Charging behaviour at the carbonate rock‐water interface in low‐salinity waterflooding: Estimation of zeta potential in high‐salinity brines

2021 ◽  
Author(s):  
Navpreet Singh ◽  
Paras H. Gopani ◽  
Hemanta K. Sarma ◽  
Padmaja Mattey ◽  
Digambar S. Negi ◽  
...  
Keyword(s):  
Zeta Potential ◽  
Carbonate Rock ◽  
High Salinity ◽  
Water Interface ◽  
Low Salinity ◽  
Low Salinity Waterflooding

scholarly journals Low salinity waterflooding EOR laboratory test using a carbonate rock

2016 ◽  
Vol 81 (6) ◽  
pp. 489-494
Author(s):  
Takaaki Uetani ◽  
Katsumo Takabayashi ◽  
Hiromi Kaido ◽  
Hideharu Yonebayashi
Keyword(s):  
Laboratory Test ◽  
Carbonate Rock ◽  
Low Salinity ◽  
Low Salinity Waterflooding

Pore-Scale Imaging of Tertiary Low Salinity Waterflooding in a Heterogeneous Carbonate Rock at Reservoir Conditions

2021 ◽  
Author(s):  
Ahmed M. Selem ◽  
Nicolas Agenet ◽  
Martin J. Blunt ◽  
Branko Bijeljic
Keyword(s):  
High Resolution ◽  
Capillary Pressure ◽  
Oil Recovery ◽  
High Salinity ◽  
Wettability Alteration ◽  
Micro Ct ◽  
Pore Scale ◽  
Low Salinity ◽  
Low Salinity Waterflooding ◽  
Fluid Configuration

Abstract We investigated pore-scale oil displacement and rock wettability in tertiary low salinity waterflooding (LSW) in a heterogeneous carbonate sample using high-resolution three-dimensional imaging. This enabled the underlying mechanisms of the low salinity effect (LSE) to be observed and quantified in terms of changes in wettability and pore-scale fluid configuration, while also measuring the overall effect on recovery. The results were compared to the behavior under high salinity waterflooding (HSW). To achieve the wetting state found in oil reservoirs, an Estaillades limestone core sample was aged at 11 MPa and 80°C for threeweeks. The moderately oil-wet sample was then injected with high salinity brine (HSB) at a range of increasing flow rates, namely at 1, 2,4, 11, 22 and 42 µL/min with 10 pore volumes injected at each rate.Subsequently, low salinity brine (LSB) was injected following the same procedure. X-ray micro-computed tomography (micro-CT) was usedto visualize the fluid configuration in the pore space.A total of eight micro-CT images, with a resolution of 2.3 µm/voxel, wereacquired after both low salinity and high salinity floods.These high-resolution images were used to monitor fluid configuration in the porespace and obtain fluid saturations and occupancy maps. Wettabilitywascharacterized by measurements of in situ contactanglesand curvatures. The results show that the pore-scale mechanisms of improved recovery in LSW are consistent with the development of water micro-dropletswithin the oil and the expansion of thin water films between the oil and rock surface. Before waterflooding and during HSW, the measured contact angles were constant and above 110°, while the meancurvature and the capillary pressure values remained negative, suggesting that the HSB did not change the wettability state of the rock. However, with LSW the capillary pressure increased towards positive values as the wettability shifted towards a mixed-wet state. The fluidoccupancy analysis reveals a salinity-induced change in fluid configuration in the pore space. HSB invaded mainly the larger pores and throats, but with LSW brine invaded small-size pores and throats.Overall,our analysis shows that a change from a weakly oil-wet towards a mixed-wet state was observed mainly after LSW, leading to an incremental increase in oil recovery. This work established a combined coreflooding and imaging methodology to investigate pore-scale mechanisms and wettability alteration for tertiary LSW in carbonates.It improves our understanding of LSW asan enhanced oil recovery (EOR) method for potential field-scale applications. The data provides a valuable benchmark for pore-scale modelling as well as an insight into how even modest wettability changes can lead to additional oil recovery.

scholarly journals A Synergy between Controlled Salinity Brine and Biosurfactant Flooding for Improved Oil Recovery: An Experimental Investigation Based on Zeta Potential and Interfacial Tension Measurements

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Tinuola Udoh ◽  
Jan Vinogradov
Keyword(s):  
Zeta Potential ◽  
Interfacial Tension ◽  
Crude Oil ◽  
Oil Recovery ◽  
High Salinity ◽  
Improved Oil Recovery ◽  
Low Salinity ◽  
All Solutions ◽  
Rock Interface ◽  
Incremental Oil Recovery

In this study, we have investigated the effects of brine and biosurfactant compositions on crude-oil-rock-brine interactions, interfacial tension, zeta potential, and oil recovery. The results of this study show that reduced brine salinity does not cause significant change in IFT. However, addition of biosurfactants to both high and low salinity brines resulted in IFT reduction. Also, experimental results suggest that the zeta potential of high salinity formation brine-rock interface is positive, but oil-brine interface was found to be negatively charged for all solutions used in the study. When controlled salinity brine (CSB) with low salinity and CSB with biosurfactants were injected, both the oil-brine and rock-brine interfaces become negatively charged resulting in increased water-wetness and, hence, improved oil recovery. Addition of biosurfactants to CSB further increased electric double layer expansion which invariably resulted in increased electrostatic repulsion between rock-brine and oil-brine interfaces, but the corresponding incremental oil recovery was small compared with injection of low salinity brine alone. Moreover, we found that the effective zeta potential of crude oil-brine-rock systems is correlated with IFT. The results of this study are relevant to enhanced oil recovery in which controlled salinity waterflooding can be combined with injection of biosurfactants to improve oil recovery.

