Define Reference Channels
The reference channels will be used to compute the PVT properties and also in the regression during zone rates calculation.
In Emeraude, pressure temperature and any relevant hold-up or density channel need to be defined. If more than one pass is selected, a lateral average will be applied.
PL Tool Configuration
Density tool type needs to be defined to allow the relevant corrections are applied in the calculation scheme. The spinner blade diameter must be entered to compute the velocity profile correction factor. A built-in list of capacitance tools is included for the different vendors, with their respective calibration charts.
Spinner Calibration and Velocity Generation
The spinner measures revolutions per second (RPS), but the interpreter needs fluid velocity and rates. To transform spinner RPS and cable speed to fluid velocity, the spinner calibration parameters need to be known. When sufficient passes are available, an in-situ spinner calibration can be performed.
Different calibration modes and editing tools are available on user defined spinner calibration zones. The interpolation between calibration zones may be modified, depending on the fluid distribution in the pipe.
Once the spinner calibration parameters are known, the apparent velocity is calculated for each pass and each spinner, where applicable.
For MPT spinners, a Hold-up weighted spinner calibration option is offered to handle toolstring rotation in stratified flow conditions.
PL phase calculation is highly sensitive to the PVT. Consequently, when calculating the rates at downhole conditions, a number of PVT properties are required. Also, to convert the downhole rates to surface conditions, the volume factors need to be known.
Black-oil PVT offers a wide choice of correlations, which can be viewed and matched to user-defined measurements. PVT tables may also be loaded. If the PVT is zoned, properties are redefined for each inflow zone. A steam-water model is available to analyse steam injection wells.
In the presence of MPT sensors, an average value of holdup and rates is computed at every depth, from the discrete measurements.
At every depth, an average value of holdup and rates, from the distributed measurements, is computed.
The MPT processing first maps the measurements using 2D models and then integrates holdups and velocities to compute the rates. The mapping can be constrained by the user, by, for example, forcing stratification and accounting for conventional measurements.
N number of passes can be stacked (or combined) into a single equivalent ‘virtual’ pass, which contains N times the number of probes, compared to the original tool.
The rates are calculated in selected intervals of the log, and a continuous profile can be created.
Rate calculation is treated as an optimization problem using nonlinear regression, with full flexibility in the type and number of input measurements. Calculations may be zoned or continuous. The zoned calculation focuses on user defined stable flow intervals. The continuous method seeks agreement everywhere on the logs and the holdups are treated as variables, allowing a possible deviation from the slip models. 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 temperature. The user has the choice.
The global regression solves for the contribution of the inflow intervals instead of the selected calculation zones only. Such regression solves for the entire well at once, allowing the user to impose constraints such as the contribution sense, surface rates, etc. It is also possible to fix any particular contribution to a fixed or null value.
Log and Results
The interpretation’s result is presented in the form of a cumulative and contribution profiles with phase rates. This can be at downhole or standard conditions.
Numerical outputs can be obtained from the summary table, which shows the cumulative and contribution rates, and velocities of each phase, with the PVT properties at the level of each inflow zone