Desktop data

By Joe Jacquot

Seismic derived rock properties are frequently under-used by oil and gas asset teams because the tools to properly interpret them and incorporate the results into the standard workflow have been seen and sold as “specialist tools”. Joe Jacquot discusses how, with the advent of Microsoft Windows-based technology from Fugro-Jason, asset teams can now fully realise the value of their seismic data.

To get the most out of a field, reservoir engineers rely on 3D models that identify the reservoir location and the properties of the rocks within. The Achilles heel of these models has been their almost total reliance on well-based data. While providing great insight into the zones encountered by the wells, the models can only extrapolate that insight into zones away from wells.

For some time now, high quality, laterally extensive elastic rock property models and reservoir properties derived from them have been available through seismic inversion. These models, however, have largely remained unavailable to, or under-used by, asset team geoscientists, remaining instead within specialist teams. Often they are only used for enhancing seismic interpretation.

Perhaps the greatest factor limiting utilisation of the rock property data within the asset team has been the lack of software tools on the geoscientist's typical desktop platform - the Windows PC. That limitation has now been removed and what was once only for the specialist is now available to every geoscientist with the release of JasonSTS software for asset teams. Designed specifically for Windows, the tools properly handle the data types involved, enabling interpretation to be done in a more meaningful way, and allowing easy incorporation of results into the geologic model.

Rock property cubes are the output of a process that essentially conditions and integrates the seismic and well data. For this process to be robust, a single consistent wavelet should be present in the seismic data. The estimation process ties the seismic data to well log data, determines the waveforms present in the data, accounts for lateral and vertical variability, and helps to determine if corrective measures are necessary. Once the seismic is corrected, rock property cubes have to be accurately generated and made available for analysis in conjunction with the geologic model.

With these new tools, the geoscientist is able to tie new wells to the seismic data in these models with great accuracy and apply 3D body checking to the (multiple) property models to identify specific elastically derived reservoir lithologies. Crossplots and histograms reveal the lithotypes and their separation in elastic property space.

Bayesian Inference can be employed to determine the probability for each lithotype from the multiple property volumes. The results can either be visualised as individual lithotype probabilities, allowing for an assessment of risk, or a most-likely lithotype cube generated by sampling individual probability cubes.

Bodies and properties can then be exported directly to a geological model, ensuring that all properties are correctly transformed into the appropriate geological zone. This results in a more accurate and realistic geological model, incorporating spatially extensive properties and/or bodies from seismic data and not relying purely on interpolation of well-measured properties.

Productive reservoir components can be mapped along with a net pay map for the main pay intervals. Tracks can be created to predict drilling results from pseudo wells. Body checking relies on deterministic rock property relationships and is much faster than traditional line and trace picking.

Armed with the new geological model, production engineers can craft a plan to extract the hydrocarbons most efficiently. Reservoir engineers can better assess the risks and potential for the field. Decisions such as how many wells to drill and where are backed by a more quantitative analysis of the field.

It is now easier than ever before to incorporate rock property cubes into geologic models by performing the entire analysis on Windows-based desktops and laptops. The combined model provides new quantitative insight that can significantly improve reservoir development. Rock properties on the geoscientist's desktop - the next big thing.

Biography

Joe Jacquot is Strategic Marketing Manager with Fugro-Jason, a leading provider of seismic inversion and reservoir characterisation products and services. He joined the company in 2005 as Marketing Manager in Houston and has 32 years' experience in the exploration, production, seismic and reservoir characterisation sectors of the industry with a number of oil companies, including Schlumberger and Fugro.