scholarly journals Pore-scale imaging and analysis of low salinity waterflooding in a heterogeneous carbonate rock at reservoir conditions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmed M. Selem ◽  
Nicolas Agenet ◽  
Ying Gao ◽  
Ali Q. Raeini ◽  
Martin J. Blunt ◽  
...  
Keyword(s):  
Oil Recovery ◽  
Carbonate Rock ◽  
Pore Space ◽  
Contact Angles ◽  
Fluid Distribution ◽  
Pore Scale ◽  
Low Salinity ◽  
Low Salinity Waterflooding ◽  
Capillary Pressures ◽  
Micro Tomography

AbstractX-ray micro-tomography combined with a high-pressure high-temperature flow apparatus and advanced image analysis techniques were used to image and study fluid distribution, wetting states and oil recovery during low salinity waterflooding (LSW) in a complex carbonate rock at subsurface conditions. The sample, aged with crude oil, was flooded with low salinity brine with a series of increasing flow rates, eventually recovering 85% of the oil initially in place in the resolved porosity. The pore and throat occupancy analysis revealed a change in fluid distribution in the pore space for different injection rates. Low salinity brine initially invaded large pores, consistent with displacement in an oil-wet rock. However, as more brine was injected, a redistribution of fluids was observed; smaller pores and throats were invaded by brine and the displaced oil moved into larger pore elements. Furthermore, in situ contact angles and curvatures of oil–brine interfaces were measured to characterize wettability changes within the pore space and calculate capillary pressure. Contact angles, mean curvatures and capillary pressures all showed a shift from weakly oil-wet towards a mixed-wet state as more pore volumes of low salinity brine were injected into the sample. Overall, this study establishes a methodology to characterize and quantify wettability changes at the pore scale which appears to be the dominant mechanism for oil recovery by LSW.

Double-Layer Expansion: Is It a Primary Mechanism of Improved Oil Recovery by Low-Salinity Waterflooding?

2014 ◽  
Vol 17 (01) ◽  
pp. 49-59 ◽  
Author(s):  
Ramez A. Nasralla ◽  
Hisham A. Nasr-El-Din
Keyword(s):  
Double Layer ◽  
Oil Recovery ◽  
High Salinity ◽  
Improved Oil Recovery ◽  
Low Salinity ◽  
Ph Values ◽  
Low Salinity Water ◽  
Primary Mechanism ◽  
Low Salinity Waterflooding ◽  
Salinity Water

Summary Literature review shows that improved oil recovery (IOR) by low-salinity waterflooding could be attributed to several mechanisms, such as sweep-efficiency improvement, interfacial-tension (IFT) reduction, multicomponent ionic exchange, and electrical-double-layer (EDL) expansion. Although these mechanisms might contribute to IOR by low-salinity water, they may not be the primary mechanism. Therefore, the main objective of this study is to investigate if the mechanism of EDL expansion could be the principal reason for IOR during low-salinity waterflooding. Low-salinity water results in a thicker EDL when compared to high-salinity water, so we tried to eliminate the effect of low-salinity brines on double-layer expansion to show to what extent IOR is related to EDL expansion caused by low-salinity water. The double-layer expansion is dependent on the electric surface charge, which is a function of the pH of brine; therefore, the pH levels of low-salinity brines were decreased in this study to provide low-salinity brines that can produce a thinner EDL, similar to high-salinity brines. ζ-potential measurements were performed on both rock/brine and oil/brine interfaces to demonstrate the effect of brine pH and salinity on EDL. Contact angle and coreflood experiments were conducted to test different brine salinities at different pH values, which could assess the effect of water salinity and pH on rock wettability and oil recovery, and hence involvement of EDL expansion in the IOR process. ζ-potential results in this study showed that decreasing the pH of low-salinity brines makes the electrical charges at both oil/brine and brine/rock interfaces slightly negative, which reduces the double-layer expansion caused by low-salinity brine. As a result, the rock becomes more oil-wet, which was confirmed by contact-angle measurements. Moreover, coreflood experiments indicated that injecting low-salinity brine at lower pH values recovered smaller amounts of oil when compared to the original pH because of the elimination of the low-salinity-water effect on the thickness of the double layer. In conclusion, this study demonstrates that expansion of the double layer is a dominant mechanism of oil-recovery improvement by low-salinity waterflooding.

A Sensitivity Study on Low Salinity Waterflooding

2017 ◽  
Vol 04 (03) ◽  
pp. 231-236 ◽  
Author(s):  
Barham S. Mahmood ◽  
Jagar Ali ◽  
Shirzad B. Nazhat ◽  
David Devlin
Keyword(s):  
Sensitivity Study ◽  
Low Salinity ◽  
Low Salinity Waterflooding
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