Chemical EOR
1. What exactly dictates the economic viability of a surfactant-aided chemical EOR - despite it's retention of surfactants through adsorption, precipitation, degradation & phase-trapping?
2. How exactly are we able to upscale - the observed physical/chemical processes associated with the ‘surfactant adsorption’ (van der Waals interactions between non-polar surfactant chains, hydrogen bonding, chemisorption, surface precipitation, electrostatic interaction, ion exchange, hydrophobic tail-solid interactions) from ‘sub-pore-scale’ to Darcy-scale?
Feasible to bridge the gap, if the cores are aged with crude oil in the presence of connate-water?
3. Feasible to quantify the magnitude of adsorbed surfactants as a function of formation brine-composition, reservoir rock-type and its mineralogical composition, pH & salinity of in-situ and injected fluid phases, surface-redox potential and the fundamental chemical structure of the injected surfactants?
4. What is the fraction of ‘total adsorbed surfactants’ that tend to get desorbed as a function of time (sorption kinetics)?
Does it depend on ‘surface wettability’ and ‘redox state’ of the used cores?
5. How do we ensure whether the rate at which surfactants get adsorbed remain the same - throughout the surfactant-aided chemical EOR treatment?
6. How about the desorption of surfactants?
Whether, do we have a correlation between surfactant adsorption and desorption rates?
7. Under what circumstances, are we supposed to expect
(a) non-equilibrium adsorption?;
(b) non-linear adsorption?; &
(c) sorption kinetics of the surfactants
associated with the surfactant-aided chemical EOR?
8. To what extent, are we able to restore a sandstone core from an oxidized- to a reduced-state towards replicating anaerobic reservoir conditions @ lab-scale in the absence of impacting core-mineralogy and pore-structure?
Feasible to quantify the reduction in surfactant adsorption in cores under anaerobic conditions - resulting from oxide removal and calcite dissolution?
9. Considering reservoir surface hydrophobicity as a function of time, how about the natural correlation between ‘the oil or water-wet surfaces of a sandstone/carbonate reservoir rock’ and ‘the adsorption of surfactants’?
10. How about the rate of wettability alterations for a sandstone and a carbonate reservoir?
11. How exactly the ‘specific surface area’ and the ‘adsorption density per unit surface area’ gets altered in a typical sandstone and carbonate reservoirs – resulting from wettability treatment of cores at the laboratory-scale – before and after reaching CMC?
12. Whether the observed ‘arrival time of surfactant front’ @ lab-scale would match with the field-scale scenario?
13. To what extent, the observed results on the surfactant concentration @ lab-scale reflect the real field scenario, particularly, following the surfactant breakthrough?
Regarding the rate of wetting of sandstone, I do not know a special licensed methodology, but I would proceed from the principle of logic: 1) I took several samples of different weights (volumes), the more, the better; 2) Dried according to the standard method; 3) placed in a chamber saturated with water vapor (100%), possibly a desiccator; 4) periodically weighed at certain intervals until the weight stabilized; 5) plotted graphs based on measurement data; 6) calculated the wetting rate
You are facing a very difficult problem! In a multicomponent (polygenic) rock (without destruction), only physical and hydrophysical parameters can be studied. To study physical and chemical processes, it is necessary to decompose the rock into separate mineral and organomineral formations and study each separately, and then, most likely, model. But I foresee that the model will not give high accuracy.