Polymer-Enhanced Low-Salinity Brine to Control In Situ Mixing and Salt Dispersion in Low-Salinity Waterflooding

Sarvestani, Arman Darvish; Rostami, Behzad; Mahani, Hassan

doi:10.1021/acs.energyfuels.1c00871

Cited by 18 publications

(23 citation statements)

References 46 publications

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“…The injection of ion-engineered water, or low salinity water as it is popularly referred to, has gained acceptance in the industry. Several works of literature [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ] exist on oil recovery improvement due to ion-tuned water injection, with several mechanisms identified to be responsible for the observed recovery. This section examines the effect of ion-tuned water on the surface charge development of the particles under study.…”

Section: Resultsmentioning

confidence: 99%

Effect of Native Reservoir State and Oilfield Operations on Clay Mineral Surface Chemistry

et al. 2022

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An understanding of clay mineral surface chemistry is becoming critical as deeper levels of control of reservoir rock wettability via fluid–solid interactions are sought. Reservoir rock is composed of many minerals that contact the crude oil and control the wetting state of the rock. Clay minerals are one of the minerals present in reservoir rock, with a high surface area and cation exchange capacity. This is a first-of-its-kind study that presents zeta potential measurements and insights into the surface charge development process of clay minerals (chlorite, illite, kaolinite, and montmorillonite) in a native reservoir environment. Presented in this study as well is the effect of fluid salinity, composition, and oilfield operations on clay mineral surface charge development. Experimental results show that the surface charge of clay minerals is controlled by electrostatic and electrophilic interactions as well as the electrical double layer. Results from this study showed that clay minerals are negatively charged in formation brines as well as in deionized water, except in the case of chlorite, which is positively charged in formation water. In addition, a negative surface charge results from oilfield operations, except for operations at a high alkaline pH range of 10–13. Furthermore, a reduction in the concentrations of Na, Mg, Ca, and bicarbonate ions does not reverse the surface charge of the clay minerals; however, an increase in sulfate ion concentration does. Established in this study as well, is a good correlation between the zeta potential value of the clay minerals and contact angle, as an increase in fluid salinity results in a reduction of the negative charge magnitude and an increase in contact angle from 63 to 102 degree in the case of chlorite. Lastly, findings from this study provide vital information that would enhance the understanding of the role of clay minerals in the improvement of oil recovery.

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Section: Resultsmentioning

confidence: 99%

Effect of Native Reservoir State and Oilfield Operations on Clay Mineral Surface Chemistry

et al. 2022

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“…The salt dispersion, which happens when LSW mixes with high-salinity water, is one of the downsides of LSW flooding; however, new research suggests that by adding around 200 ppm polymer, the salt dispersion can be decreased by roughly 70%, resulting in a lower volume of LSW usage. 82 Also, with so many research articles emphasizing the benefits of increased SO 4 2– concentration on oil recovery, no attention has been paid to the potential damage it can cause due to sulfate-based scale precipitation, which can result in wettability alterations and permeability damage. Thus, as stated in the preceding section, this research is aimed at understanding the effect of sulfate-based scales on the calcite mineral surface charge and the consequent wettability state.…”

Section: Smart and Low Salinity Watermentioning

confidence: 99%

“…As robust as the research on LSW and smart water is and their implications on oil recovery, it is not without a drawback, which includes sulfate scale precipitation and salt dispersion. The salt dispersion, which happens when LSW mixes with high-salinity water, is one of the downsides of LSW flooding; however, new research suggests that by adding around 200 ppm polymer, the salt dispersion can be decreased by roughly 70%, resulting in a lower volume of LSW usage . Also, with so many research articles emphasizing the benefits of increased SO 4 2– concentration on oil recovery, no attention has been paid to the potential damage it can cause due to sulfate-based scale precipitation, which can result in wettability alterations and permeability damage.…”

Section: Smart and Low Salinity Watermentioning

confidence: 99%

Effect of Sulfate-Based Scales on Calcite Mineral Surface Chemistry: Insights from Zeta-Potential Experiments and Their Implications on Wettability

