I believe our final reports should be complete and include all our assumptions and interpretations so that any future reviewers will at least be able to understand the bases for our conclusions. In addition, we provide soft copies of the Lumped EOS in formats which can be used with most reservoir simulation software.

A typical report on a complete project would include several main sections as follows:

Review of Historical PVT Data.

The review of each existing PVT study is documented. The summary includes details of the sampling and analysis companies, pertinent reservoir and well test data at the time of sampling and our conclusions (confidence levels) as to whether the samples and data are representative of the initial in place fluids.

The summary is followed with an in-depth review of the well conditioning and sampling processes. This is followed by an appraisal of the fluid compositions including an examination of the equilibrium ratios where applicable. A detailed EOS is largely predictive for most reservoir fluids including those with significant concentrations of non-hydrocarbon components. At this stage, we enter the composition into a detailed (say 30 component) EOS. We use various techniques, where necessary, to extend dated C7+ compositions. A detailed review of the PVT data is performed which includes material balance calculations, consistency checks and comparisons between reported and predicted PVT data. Fluid viscosity is one of the more important fluid properties; unfortunately, it is not possible to evaluate the accuracy of the reported data using material balance checks and comparisons with data from other tests. Therefore, special attention needs to be paid to assessing the accuracy of reported viscosity data especially as error bars on reported values can be very significant.

Review of Current PVT Data.

A similar report to that outlined above is generated for each contemporary PVT study. The Molecular Weight and Density of the heavier pseudo components are used to calculate many of the EOS parameters. In addition, modern analytical techniques enable fluid compositions to be reported beyond C7+. For these reasons, recommendations will be made during the planning stage to include some more detailed compositional measurements. Where appropriate, the above are used to extend some of the older fluid compositions and to correct those which have been calculated using inappropriate molecular weights.

As mentioned previously, error bars on reported viscosity data can be considerable. Unfortunately, our reviews of recent viscosity data indicate that the potential error bars on reported data from modern equipment has increased. Again, particular attention needs to be given to reducing the error bars on this important property.

Overview.

These days, it is generally recognised that PVT properties are dependent upon the actual fluid composition. Therefore, in this section, particular attention is paid to examining the reported qualified compositions from the different studies to identify potential aerial and vertical variations in fluid properties. Comparisons of Watson Characterisation Factors are useful for identifying erroneous data or compartmentalisation in the formations of interest.

Lumped EOS Specification.

This section contains a hard copy of the EOS specification. Soft copies are provided for use with the compositional reservoir simulator.

Validation of Lumped EOS.

The comparison of qualified, reported PVT data with predicted values from the lumped EOS is documented in this section. Where applicable, comparisons are also included for EOR and Asphaltene Precipitation studies.