Production logging is now seen as a powerful quantitative method that takes its own place in the set of data acquisition tools for the reservoir engineer, along side transient and production analysis. No longer just the tool of last resort, PL is now used as a calibration point for the reservoir model and as an important tool in the development over time of the producing intervals in the wellbore.

The interpretation process has shifted into the hands of the end-user engineer due, to a great extent, to the development of client, as opposed to tool focused software; Emeraude

Production logging surveillance has given the reservoir engineer a powerful tool in the drive for more accurate and refined reservoir characterization. Emeraude is now used by all the major service companies and all the major producers and many independent operators and service providers. Emeraude is seen as the industry standard allowing a common platform for communication and interpretation between service companies and operators.

From vertical injectors, to horizontal or highly deviated multiphase producers, Emeraude provides a comprehensive and intuitive set of tools, to produce results from the log data from simple through to the most sophisticated tool strings. A major new release v2.60 is scheduled for 2010 that will offer a choice of multiprobe workflows.

Emeraude is currently a stand-alone application that will migrate to the Ecrin environment under Generation 5.

Emeraude can load data from LIS, LAS, and ASCII files or from the clipboard or keyboard. Versus depth logs or stationary data can be input. Automatic tracks give an instant view of the log data while manual options allow users to customize their own views. A well sketch can be built, by drag-and-drop, with predefined elements and displayed alongside the data. Well views can be created from the browser to display the well geometry. Holdup channels can be added to the well view and plotted within the wellbore. All display settings can be customized and templates can be created.

An Emeraude document can contain an unlimited number of surveys and interpretations within these surveys. Emeraude offers a hierarchical representation in a data browser simultaneously showing all opened documents in a drag-and-drop environment. The browser contains a wide range of editing options: including lateral average, depth stretch, shift, data cut and fill, merging, splicing, derivative and sampling. The editing options can be enriched by connecting user functions through an external DLL API or by the recent addition of a built-in user formula module.

The user interactively defines the spinner calibration zones and the positive and negative lines on each zone are automatically calculated. Using a comprehensive tool kit for editing, and once the spinner calibration is satisfactory, the user generates an apparent velocity channel.

Several spinners can be handled simultaneously in the same interpretation, providing a simple facility to combine, for example, an in-line and fullbore spinner.

The PVT model defined by correlations provides the properties of any phase at any temperature and pressure. It is also possible to redefine the properties for each inflow zone. Correlations can be viewed both graphically and inside a table, and matched to user-entered data.

Rate calculation is treated as a minimization problem and solved using nonlinear regression, offering full flexibility in the type and number of input measurements. Interpretations can be run from any number of sufficient inputs including: spinner apparent velocity, density, pressure gradient, capacitance, holdup of any phase, velocity of any phase, rate of any phase, and temperature. Recent additions permit multiple measurement of the same type.

The default calculation scheme in Emeraude involves successively solving the cumulative rates at selected depths inside the wellbore. The contributions of the inflow zones, located in between the calculation zones, are then obtained from successive differences. Because each local regression is done regardless of the solution above or below, the overall solution may result in contributions from the same interval showing different signs which, physically, is not possible.

Global regression provides a method for solving these cases. For every producing interval, the sign of the contribution can be imposed. It is also possible to fix any particular contribution to a user-entered value, in particular a null value. Global regression can be coupled with a genetic algorithm to avoid local traps.

Emeraude offers a full range of flow models from single to 3-phase flow. Specific models are provided to handle flow re-circulation as well and standing water columns.

3 and 2-phase liquid-liquid stratified models for horizontal and highly deviated wells are available. It is also possible to connect user models through an external DLL interface.

Emeraude includes specific treatment for the Schlumberger DEFT, GHOST, and FSI and the Sondex MAPS suite; CAT, SAT and RAT tools. Image tracks can be created, and cross sections displayed at any depth. Average values of velocity, holdup, and, where relevant, phase velocity can be calculated using the arithmetic or stratified average.

Clean formation, shaly - single water and, shaly - dual water models are available. Channels required for the calculation can be loaded from an openhole interpretation, or estimated from correlations. Classical crossplots can be created to obtain or correct estimates. Time-lapse presentation can be obtained automatically by supplying the interpretation with additional water saturations, and defining the relevant chronology.

Selective Inflow Performance (SIP) can be made very quickly from the existing interpretations once the reservoir zones are defined. For gas rates, the SIP can be based on pseudopressure instead of pressure. 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 IPR. The SIP can use the total rate, the rate of a given phase, or the total liquid rate. The analysis can be done downhole or with surface values. Pressure datum correction can be applied and a composite IPR displayed.

The temperature model is analytical; it comprises an enthalpy balance opposite inflow zones, and a conduction/ convection model between. Joule-Thomson effects in the reservoir are accounted for given a user estimate of the relevant pressure drop. This process permits the analysis of Distributed Temperature (DTS) data, standalone temperature logs or can be used to replace a faulty spinner or a spinner ‘blinded’ by such effects as flow recirculation.

This allows the loading of reservoir pressure and reservoir permeability/mobility. Each depth point can be assigned a legend, and a quality indicator. All information appears on the tracks built automatically to display the pressure and permeability. Lines can be calculated or drawn and gradients/contacts are deduced.

A well sketch can be built interactively by drag-and-drop selecting from a library of completion components. Well views can be created from the deviation and internal diameter data and holdups displayed inside the view. In complex geometries the simultaneous display of the well view with the logs helps in understanding the nature of the flow.

All tool responses can be forward modeled given any particular flow scenario. The simulated channels take into account the tool specific response as well as their accuracy and noise.

Channels present in an Emeraude document can be exported in LIS, LAS, or ASCII format. The log output in Emeraude is WYSIWYG. Single or multiple log tracks, as well as any X-Y plot can be copied to the clipboard in Bitmap or WMF format. The log printout includes a preview option where fonts, scales and grid lines can be modified. Screen captures can be made at any point and returned to with a single click. API logs can be produced from the print preview option and stored within the document. 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.