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The following is a condensed list of the user-specified General Options
found in MFrac. The modeling options for MFrac are divided into
Fracture Options (which control the fracture model), Proppant Options
(which control the proppant transport model), and General Options (which
control basically everything else). For a complete list of all
options available in MFrac, please refer to the Meyer Fracturing Simulators User’s Guide.
Simulation Method
Design Mode
Design Mode supports the traditional process for hydraulic fracture
design, in which the fracturing engineer manually designs and optimizes the
fracture treatment. In this mode, MFrac allows the engineer to input
the desired fracture length, slurry volume, or treatment schedule.
MFrac will then compute the characteristics of the fracture(s) that would
be produced by the given design. The program can also use the
formation and treatment data to calculate various fracture and proppant
transport characteristics.
Replay/Real-Time Mode
Replay/Real-Time Mode is used to replay or performing real-time fracture
analysis using the data collected during a treatment. This procedure
requires the use of MView as the real-time or replay data handler.
There is essentially no difference in the procedures used internally by
MFrac to perform real-time or replay simulations. The difference between
these methods only involves the means of inputting data, which is handled
by MView. Both methods permit pressure matching, fracture geometry
prediction, and proppant transport simulation.
Real-Time
The Real-Time options are available only in Replay/Real-Time Mode.
If MView Concentration is selected the proppant concentration will be taken
from the replay/real-time data as sent to MFrac by MView. If the Input
Concentration button is selected the proppant concentration used by MFrac
will be taken from the values specified in the Treatment Schedule.
Generally, the MView Concentration is desirable unless the actual proppant
concentration injected is not available.
The Synchronize Well Solution radio button is used to synchronize the
numerically calculated time steps for wellbore events with the
replay/real-time data.
Synchronizing the wellbore solution with the incoming real-time or
replay data enables for very refined calculations of the wellbore and
near-wellbore frictional pressure losses. Since the fracture net
pressure is not as dependent on the instantaneous rate changes, this
provides the capability to run the fracture model with a greater time step
while still simulating the effects of rate changes on frictional losses in
the wellbore and near well region.
Net Present Value
The Net Present Value option is available only in Design Mode.
When the NPV option is turned On, MFrac automatically sets the Treatment
Schedule to Auto Design and the Treatment Type to Proppant. For this
option, a maximum fracture length is specified in the treatment schedule.
MFrac then automatically calculates the proppant distribution and fracture
conductivity for a number of incremental fracture lengths up to the maximum
value specified. The purpose of this type of analysis is to optimize the
design length and conductivity for propped fractures. This process is
accomplished by coupling our analytical production simulator MProd to
forecast productivity for each subdivision of the fracture length. MProd,
in turn, produces output used by MNpv to perform Net Present Value economic
optimization calculations.
Turning NPV Off enables the simulator to perform in standard Design,
Replay/Real-time or Auto Design mode. This is the general mode of operation
unless an NPV analysis to optimize fracture length is desired.
Fluid Loss Model
Click here to download the Meyer 2009
User’s Guide, including more information about Fluid Loss
The rate of fluid loss to the formation is governed by the total leakoff
coefficient C. The three types of flow resistance mechanisms making
up C are: 1) CI - Leakoff viscosity and relative
permeability effects, 2) CII - reservoir viscosity and
compressibility effects and 3) CIII - wall building
effects.
This option determines which fluid leakoff model is used. The fluid loss
model options include specifying the total leakoff coefficient (Constant
Model) or the CIII coefficient and the corresponding
components which comprise CI and CII
(Harmonic or Dynamic Models).
If Constant is selected, the total leakoff coefficient, C, is
entered in the Fluid Loss Data screen. The total leakoff and spurt loss
coefficients are then input as a function of depth to characterize fluid
loss in the fracture at different intervals.
When either the Harmonic or Dynamic models are chosen, the filter cake
coefficient (CIII) and reservoir diffusivity parameters are
input in the Fluid Loss Data screen for each layer. The CI
and CII coefficients are then calculated from the input
reservoir data and fracture propagation characteristics. The total leakoff
coefficient is then calculated internally as a function of differential
pressure.
Treatment Type
This selection determines the type of fracture treatment. The Treatment
Type can be either oriented towards a propped (Proppant) or acid (Acid)
fracture. In addition, the treatment can accommodate an optional foam
schedule by checking the Foam box. When Foam is checked, MFrac will include
compressibility effects.
Treatment Design Options
The treatment design options are only available if the Simulation Method
is in Design Mode and the Treatment Type selected is Proppant with no Foam.
The default setting is Input for all other cases.
In MFrac, the pumping schedule can either be input manually or
determined automatically. When Auto Design is chosen, the desired design
fracture length or total slurry volume is input in the treatment schedule
dialog box. Depending on the Proppant Transport Methodology selected,
specific criteria for controlling the proppant scheduling will also be
required.
When Input is chosen, the pumping parameters must be entered into the
Treatment Schedule screen. The exact data input required will depend on
selections made for other options (e.g., ramped proppant scheduling, user
specified proppant settling, acid fracturing, etc.).
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