Improving Waterflood Recovery Efficiency in Carbonate Reservoirs through Salinity Variations and Ionic Exchanges: A Promising Low-Cost "Smart-Waterflood" Approach

Zhang, Yi; Sarma, Hemanta Kumar

doi:10.2118/161631-ms

Cited by 104 publications

(64 citation statements)

References 46 publications

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“…So the incremental oil recovery as a result of LSF is very sensitive to the temperature [Zhang and Sarma 2012]. Secondly, the pressure drop along the core is larger for higher temperatures, which is explained by the Zhang and Sarma (2012) as an effect of mineral dissolution which creates blockage of pore throats and fiercer brine/rock interaction.…”

Section: −mentioning

confidence: 99%

“…Wettability alteration and incremental oil recovery is observed up to an optimal Sulphate concentration. Zhang and Sarma (2012) performed LSF coreflood experiments in tertiary mode in carbonate reservoir cores with a length of 7.5-9.3 cm and a diameter of 3.8 cm. In the secondary mode seawater was injected till the residual oil S or was reached, in order to see clearly the LSF effect.…”

Section: −mentioning

confidence: 99%

“…The stabilized pressure slightly increased with decreasing salinity, while viscous forces should decrease with decreasing salinity. According to Zhang and Sarma (2012), the pressure build up was accompanied with the incremental oil production. The total incremental oil production at 70…”

Section: −mentioning

confidence: 99%

“…These clay particles are lacking in Carbonate porous media. The suggested recovery mechanism for carbonates is wettability alteration [Aladasani et al 2012;Yousef et al 2011], due to ion exchange [Al Shalabi et al 2013;Brady et al 2012], electric double layer expansion [Alotaibi et al 2011], Calcite dissolution [Hio 2008;Yousef et al 2011;Zhang and Sarma 2012] and pH increase. Other mechanisms are insitu surfactants generation, emulsion formation [Emadi and Sohrabi 2013;Mahzari and Sohrabi 2014], salting-in effect [RezaeiDoust et al 2009] and fines migration [Zahid et al 2012].…”

Section: Introductionmentioning

confidence: 99%

“…Wettability alteration from oil wet to intermediatewater wet is proven to be the main contributor to the incremental oil recovery when the salinity of the injection fluid is lowered. The presence of Sulphate in the brine have been proven to be a wettability modifier in several studies [Hognesen et al 2005;Al-Attar et al 2013;Zhang and Sarma 2012;Zhang et al 2007]. …”

Section: Introductionmentioning

confidence: 99%

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Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Ouden¹,

Nasralla²,

Guo³

et al. 2015

Proceedings

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Master of ScienceCalcite dissolution behaviour during low salinity water flooding in carbonate rockby Liselotte den OudenLow salinity water flooding (LSF) has been proved to be a promising enhanced oil recovery method for sandstone reservoirs. The efficiency of LSF in carbonate reservoirs has not been proven completely yet, because there are still uncertainties about the LSF recovery mechanism in carbonate. From experimental studies, it was shown that wettability alteration, due to salinity reduction, is able to mobilize the remaining oil. Some studies attributed the wettability alteration by LSF to Calcite dissolution. Furthermore, Calcite dissolution can influence the salinity and pH of injected brines, and hence the oil recovery.However, there is a lack of experimental data on the Calcite dissolution effect of LSF in carbonate rock.The objective of this experimental study was to get a better understanding of the Calcite dissolution behaviour and how it might affect the oil recovery. Bulk and coreflood experiments have been performed; the experimental data was history matched with the use of PHREEQC. Calcite dissolution decreased with decreasing P CO2 and increased with decreasing pH and increasing NaCl salinity from 500-2000PPM.Increasing the injection rate reduced the interaction time and therefore Calcite dissolution did not reach equilibrium in coreflood at high rates. Calcite dissolution from chalk matched with the Calcite dissolution from pure Calcite, while Calcium concentration in effluent from limestone was higher. The two-phase coreflood experiment confirmed that Calcite dissolution occurs as well if oil is present in the porous media, but showed lower values than in single-phase coreflood experiment. pH increased from 5-6 to 9.5 due to Calcite dissolution, which might have an effect on the rock and oil surface charges, and hence oil recovery improvement. The effluent of the two-phase coreflood showed that an emulsion was formed, which suggested formation of in-situ surfactants. From CT scans, micro-CT scans and material mass balance calculations an increase in porosity around 1% was observed. The increase in the total dissolved species due to Calcite dissolution was not significant, which will not harm LSF effect.

