Pre-Conference Short Course 2
30 July 2016
Who Should Attend
This course will be entirely comprehensible and useful for any exploration geologist who is interested in maturity or other aspects of source rocks. It will also be useful for managers who will want to understand all the tools they could have in their toolbox. It is intended for all exploration geologists, regardless of experience with kinetics and is a fairly comprehensive treatment of the topic, particularly the applications to exploration.
Although source-rock kinetics have been widely used in basin modeling for more than 25 years, recent technical developments have greatly increased the utility of kinetics data. Source-rock kinetics can now be used for a variety of purposes not imagined only a few years ago. These new applications are extremely valuable in both conventional and unconventional exploration.
Traditional methods of measuring kinetics were slow and expensive. A new method increases the speed of laboratory analysis by a factor of approximately 20, resulting in major reductions in cost and in acquisition time. In addition, kinetics can now be determined at even lower cost for samples for which appropriate archived Rock-Eval or Source-Rock-Analyzer data are available. Studies can even be carried out using a combination of archived and newly generated pyrolysis data. The use of archived data can greatly relieve the burden of acquiring samples where acquisition is expensive, difficult or impossible. Finally, the kinetics obtained by the new method are more reliable and have less chance of being significantly in error than kinetics determined by the traditional method.
Kinetic data includes the mean activation energy (Mean Ea) and the shape of the activation-energy distribution, but can also include a split of the hydrocarbons into liquid and gas products. Mean Ea values are conceptually similar to Tmax values, in that they are both derived from the Rock-Eval S2 peak, but are superior in that they take into account the entire S2 curve rather than simply the maximum. Kinetic data are normally used in conjunction with TOC and Rock-Eval data, as well as with other types of geochemical data, such as biomarkers. Kinetic data can also be integrated into sequence-stratigraphic interpretations.
The lower cost of kinetics data strongly encourages acquisition of large data bases of kinetics. These data bases can then be used not only to provide more-reliable kinetics for basin modeling (the traditional applications), but also to identify distinct organofacies within a single source layer and as a direct indicator of the progress of hydrocarbon generation. Source-rock kinetics can be easily linked to Transformation Ratio and vitrinite reflectance (Ro) values via relationships that are uniquely calibrated for each kerogen.
Exploration applications include:
- Defining distinct organofacies within a single source layer, showing both vertical and horizontal variation and thus permitting high-grading of a kitchen area according to kerogen quality
- Mapping Ro values calculated from the kinetic data to aid in calibrating thermal history in basin models.
- Mapping Transformation Ratios to indicate the actual progress of hydrocarbon generation across an area of interest.
Kinetic data can supplement Ro data where Ro data are available and confident, or they can replace Ro data where vitrinite is absent or where Ro measurements are unreliable (e.g., Ro suppression, Lower Paleozoic rocks where vitrinite is absent, carbonates where vitrinite is scarce or absent).
Specific applications to conventional exploration include defining source-rock facies and the hydrocarbon kitchen, with a view to later integrating this information with a migration scenario. Applications in unconventional exploration are somewhat different: since little or no migration is anticipated, one must know precisely where the kitchen is. Mean Ea is extremely valuable in precisely identifying kitchens. Criteria for defining a kitchen can be adjusted to meet specific exploration needs, such as the requirement of having oil with high GOR and high API gravity.