Published: 10/30/2011
Published: 10/30/2011
Recently, we have developed a new methodology to model hydraulic
fracturing-induced fracture networks and subsequently simulate a shale gas
reservoir as a dual-porosity system. The reservoir geological, geophysical and
petrophysical characteristic data are integrated to build geological framework
and property models. Microseismic responses are used to delineate stimulated
reservoir volumes. Microseismic events and/or natural fracture intensity are
utilized to estimate the initial intensity of this induced fracture network.
The fracture intensity is further calibrated using hydraulic fracturing job
data and reservoir geomechanical properties through a fracture propagation
mechanism.
In this paper, we show a significant extension of the
modeling methodology to handle more general scenarios of stimulated shale
reservoirs. We introduce a superposition technique to process the overlapping
of microseismic mapping responses from different stages of
“simul-frac” and/or “zipper-frac” operations in a
single well or in multiple wells. The improved method takes into account
different fracture network geometries. Various models for volume expansion by
stimulation are investigated for proppant placement estimations. In the ideal
viscous fluid-proppant transportation scenario, proppant and fracture
conductivity distributions can be calculated with mass conservation
corresponding to different fracture network geometries and volume expansion
models. Both fracture intensity and fracture network conductivity are used to
create dual porosity simulation model inputs. Considering that for most shale
gas wells there is no microseismic data, we introduce a modeling procedure
incorporating treatment data and geomechanical parameters in which the fracture
network geometry can be specified based on well completion data and field
experience. We also present the general workflow through a demo case from data
input, fracture network geometry configuration, calibration and calculations,
and output of dual-porosity model parameters for reservoir simulation. This
extended methodology can be efficiently applied not only to modeling of
single-well shale gas reservoir but also to modeling of multiple wells where
their drainage volumes are inter-connected. A field example demonstrates the
applications of the new modeling methodology, which provides a unique,
effective means for modeling and simulation study as well as history-matching
calibration of stimulated shale gas reservoirs.