Low Salinity Flooding in a Selected Carbonate Reservoir: Experimental Approach

Al-Attar, Hazim; Mahmoud, M. Y.; Zekri, Abdulrazag Y.; Almehaideb, Reyadh A.; Ghannam, Mamdouh T.

doi:10.2118/164788-ms

Cited by 36 publications

(21 citation statements)

References 21 publications

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“…At the 69.7 ppm Sulphate concentration, the opposite effect was observed for the contact angle, again consistent with coreflood data. Al-Attar et al (2013) study indicates that an increasing Sulphate concentration, alters the wettability to an intermediate wetting state, which contributes to the incremental oil recovery. Wettability alteration and incremental oil recovery is observed up to an optimal Sulphate concentration.…”

Section: −mentioning

confidence: 89%

“…There is no significant increase of recovery when seawater is diluted to 5000 ppm. However there are no experiments performed by Al-Attar et al (2013) with diluted seawater below 5000 ppm, while this might be the salinity boundary for LSF in carbonates.…”

Section: Wettability Alteration Due To Ion Exchangementioning

confidence: 99%

“…According to Al-Attar et al (2013), increasing the Calcium concentration in a low salinity brine has a negative effect on the oil recovery. However, the effect of Calcium together with Sulphate on the oil recovery was not tested by Al-Attar et al (2013).…”

Section: −mentioning

confidence: 99%

“…However, the effect of Calcium together with Sulphate on the oil recovery was not tested by Al-Attar et al (2013).…”

Section: −mentioning

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: 89%

Section: Wettability Alteration Due To Ion Exchangementioning

confidence: 99%

Section: −mentioning

confidence: 99%

“…However, the effect of Calcium together with Sulphate on the oil recovery was not tested by Al-Attar et al (2013).…”

Section: −mentioning

confidence: 99%

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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Study on Optimum Time to Start Water Injection in Porous Low-Permeability Carbonate Reservoir

Lu,

Cheng,

Chen

2023

Springer Series in Geomechanics and Geoengineering

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Application of Low-Salinity Waterflooding in Carbonate Cores: A Geochemical Modeling Study

et al. 2020

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Waterflooding is the most widely applied improved oil recovery technique. Recently, there has been growing interest in the chemistry and ionic composition of the injected water. Low-salinity waterflooding (LSWF) is a relatively recent enhanced oil recovery technique that has the ability to alter the crude oil/brine/rock interactions and improve oil recovery in both clastics and carbonates. In this paper, the increase in the recovery factor during LSWF was modeled based on the exchange of divalent cations (Ca2+ and Mg2+) between the aqueous phase and the carbonate rock surface. Numerical simulations were performed using laboratory coreflood data, and oil recovery and pressure drop from experimental works were successfully history matched. The ion exchange equivalent fractions, effluent ions concentrations, changes in mineral moles, and pH have also been examined. Besides, an investigation of multi-component ionic exchange as a mechanism responsible for wettability alteration during LSWF in heterogeneous low-permeability carbonate cores is presented. The results show that wettability alteration is responsible for the increase in oil recovery during LSWF, as reflected by the shift in the crossover points of the relative permeability curves. A sensitivity study done on many key parameters (e.g., timing of LSWF injection, injection rate and temperature) and the mechanistic modeling method revealed that they all have huge effects on the process.

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Low Salinity Flooding in a Selected Carbonate Reservoir: Experimental Approach

Cited by 36 publications

References 21 publications

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Calcite Dissolution Behaviour During Low Salinity Water Flooding in Carbonate Rock

Study on Optimum Time to Start Water Injection in Porous Low-Permeability Carbonate Reservoir

Application of Low-Salinity Waterflooding in Carbonate Cores: A Geochemical Modeling Study

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