Live imaging of micro and macro wettability variations of carbonate oil reservoirs for enhanced oil recovery and CO2 trapping/storage

Abstract

Carbonate hydrocarbon reservoirs are considered as potential candidates for chemically enhanced oil recovery and for CO2 geological storage. However, investigation of one main controlling parameter—wettability—is usually performed by conventional integral methods at the core-scale. Moreover, literature reports show that wettability distribution may vary at the micro-scale due to the chemical heterogeneity of the reservoir and residing fluids. These differences may profoundly affect the derivation of other reservoir parameters such as relative permeability and capillary pressure, thus rendering subsequent simulations inaccurate. Here we developed an innovative approach by comparing the wettability distribution on carbonates at micro and macro-scale by combining live-imaging of controlled condensation experiments and X-ray mapping with sessile drop technique. The wettability was quantified by measuring the differences in contact angles before and after aging in palmitic, stearic and naphthenic acids. Furthermore, the influence of organic acids on wettability was examined at micro-scale, which revealed wetting heterogeneity of the surface (i.e., mixed wettability), while corresponding macro-scale measurements indicated hydrophobic wetting properties. The thickness of the adsorbed acid layer was determined, and it was correlated with the wetting properties. These findings bring into question the applicability of macro-scale data in reservoir modeling for enhanced oil recovery and geological storage of greenhouse gases.

Rock–Fluid Interactions of Alkyl Ether Carboxylate Surfactants with Carbonates: Wettability Alteration, ζ-Potential, and Adsorption

“…At least 10 drops of DI water were placed in random positions on the surface of each core plate, and the CA was measured after equilibration. The contact angle value was calculated as an average mean, and the standard deviation was determined. , …”

“…The contact angle value was calculated as an average mean, and the standard deviation was determined. 10,65 2.2.6. ζ-Potential Measurements. The methodology was developed based on Ding and Rahman 66 and Lara Orozco et al 67 To prepare a calcite suspension, 10 mL of brine/surfactant solution was placed into a 20 mL vial, and 0.1 g of rock powder was added.…”

“…3 Two main complications cause the low effectiveness of oil production in carbonates: first, the complex heterogeneous structure and pore network 7,9 and second, the complex wettability due to adsorbed polar components of oil such as resins, asphaltenes, and carboxylic acids. 4,10,11 The wettability in the reservoir determines the spreading of fluids and their relative permeabilities. The wetting fluid is distributed in small pores, while the nonwetting one has a tendency to occupy the larger pores making binding pathways.…”

“…However, the development of carbonates is associated with many difficulties, and as a result, the oil recovery factor is low and does not exceed 35%. , Thus, about 60% of liquid hydrocarbons (HC) remain unswept after implementing primary and secondary recovery techniques . Two main complications cause the low effectiveness of oil production in carbonates: first, the complex heterogeneous structure and pore network , and second, the complex wettability due to adsorbed polar components of oil such as resins, asphaltenes, and carboxylic acids. ,, …”

Chemical Enhanced Oil Recovery: Where Do We Stand? Recent Advances and Applications

“…Furthermore, in [38], it was shown that the wettability of carbonates measured by a common laboratory method (contact angle) that differs from wettability measured in corresponding areas of the surface at the microlevel. As such, results demonstrated that wettability at the microlevel was mixed (i.e., hydrophilic and hydrophobic zones) while at the macrolevel surface showed only hydrophobic wetting preferences.…”