Rip van Winkle

Rip van Winkle is a fictional character who had slept through the American Revolutionary War and discovered shocking change when he woke up. He later realized that he had been asleep for at least twenty years, based on data acquired from other villagers.

Rip van Winkle

Radiometric dating of geological events was a pivotal achievement (Holmes, 1911). Dating petroleum charge times, oil residence times and charge rate in a trap would be equally pivotal and eliminate, at a stroke, much arm-waving, geopoetry and speculation concerning charging times and routes. Charge times and rates are key variables in controlling hydrocarbon prospectivity as they define volumes of trapped petroleum and the dynamics of trap integrity, including leakage phenomena. Such constraints would allow for basin scale prospectivity estimates based on assessment of fraction of total basin charge trapped and more realistic assessment of regional caprock efficiencies when only limited cored cap rock material is available. This would also be an important parameter in the assessment of undersampled caprocks associated with potential CO2 storage sites for CCS, fracking fluid containment and alternative carbon storage vectors.

Schematic illustration of fluid fluxes in and out of a reservoir and the resulting residence time profile

Schematic illustration of fluid fluxes in and out of a reservoir and the resulting residence time profile

Yet, a practical method for dating petroleum field charging time from analysis of reservoired fluids does not exist. While forward basin models can provide estimates of charging times, they are unconstrained by any time-dependent measurements that can be made on the fluids and errors are large. The reality is that current solutions are totally non-unique and, in the absence of true validation data of source rock contributions and oil charge times, could have errors as large as order of magnitude level. The Re-Os method (Selby and Creaser, 2005) looks interesting, but the location of metals and exchange between fluids and solids in the system is not well defined and mechanisms for how an internal radiometric clock can track oil charge or residence time remain quite uncertain. The most robust dating methods must involve oil components that do not exchange with reservoir media!

During the RvW Project Phase II, we discovered how nuclear radiation in reservoirs impacts oil composition. From that, we saw how feasible it was to develop in situ gamma ray radiolysis proxies (RvW’s, in our parlance), such as the petroleum radiolysis products described by Frolov et al. (1998), as a means of assessing oil and gas residence time profiles in reservoirs. The first paper in a series of publications based on the RvW approach can be found at https://doi.org/10.1016/j.gca.2019.07.020. This preliminary paper sets out the geochemical landscape and constraints on radiation-based age dating proxies. Such an approach, in principle, may be capable of providing the first reliable oil charge dates available. The current RvW Project Phase III builds on a six-year journey in which several major discoveries have been made. At PRG, we are now well into the development and testing of a deployable reservoir oil residence age dating tool.

Industry Partnership Opportunities

Contact Steve Larter (slarter@ucalgary.ca) or Renzo C. Silva (rcsilva@ucalgary.ca)


References

Steve Larter, Renzo C. Silva, Norka Marcano, Lloyd R. Snowdon, Eduardo Villarreal-Barajas, Roshanak Sonei, Lydia C. Paredes Gutiérrez, Haiping Huang, Andrew Stopford, Thomas B.P. Oldenburg, Jing Zhao, Priyanthi Weerawardhena, Michael Nightingale, Bernhard Mayer, Jon H. Pedersen, Rolando di Primio. (2019) The dating of petroleum fluid residence time in subsurface reservoirs. Part 1: A radiolysis-based geochemical toolbox. Geochimica et Cosmochimica Acta, 261, 305-326.

Renzo C. Silva, Lloyd R. Snowdon, Haiping Huang, Michael Nightingale, Veith Becker, Stephen Taylor, Bernhard Mayer, Jon H. Pedersen, Rolando di Primio, Steve Larter. (2019) Radiolysis as a source of 13C depleted natural gases in the geosphere. Organic Geochemistry, 138. 

Marcano, N., Villarreal-Barajas, J.E., Oldenburg, T.B.P, Snowdon, L., Sonei, R., Huang, H., Weerawardhena, P., Briscoe, M., Silva, R.C., Song, F., Paredes Gutierrez, L., Larter, S.R. (2015) The dating of fluid residence time in petroleum and CO2 storage reservoirs. Part 1: Challenges and a design schematic for a practical geochemical toolbox. IMOG 2015, Prague – Czech Republic.

Selby, D. and Creaser, R.A. (2005) Direct radiometric dating of hydrocarbon deposits using rhenium-osmium isotopes. Science, 308, 1293-1295.

Frolov, E.B., Smirnov, M.B., Melikhov, V.A. and Vanyukova, N.A. (1998) Olefins of radiogenic origin in crude oils. Organic Geochemistry, 29, 409-420.

Holmes, A. (1911) The association of lead with uranium in rock minerals and its application to the measurement of geological time, Proc. Royal Society, Ser. A, 85, 248-256.