Work package 4
Work Package Title: Salt precipitation in packed beds of varying wettability in the presence of organic phases and surfactants
Duration: 36 Months
The aim of this WP is to obtain a quantitative approach of the phenomena taking place during salt precipitation in packed beds of homogeneous wettability (hydrophilic pore surfaces, hydrophobic pore surfaces) and of mixed wettability (coexistence of hydrophilic and hydrophobic pore surfaces) in the presence of organic phases and of surfactants.
Task 4.1 Salt precipitation in packed beds of varying wettability.
Calcium carbonate precipitation experiments will be performed in small size beds. The beds will be designed to have a diameter of 4-5mm and length less than 3cm in order to be used under a micro CT-Scan. The packing material of the beds will be hydrophilic microspheres (glass) and hydrophobic microspheres (PTFE). The experiments shall be performed in: a. water-wet (hydrophilic) beds (only glass microspheres will be used), b. oil-wet (hydrophobic) beds (only PTFE microspheres will be used), c. mixed –wet beds: glass and PTFE spheres will be packed at layers and d. mixed –wet beds where the glass and PTFE microspheres will be packed randomly at various fractions. The fluid systems shall include: a. only supersaturated solutions (blank experiments), b: supersaturated solutions in the presence of organic water-immiscible phase (n-dodecane) at initial oil saturation Soi=1.0 (i.e. oil-saturated column) and at Sor (i.e. residual oil saturation to waterflooding done on Soi=1.0), c: supersaturated solutions mixed with organic water-miscible substance (eg. MEG) at various concentrations and at Soi=0.0 (column saturated with aqueous phase), Soi=1.0 (i.e. oil-saturated column) and at Sor (i.e. residual oil saturation to waterflooding done on Soi=1.0) and d: supersaturated solutions mixed with surfactants at Soi=0.0, Soi=1.0 and at Sor. Two sets of these experiments shall run in parallel: one bed shall be used for micro CT-Scanning and one shall be used for solid characterization (XRD, SEM). Micro CT-Scanning is expected to provide information concerning salt concentration in relevance with the hydrophilic and hydrophobic pore surface areas of the bed. The ex-situ micro CT-Scanning will be conducted at IFP Energies Nouvelles S.A. (Rueil-Malmaison Cedex, France). The small liquid volumes to be used in this task, are not expected to provide accurate quantitative relations between the fractional wettability and the solid deposits formed but the information of the layout at the interior of the columns without disturbing the pore structure (and the structure of deposits) shall contribute significantly in understanding issues like the initiation and further progress of salt formation.
Task 4.2. Salt precipitation in packed beds of varying wettability: quantitative analyses.
This task is planned to guarantee the quantitative analysis of the phenomena and to reduce the risk of task 4.1. Within this task, similar experiments with these described in task 4.1 will be performed in large beds (at least 3cm diameter and 10cm length). The aim of the planned experiments is to obtain quantitative relations between the fractions of hydrophobic, hydrophilic areas, the total mass precipitated and the oil saturation of the bed or other parameters such as the concentration of surfactant, the concentration of organic water-miscible phase. The same sets of experiments with these described in Task 4.1 shall be carried out. During the experiments, pH at the outlet of the bed shall be monitored and total calcium concentration at the outlet shall be measured using AAS. At the end of the experiments, as already described, solids will be characterized by XRD and SEM. If needed quantitative methods of analysis for the simultaneous presence of calcium polymorphs and packing material shall be developed.