Online Journal for E&P Geoscientists

John, Cedric M.^*1; Davis, Simon ¹; Jourdan, Anne-Lise ¹
(1) Earth Science and Engineering, Imperial College London, London, United Kingdom.

Diagenesis plays a major role in controlling the petrophysical properties of carbonate reservoirs, and improved subsurface predictions of petrophysics must therefore rely on a greater understanding of the geological processes of diagenesis. A fundamental parameter in diagenesis is the temperature at which diagenetic transformations occur: given a known geothermal gradient and burial history, and assuming that the diagenetic fluid is in thermal equilibrium with the formation, the temperature of precipitation of carbonate cements can be translated into depth and timing of the event. Comparing the relative timing of diagenetic transformations and of oil and gas migration has important implications for prospectivity.

The carbonate research team at Imperial College has been working in the framework of the Qatar Carbonate and Carbon Storage Research Centre (QCCSRC) at developing a new industry-standard approach to measuring temperature of precipitation of carbonate minerals in reservoir units. This method based on the laws of thermodynamics is called “clumped isotopes”, and it offers a number of advantages over traditional techniques: it is accurate to within a few degrees, can be applied to any diagenetic phases (unlike fluid inclusions) and does not require prior knowledge of subsurface fluid history.

This presentation will give an overview of the business relevance of clumped isotopes. In particular, we will focus on the need for calibrations at reservoir condition and the automation of the technique for oil and gas R&D and reservoir analysis. We will present the technical details of a new system called the IBEX (Isotopologues Batch EXtraction), an automated system for clumped isotope analysis. The IBEX was developed to facilitate the routine application of clumped isotopes as part of an integrated reservoir characterization workflow. The IBEX is currently in its testing phase and is a state-of-the-art system. We will show the first data generated on the IBEX using both standard materials and geological samples from reservoir analogue outcrops from Oman. This will serve as a demonstration of the promises that clumped isotopes hold for reservoir characterisation.

We would like to acknowledge that the QCCSRC is funded jointly by Qatar Petroleum, Shell and the Qatar Science & Technology Park.