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Section: −mentioning

confidence: 99%

Section: −mentioning

confidence: 99%

Section: −mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Ouden¹,

Nasralla²,

Guo³

et al. 2015

Proceedings

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An Analytical Solution to Interpret Active Ion Transport During Chemically‐Tuned Waterflooding Process in High‐Temperature Carbonate Rocks

Awolayo

Sarma

2018

Can J Chem Eng

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Recent studies on carbonate reservoirs suggest that modifying the injected brine chemistry leads to a competition amongst ions at the rock surface sites, causing alteration in the rock wettability. As such, the potential increase in oil recovery heavily relies on the relationship between the ion transport and chemical reaction. In this work, we highlighted the three processes that govern this relationship as advection by fluid transport, hydrodynamic dispersion resulting in spreading, and sorption of the ions to the rock. An analytical solution to the mathematical equations describing solute reactive transport was derived based on the advection‐reaction‐dispersion equation (ARDE). Our model was first used to replicate produced ion histories from single phase experiments to emphasize the impact of the active ions on rock surface sites. We then studied the movement of the active ions by predicting the breakthrough composition of different ions during oil‐brine displacement experiments and evaluated the impact of the transport and reaction parameters on the wettability change. The wettability change profile was captured in terms of the sorbed ion concentration, where a high retardation was observed for the active ions. The observed oil recoveries in a data set of two‐phase experiments were correlated to the resultant effect of the rock surface chemistry. This study highlights the importance of rock surface chemistry on wettability change and oil production from carbonate rocks.

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Mechanistic study of the carbonated smart water in carbonate reservoirs

2021

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Carbonated smart water (CSMW) injection has drawn considerable interest, especially in the last decade. This interest stems from its results in the recovery factor enhancement and the storage of carbon dioxide. This method has been mainly studied for sandstone formations, and less devotion has been given to carbonates, especially in naturally fractured reservoirs. This paper examines the effect of the CSMW on the recovery factor in carbonate homogenous and fractured reservoirs and investigates the most effective mechanisms. Furthermore, the capability of the CSMW to store the CO 2 in the reservoir has been tested. This work has been established based on core flooding experimental data, using a compositional simulator, and extending the core results to a pilot model. The composition and salinity values of the CSMW have been specified using optimization and sensitivity analysis tools. Geochemical reactions and CO 2 solubility in the CSMW have been simulated using the PHREEQC. In the core scale, the CSMW showed 14, 7.6, 26.8% more oil recovery than Smart Water (SMW), Carbonated Seawater (CSW), and Seawater (SW), respectively. In the pilot model, CSMW recovered more oil than the SMW by 5-8% based on the heterogeneity and fracture availability. Viscosity reduction is one of the main mechanisms behind the oil recovery increment. More than 30% of viscosity reduction was observed for all studied cases. Ions exchange and mineral dissolution processes were also pivotal. A higher recovery has been obtained in the fractured reservoir after the breakthrough due to the CO 2 diffusion from the fractures into the matrices and the spontaneous imbibition process, where those mechanisms need a long time to act effectively. More than 50% of the injected CO 2 within the CSMW has been captured in the reservoir's residual oil and water. It has been concluded that the stored CO 2 in the reservoir depends on the amount of residual oil saturation, where the higher the remaining oil in the reservoir, the higher the stored CO 2 amount.

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Improving Waterflood Recovery Efficiency in Carbonate Reservoirs through Salinity Variations and Ionic Exchanges: A Promising Low-Cost "Smart-Waterflood" Approach

Cited by 104 publications

References 46 publications

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

An Analytical Solution to Interpret Active Ion Transport During Chemically‐Tuned Waterflooding Process in High‐Temperature Carbonate Rocks

Mechanistic study of the carbonated smart water in carbonate reservoirs

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