part of reservoir engineering has gone through
tremendous improvement through the years since the discovery of oil. This is in terms
of the tools used, the technology involved, and the mathematical modeling involved.
Since most oil reservoirs are underground and in some cases thousands of feet from
the surface, it’s impossible to physically observe them and see how they behave or
determine their character. Mathematical models play an important role in reservoir
system characterization by predicting the well and reservoir behaviour and properties.
Over the years horizontal wells have proved that they are more productive compared
to vertical wells. In this dissertation, possible mathematical models that can be applied
in well test analysis for horizontal wells in a completely bounded oil reservoir are
developed. In developing the models, source and Green’s functions are used. Using
these functions, dimensionless pressure and dimensionless pressure derivative
distributions in real time are derived. Mathematical analyses of the models developed
and how they can be applied to characterize a completely bounded oil reservoir
penetrated with a horizontal well are presented. All possible flow periods and the
effects of reservoir, fluid properties and well design on horizontal well performance
are investigated and presented. The effects of reservoir anisotropy on well
performance are also investigated. The results of this study show that assuming
isotropic cases might reduce the accuracy and reliability of the results obtained and
thus recommend consideration of anisotropy in computations. This should be in all
the three directions. Further, the results of this study show that well design, directional
permeability and reservoir geometry will affect the horizontal well performance
differently at early flow time. This applies when the infinite-acting flow is considered
as compared to the pseudosteady state flow at late time. It is also noted that the
number of flow periods can be many; four full and at least three transitional flow
periods from inception of early transient, when the well is infinite-acting, to late
transient, when all the external reservoir boundaries are felt. The results also suggest
that oil wells that are in the same reservoir and closely spaced will experience
pressure communication (interference) faster and vice-versa. Thus, well pressure
interference affects well performance. The results obtained in this study can be used
for complete reservoir system characterization and to investigate the best well design
for optimum oil recovery in a bounded well reservoir penetrated with a horizontal
well.
Description
A Thesis Submitted in Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Applied Mathematics in the School of Pure and Applied Sciences of Kenyatta University, April, 2022
Keywords
Well Test Analysis, Horizontal Well, Completely Bounded Reservoir