The project TeSCAL will use advanced mass spectrometric techniques at SINTEF and the University of Eastern Finland to develop protocols that can reduce uncertainty in special core analysis (SCAL) data. SCAL encompasses laboratory tests on petroleum reservoir rock (drilling cores) and fluids to determine key reservoir engineering properties. The most basic property at the pore scale is the wettability of the reservoir rock with respect to the reservoir fluids (oil, water, and gas). This largely controls the mobility of the reservoir fluids in the pore spaces and thus affects the oil production process.
Ideally, reservoir core samples should retain their original wettability when delivered for SCAL analysis. However, significant uncertainty often exists. Wettability is largely determined by minority oil components adsorbed onto the pore walls and these adsorbates can be spuriously altered during core retrieval from the reservoir. Therefore, common practice involves cleaning all reservoir fluids and drilling mud residues from samples using various solvents, followed by attempting to restore the original wettability through controlled re-exposure of the cleaned cores to oil from the reservoir. To determine if the original wettability can be restored this way, we will compare the mass spectrometric profile of oil components extracted from pore surfaces in core samples with that of oil produced from the reservoir. The mass spectrometric techniques will determine the molecular weight of individual oil components with sufficient resolution to identify the elemental formula of each compound. Comparing the profiles of adsorbed hydrocarbons and mobile oil can indicate whether the observed wettability of a reservoir core represents original conditions or is influenced by core treatment prior to SCAL analysis.
More reliable laboratory data can lead to better operational decisions, less risk of failed investments and better chances of optimisation, both in terms of extracted oil volume and energy use.