Adsorption of Polar Organic Components onto Sandstone Rock Minerals and Its Effect on Wettability and Enhanced Oil Recovery Potential by Smart Water

Abstract

It is generally accepted that reservoir wettability is one of the most important parameters in oil recovery processes. In the published literature, it is believed that the state of reservoir wettability mainly depends on the adsorption or precipitation of oxygen and nitrogen compounds present in the heavy-end fractions of crude oil. However, the establishment of reservoir wetting is a more complex process that involves chemical interactions between all phases of the reservoir: rock mineral surfaces, formation water, and surface-active components in the crude oil. In this study, dynamic adsorption tests were performed by flooding modified crude oils with a low asphaltene content through outcrop sandstone cores. Adsorption of crude oil components was analyzed by comparing base number (BN) and acid number (AN) of the effluent oil samples with the known initial BN and AN of the crude oil. The experimental results showed that crude oil bases are more active than acids toward the silicate rock mineral surfaces. Within the pore volumes flooded, it was not possible to achieve equilibrium BN values because of the continuous adsorption of basic components. Spontaneous imbibition (SI) tests showed that the core sample behaved slightly water-wet after crude oil flooding. Ion-modified smart water as an imbibition fluid in tertiary mode has previously shown potential for wettability alteration and improved oil recovery. With an increase in the amount of injected crude oil through the core, a decrease in oil recovery and a decrease in smart water-enhanced oil recovery (EOR) potential were observed. SI oil recovery results indicate reduced positive capillary forces and a change in wetting toward a less water-wet state. Thus, the chemical composition of crude oil should be considered as an important parameter for a reliable estimation of the reservoir wettability state and EOR potential by smart water injection.

The role of polar organic components in dynamic crude oil adsorption on sandstones and carbonates

“…A greater affinity of basic over acidic material has also been reported by dynamic adsorption tests performed by Mamonov et al (2019).…”

“…His studies confirmed that the acidic material in sandstones does not have the same affinity as in carbonates, and the basic material appears to have greater influence on the rock surface wettability than the acidic material [43].…”

“…The core T15 was restored by establishing S wi = 20% with FW T , followed by crude oil injection (10 PV) at 50° C, crude oil T had an AN=0.17 and BN=0.23 [43]. The development of the adsorption profiles is shown in Figures 14-15.…”

Numerical simulation of enhanced oil recovery studies for aqueous gemini surfactant‐polymer‐nanoparticle systems

“…Investigations in recent years have shown that adsorption/desorption forces existing among oil and rock particle in petroleum‐bearing formations exert a marked influence on the efficiency with which oil can be produced by water flooding 31‐33 . 2.5 times pore volume (PV) of crude oil was flooded into the core sample (within core‐holder) until the maximum volume of initially present brine/aqueous phase was extracted in the collecting tube, until irreducible water saturation is reached.…”

Effect of ionic strength in low salinity water injection processes

“…Conversely, this study concluded that wettability alteration by double-layer expansion and cation exchange represents the dominant microscopic mechanism in low salinity water injection. Mamonov [9], argues that, although in the literature wettability is one of the most important mechanisms, it depends on the adsorption of compounds from the heavy fractions of crude oil. It is complex to establish the reservoir's wettability as it implies chemical interaction with rock minerals, formation water, and surfactant compounds from crude oil.…”