Well Analysis in Naturally Fractured Reservoir Using Elliptical Flow

Naturally fractured reservoirs are anisotropic
systems whose flow characteristics depend on the
fractures network. Their permeability variation is
not only stratigraphic in nature, but is also caused
by the fractures distribution, orientation and
permeability impairment within the fractures caused
by pressure solution or mineralization. The
reservoir becomes more complex when both the matrix
and fracture exhibit anisotropy and have the
capability to flow into the wellbore as in the
double permeability case. Well test analysis in
these reservoirs has been based on the radial flow
model, even when it is widely believed that such
reservoirs are anisotropic. The radial flow model is
however only applicable to purely homogeneous
system. It cannot provide a complete formation
analysis in anisotropic system. This study therefore
presents a new method of estimating permeability
anisotropy in naturally fractured reservoirs. The
maximum permeability is attributed to the large
scale fractures while the minimum permeability may
be due to the small scale fractures orthogonal to
the large scale fractures or the matrix.

Autorentext

Alpheus Igbokoyi is a Reservoir Engineer with Shell Petroleum
Development Company, Nigeria. He received his PhD degree in
Petroleum Engineering from the University of Oklahoma, USA.
Prior to his PhD program Alpheus worked as Drilling/Reservoir
Engineer both in Texaco and ExxonMobil. He was a part-time
lecturer at the University of Ibadan.

Klappentext

Naturally fractured reservoirs are anisotropic
systems whose flow characteristics depend on the
fractures network. Their permeability variation is
not only stratigraphic in nature, but is also caused
by the fractures' distribution, orientation and
permeability impairment within the fractures caused
by pressure solution or mineralization. The
reservoir becomes more complex when both the matrix
and fracture exhibit anisotropy and have the
capability to flow into the wellbore as in the
double permeability case. Well test analysis in
these reservoirs has been based on the radial flow
model, even when it is widely believed that such
reservoirs are anisotropic. The radial flow model is
however only applicable to purely homogeneous
system. It cannot provide a complete formation
analysis in anisotropic system. This study therefore
presents a new method of estimating permeability
anisotropy in naturally fractured reservoirs. The
maximum permeability is attributed to the large
scale fractures while the minimum permeability may
be due to the small scale fractures orthogonal to
the large scale fractures or the matrix.