et al. 2022

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Scale formation and deposition in the subsurface and surface facilities have been recognized as a major cause of flow assurance issues in the oil and gas industry. Sulfate-based scales such as sulfates of calcium (anhydrite and gypsum) and barium (barite) are some of the commonly encountered scales during hydrocarbon production operations. Oilfield scales are a well-known flow assurance problem, which occurs mainly due to the mixing of incompatible brines. Researchers have largely focused on the rocks’ petrophysical property modifications (permeability and porosity damage) caused by scale precipitation and deposition. Little or no attention has been paid to their influence on the surface charge and wettability of calcite minerals. Thus, this study investigates the effect of anhydrite and barite scales’ presence on the calcite mineral surface charge and their propensity to alter the wetting state of calcite minerals. This was achieved vis-à-vis zeta-potential (ζ-potential) measurement. Furthermore, two modes of the scale control (slug and continuous injections) using ethylenediaminetetraacetic acid (EDTA) were examined to determine the optimal control strategy as well as the optimal inhibitor dosage. Results showed that the presence of anhydrite and barite scales in a calcite reservoir affects the colloidal stability of the system, thus posing a threat of precipitation, which would result in permeability and porosity damage. Also, the calcite mineral surface charge is affected by the presence of calcium and barium sulfate scales; however, the magnitude of change in the surface charge via ζ-potential measurement is insignificant to cause wettability alteration by the mineral scales. Slug and continuous injections of EDTA were implemented, with the optimal scale control strategy being the continuous injection of EDTA solutions. The optimal dosage of EDTA for anhydrite scale control is 5 and 1 wt % for the formation water and seawater environments, respectively. In the case of barite, in both environments, an EDTA dosage of 1 wt % suffices. Findings from this study not only further the understanding of the scale effects on calcite mineral systems but also provide critical insights into the potential of scale formation and their mechanisms of interactions for better injection planning and the development of a scale control strategy.

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“…Additional information regarding the materials used in this study and the viscosity of different polymer solutions versus shear rate can be found in our previous publication. 41 Because the only salt used to synthesize the polymer solutions was NaCl, there is no impact of water hardness on the rheology of the prepared solutions and PELS.…”

Section: Brine and Polymer Solutionsmentioning

confidence: 99%

“…The procedure of fabrication of the sandpack, injection protocol, and dispersivity estimation were exactly similar to that reported in our previous publication. 41 The sandpacks were cylindrical with the length and diameter of 25 and 3 cm, respectively. This ensures an effective one-dimensional (1D) flow in the porous medium.…”

Section: Brine and Polymer Solutionsmentioning

confidence: 99%

Impact of Injection Parameters on Mixing Control by Polymer-Enhanced Low-Salinity Waterflooding

2022

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In situ mixing by dispersive transport of salt and viscous fingering between the injected low-salinity (LS) brine and high-salinity (HS) formation brine can jeopardize the performance of low-salinity waterflooding (LSWF). In our previous papers, we demonstrated that in situ mixing can be suppressed by polymerenhanced low-salinity waterflooding (PELS), in which a small amount of a viscosifying agent, such as a polymer, is added to the LS stream. Nevertheless, effective mixing control with PELS depends upon several factors and operational conditions, whichhave not yet been addressed. Therefore, this research focuses on the investigation of the impact of injection parameters, such as the polymer concentration, salinity difference, and injection rate, on the performance of PELS. In this regard, single-phase mixing experiments were performed using synthetic sandstone cores (sandpacks). The experimental results reveal that adding only 200 ppm of hydrolyzed polyacrylamide polymer (HPAM) lowers the salt dispersivity by up to 84%, depending upon the salinity difference. The results indicate that higher LS injection rates intensify the salt dispersivity and weaken the performance of PELS as a result of the dependency of polymer solution viscosity upon the share rate. The dependency of dispersivity upon the injection rate increases as the salinity difference increases. On the basis of our experimental data, we developed an empirical model to predict the required pore volume of PELS to displace the resident HS brine in the core as a function of the salinity difference and injection rate. A mathematical model based on the advection−dispersion theory is also presented to calculate the required volume of PELS for consecutive brine injection or slug injection. The results of this paper highlight that PELS is an effective method to increase the performance of formation brine displacement during LSWF and tackle the negative impact of salt dispersion on LSWF, particularly at a large scale. These results are also of use in hydrogeology and contaminant remediation.

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Polymer-Enhanced Low-Salinity Brine to Control In Situ Mixing and Salt Dispersion in Low-Salinity Waterflooding

Cited by 18 publications

References 46 publications

Effect of Native Reservoir State and Oilfield Operations on Clay Mineral Surface Chemistry

Effect of Native Reservoir State and Oilfield Operations on Clay Mineral Surface Chemistry

Effect of Sulfate-Based Scales on Calcite Mineral Surface Chemistry: Insights from Zeta-Potential Experiments and Their Implications on Wettability

Impact of Injection Parameters on Mixing Control by Polymer-Enhanced Low-Salinity Waterflooding

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