Crisman Annual Report 2009 - Harold Vance Department of ...

Gas Shales Simulation and Production Data Analysis
Objectives
Rate decline forecasting of wells in tight gas/shale
gas reservoirs using modern decline curve analysis
can result in dramatic overestimation of reserves.
The cause for this error is usually incorrect
interpretation of transient flow data (i.e., data which
are NOT affected by reservoir boundaries).
The extremely low permeability of shale gas and
tight gas reservoirs causes the transient flow period
to last years or decades. Additionally, the physics
of transport and storage controlling the gas flow in
shale gas systems is complex and varies markedly
between reservoirs. Finally, posing yet another
complication, most wells in these reservoir types
are drilled horizontally and hydraulically fractured
multiple times.
the flow concept of van Kruijsdijk and Dullaert, and
showed how production data analysis can be used to
identify these flow regimes.
In 2009, TAMSIM was used to study the effects of
variation of numerous reservoir and completion
parameters on well performance. One paper
(SPE 124961: A Numerical Study of Tight Gas
and Shale Gas Reservoir Systems) published this
year served to characterize the effects of sorption,
fracture conductivity, fracture spacing, and matrix
permeability for various assumptions of single- and
dual-porosity reservoirs, with and without laterally
conductive layers. This work was presented at the
The objectives of this research project have been to
build a numerical simulator for shale gas reservoir
systems and to study the complex flow regimes
found around horizontal wells with multiple hydraulic
fractures and enable identification and interpretation
of these regimes through production data analysis.
Approach
Our approach has been to determine the proper
theoretical foundation for creating a tight gas/shale
gas simulator, and to implement these concepts
into the purpose-built numerical simulator TAMSIM,
which is descended from the TOUGH+ family of
numerical simulators.
To determine a sound theoretical basis, we
undertook a literature search, focusing on the
physics and simulation of coalbed methane, tight
gas, and shale gas reservoirs. This literature review
also entailed research into specific storage and
transport mechanisms such as flow in naturally and
hydraulically fractured porous media, diffusion in
porous media, and surface sorption.
In 2008, work was focused on implementation and
validation of the capability to accurately simulate
horizontal wells with multiple transverse hydraulic
fractures. This part of the functionality has been
validated against various other methods, and used
to provide synthetic cases for study and history
matching. Through simulation, we created clear
visualizations of the progression of flow according to
The progression of flow regimes in multiple fractured horizontal wells
(van Kruysdijk and Dullaert [1989])
Project Information
1.2.5 Shale Gas Reserves Estimation
Contacts
Tom Blasingame
979.845.2292
t-blasingame@tamu.edu
C. Matt Freeman
CRISMAN INSTITUTE
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Crisman Annual Report 2009