A word on Multiple Probe Tools
Recent years have seen a step change in the
complexity of wells with multiple zones, phases and
deviation ranging from vertical to horizontal. This has
led to the development of esoteric logging tools with
multiple arrays attempting to describe the complex
and constantly varying flow regimes. Masses of
data are created that needs visualization, QA/QC
and analysis. It is not a straightforward process. It
is easy to succumb to the temptation of a ‘black box’
that will do some clever statistical stuff and generate
what looks like a perfectly acceptable analysis
when presented in PowerPoint™. Looks pretty but
it could lead to fantastically expensive errors when
misguided well interventions are made. Production
log interpretation is not rate measurement. The key to
the process is in the name: Interpretation. Engineers
interpret, machines do not. The engineer must control
the software not the other way around.
Data load and display
Emeraude can load logs and stationary data from
LIS, LAS, and ASCII files. Automatic tracks are built to
give an instant view of the log data while customized
views can be created. A well sketch can be built by
completion component drag-and-drop. All display
settings can be customized and templates created.
Data structure, browser, and editing
The hierarchical Emeraude documents contain an
unlimited number of surveys and interpretations. The
Emeraude browser contains a wide range of editing
options: lateral average, depth stretch, shift, data cut
and fill, merging, splicing, derivative, sampling, userformula
module, additional functions through external
DLL’s. Stations can be displayed vs. time.
Spinner calibration and apparent velocity
Multiple spinners can be handled simultaneously, in
particular for multi-probe tools. Various calibrations
and editing may be performed on user defined spinner
calibration zones. Apparent velocity channels are then
calculated for each pass and each spinner.
Single and zoned PVT
Emeraude black-oil PVT offers a wide choice of
correlations which can be viewed and matched to
user-defined measurements. Tables may also be
loaded. If the PVT is zoned, properties are redefined
for each inflow zone. A steam-water model is available
to analyze steam injection wells.
Regression in Zoned / Continuous analysis
Rate calculation is treated as an optimization problem
using nonlinear regression, with full flexibility in the
type and number of input measurements, as long
as they are in sufficient number: apparent velocity,
density, pressure gradient, capacitance, phase
holdup, phase velocity, phase rate, temperature, etc.
Calculations may be zoned or continuous. The zoned
calculation focuses on user defined intervals. The
continuous method seeks agreement everywhere on
the logs, and the holdups are treated as variables,
allowing a possible deviation from the slip model.
The zoned method works well most of the time and
it is very fast. The continuous method may provide a
better answer in complex cases and when attempting
to match the temperature. The user has the choice.
Local vs. global regression
The local regression in the zoned method calculates
cumulative rates on selected intervals. This may also
be the starting point for the continuous method, where
a global regression solves for the contributions of the
inflow intervals. Such a global regression solves for
the entire well at once using user-defined constraints
such as the contribution sense, surface rates, etc. It
is also possible to fix any particular contribution to a
fixed or null value.
Emeraude offers a complete range of flow models
from single to 3-phase. Specific models are provided
to handle flow re-circulation and standing water
columns. Three and two-phase liquid-liquid stratified
models for horizontal and highly deviated wells are
available. It is possible to connect user models through
an external DLL interface.
Multiple Probe Tool (MPT) processing
Emeraude includes a specific treatment for the
Schlumberger PFCS, GHOST, and FSI, and the
Sondex MAPS suite: the CAT, SAT and RAT tools.
Image views are created and cross sections displayed
at any depth and for any combination of passes. A
process fits the discrete measurements with relevant
2D models, contingent to user-defined constraints on
segregation, phase presence or other tools. The output
can be presented for QA/QC, and results compared
with the raw data. Average values of phase holdups,
mixture velocity, and phase rates are produced and
serve as input to the interpretation.
Pulsed Neutron Log (PNL) interpretation
Clean formation and shaly single / dual water
models are available. Channels may be estimated
from correlations or loaded from other openhole
interpretations. Classical crossplots can be created to
obtain or correct estimates. Time-lapse presentation
can be generated.
Selective Inflow Performance (SIP)
SIP can be made with a few clicks. Pseudopressures
are used for gas. An unlimited number of SIP’s can be
created and compared. Each zone can be assigned a
different model: straight line, c&n, or Jones. The SIP
can use the total rate, a phase rate, or the total liquid
rate. Data may be downhole or from surface. Pressure
datum correction and composite IPR’s are available.
Temperature models and DTS
Emeraude offers a segmented model and an energy
model. The analytical segmented model accounts
for enthalpy balance in front of inflow zones, and
conduction / convection in-between. Joule-Thomson
effects are calculated from a user estimated pressure
drop. The numerical energy model solves the full
energy equation in the wellbore and the reservoir,
accounting explicitly for the thermal effects within the
reservoir. Both models can be used for the analysis of
DTS data, standalone temperature logs, or to replace
a faulty or blinded spinner.
Tool responses can be modeled for any particular flow
scenario. The simulated channels take into account
the tool specific response, its resolution and the noise.
Packer leaks and steam injection can be simulated.
Formation test data QAQC
Reservoir pressure, permeability and mobility may be
loaded. Quality indicators can be added at any depth.
Lines can be calculated or drawn, gradients and fluid
contacts can be calculated.
This method corrects, with the PL interpretation,
the open-hole effective permeability. It uses an IPR
relationship where the relevant reservoir or perforation
parameters are defined zone by zone. The method is
implemented for single-phase liquid, liquid mixture, or
for gas using pseudopressures.
This special analysis uses a dedicated 2-phase steamwater
PVT for the design of steam-injection tests. The
temperature, pressure, holdup, and velocity profiles
are calculated from surface, to come up with the
property of the injected fluid in each zone. Relevant
slip models are considered.
Output / Export
Emeraude log channels can be exported in LIS, LAS, or
ASCII format. Log tracks and X-Y plots can be copied
to the clipboard as a bitmap or a Windows Metafile.
Fonts, scales and grid lines can be modified. API logs
can be produced. A built-in report can be printed and
previewed that includes predefined sections. It is
possible to produce a report in MS-Word™ using the
OLE™ interface of Emeraude. A template MS-Word™
report is installed and can be customized as required.
All reporting and exporting features are accessible
with the free Emeraude reader.