Research project

Project fact sheet

Combined clumped isotope thermometry and modelling to understand unconventional reservoirs

Project researcher(s): 
Sarah Robinson
Project supervisor(s): 
Dr Cédric M. John
Project supervisor(s): 
Annabel Dale
Duration: 
November, 2018 - January, 2022
Funding

Unconventional resources, including shale gas and oil shale, present new challenges when it comes to understanding their depositional history and the history of burial and maturation. Many of the traditional geochemical proxies either cannot be used (fluid inclusions, too small to be measured in shales) or offer at best an approximation of the temperature/depth reached by the shales (e.g. stable isotope of oxygen, that depends on an assumption of the pore fluid oxygen isotope composition for a reasonable estimate of temperature. Here, we proposal a dual approach of a case study on core material or outcrop material containing shales of interest, and numerical modelling of the depositional history and thermal history of the shales.

The selection of the geological region of interest is still underway, but could include North American shales and other target of interest in Europe. Although it is the thermal history of the shales that is the main focus of this project, samples will be taken across a wide range of the stratigraphy to be able to reconstruct a coherent thermal history for the basin. Targets of particular interests are carbonate-rich shales (i.e. carbonate matrix) and carbonate-infill fractures within the shales. The thermal history will be reconstructed using clumped isotopes paleothermometry, a cutting edge technique that the lab at Imperial College London is equipped to handle.

 

The clumped isotope method is based on the grouping (or “clumping”) of the heavy isotopes of oxygen and carbon within the lattice of carbonate minerals, which has been demonstrated to be dependent on temperature only. Clumped isotopes can be used in any carbonate phase (crystalline or not) and is independent of fluid composition.

Here, we propose to combine the use of the clumped isotope paleothermometer, a tool that through the recrystallization of fine-grained sediments allows to track changes in temperatures, with numerical modelling. The modelling will be a forward stratigraphic model to understand various deposition parameters within the basin. This forward modelling will be done at a range of time and spacial scales, and will also be combined with numerical simulation of the thermal history of our unconventional basin.