Data loading and editing
Saphir NL offers a wide variety of loading and editing
capabilities in order to arrive at a quality checked and
consistent set of rate and pressure data. Although this
is not the most riveting of subjects, Saphir NL can
load an unlimited number of gauges, rates, pressure
and other data in almost any format including ASCII,
Excel™, PAS and databases of all kinds via OLEDB &
ODBC. Saphir NL has real time links with acquisition
systems, data drag-and-drop from other Ecrin modules
and Diamant Master, which can identify build-ups and
initialize Saphir NL on a single click. Multi-layer rates
may also be imported from Emeraude.
Data QA/QC and datum correction
Saphir NL offers a comprehensive range of interactive
QA/QC tools including trends, tidal correction, gradient
analysis and the possibility to compare various gauges
to detect sensor drifts and wellbore effects.
Saphir NL can define or import VLP’s and well intake
models, either from Amethyste or standard file import.
VLP’s are used in conjunction with analytical and
numerical models to simulate the pressure at gauge
depth or at surface. Alternatively they can be used to
correct pressure data a priori to reservoir depth.
All analytical and numerical models may be used to
generate a virtual gauge on which a complete analysis
may be simulated. This can take into account gauge
resolution, accuracy and potential drift in order to
select the appropriate tools or to check if the test
objectives can be achieved in practice.
Extracting ΔP and deconvolution
One or several periods of interest, generally shutins,
for one or several gauges may be extracted and
presented on a semi-log and loglog plot, the latter
integrating the Bourdet derivative.
Deconvolution can be used to combine several
successive shut-ins into a longer ‘virtual production’.
Available methods are (1) von Schroeter et al, (2)
Levitan, (3) Houzé et al and (4) a hybrid combination.
Saphir NL v4.20 now integrates the Levitan material
Additional specialized analysis plots can be created
with options tailored to specific flow regimes. These
include very short-term tests or FasTestTM for
perforation inflow testing and predefined types such
as MDH, Horner, square root and tandem root.
Saphir NL offers a comprehensive built-in analytical
catalog combining built-in well, reservoir and boundary
models, complemented by external models (see Technical references
). Interactive ‘pick options’ are offered for
most parameters for a first estimate by selecting a
characteristic feature of the model on the Bourdet
derivative. There is the option to use the AI package
‘KIWI’ as a guide. Additional capabilities include
rate dependent skin, changing wellbore storage,
interference from other wells, gas material balance
correction, well model changing in time, horizontal
and vertical anisotropy.
Numerical models are used for geometries beyond
the scope of analytical models. This is predominantly
2D but with 3D refinement where needed. The most
complex numerical model to date solves the problem
of fractured horizontal wells.
These numerical models also address nonlinearity.
Pseudopressures are replaced by the exact diffusion
equations for real gas, non-Darcy flow, pressure
related physical properties, multiphase flow, water
and gas injectors, water drives, and more recently
desorption models for shale gas and CBM.
Use of Rubis sectors
A sector of a Rubis full field 3D reservoir model can
be imported and run directly in Saphir for a given time
range. In v4.20 the starting point is the dynamic state
of the simulation at the extraction time. This enables
Saphir NL to simulate 3D / 3-phase flow with gravity
and in complete coherence with the reservoir model.
An unlimited number of commingled layers that have
individual initial pressures can be modeled analytically
or numerically. Connected layers can be modeled
numerically. Analytical models can superpose
internal or external single layer models. Stabilized
or transient rates can be loaded and associated with
any combination of contributing layers. Rates may be
loaded directly from Emeraude analyses. Optimization
is performed on both pressure and layer rates.
Optimization and sensitivity analysis
Nonlinear regression is used to optimize the model
parameters. This may be automatic or user controlled
from a list of variable parameters, acceptable range,
and weighting of the data. Optimization may be
performed on the extracted period(s) or on the
whole production history. Confidence intervals may
be displayed. Sensitivity analysis may be performed
by running the same model for different parameters.
AOF / IPR
AOF and IPR analyses are available for vertical,
horizontal and fractured wells. Test sequences may be
flow after flow, isochronal or modified isochronal, with
or without an extended stabilized flow. Transient IPRs
are also available. Shape factor and average pressure
can be calculated for closed and constant pressure
systems. IPR facilities are shared with Amethyste and
can be transferred between these modules on a single
Minifrac analysis (new in v4.20)
A consistent workflow combines the G-function plot
with derivatives to define the leakoff behavior and the
closure pressure. It is complemented by square root
and after closure analysis plots.
Slug and Pulse
A welcome return after a long break, this was
recently restored in v4.20. The processing allows
a modified version of the Ramey function to match
the slug pressure response of a DST with Bourdet
derivative type-curves. This method can also solve
for instantaneous production with wellbore storage.
This temporary, free Saphir NL component will be
removed in Generation 5 when a dedicated module
will be commercially available. This option enables
the interpretation of any number of probes, active
and interference, to discriminate vertical permeability.
Models for packer-probe and probe-probe interference
are included with the latter considering storage and
skin. An inbuilt preprocessor handles LAS format files
and calculates rates from pump volumes.
Reporting and exporting
Saphir has an extensive range of comparison,
reporting, exporting and printing capabilities. The
free and unprotected Saphir Reader allows files to
be read, printed and exported without the requirement
for an active license. A ‘slide presentation format’ is
available to use Saphir ‘live’ on a LCD projector or to
create PowerPoint™ slides.