Emulsified acid systems for oil well stimulation: A review

Adewunmi, Ahmad A.; Sølling, Theis I.; Sultan, Abdullah S.; Saikia, Tinku

doi:10.1016/j.petrol.2021.109569

Cited by 43 publications

(12 citation statements)

References 64 publications

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“…In this experiment, the biomolecule PC was expected to be used as a surface modifier to increase the affinity of the microspheres to cells, but it was insufficient to attenuate the toxicity of the microspheres in NIH-3T3 and L929 cells. This finding may be caused by the acid stimulation of paraffin oil through the oil phase of the microsphere emulsification preparation [ 25 , 26 ]. However, basic DAP used for microsphere modification attenuated paraffin-stimulated cytotoxicity.…”

Section: Resultsmentioning

confidence: 99%

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

Chang

Chen

et al. 2023

Polymers

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Hydrogel-based microspheres prepared by emulsification have been widely used as drug carriers, but biocompatibility remains a challenging issue. In this study, gelatin was used as the water phase, paraffin oil was used as the oil phase, and Span 80 was used as the surfactant. Microspheres were prepared using a water-in-oil (W/O) emulsification. Diammonium phosphate (DAP) or phosphatidylcholine (PC) were further used to improve the biocompatibility of post-crosslinked gelatin microspheres. The biocompatibility of DAP-modified microspheres (0.5–10 wt.%) was better than that of PC (5 wt.%). The microspheres soaked in phosphate-buffered saline (PBS) lasted up to 26 days before fully degrading. Based on microscopic observation, the microspheres were all spherical and hollow inside. The particle size distribution ranged from 19 μm to 22 μm in diameter. The drug release analysis showed that the antibiotic gentamicin loaded on the microspheres was released in a large amount within 2 h of soaking in PBS. It was stabilized until the amount of microspheres integrated was significantly reduced after soaking for 16 days and then released again to form a two-stage drug release curve. In vitro experiments showed that DAP-modified microspheres at concentrations less than 5 wt.% had no cytotoxicity. Antibiotic-impregnated and DAP-modified microspheres had good antibacterial effects against Staphylococcus aureus and Escherichia coli, but these drug-impregnated groups hinder the biocompatibility of hydrogel microspheres. The developed drug carrier can be combined with other biomaterial matrices to form a composite for delivering drugs directly to the affected area in the future to achieve local therapeutic effects and improve the bioavailability of drugs.

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Section: Resultsmentioning

confidence: 99%

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

Chang

Chen

et al. 2023

Polymers

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“… 23 − 25 These acid systems for the mechanism of inhibiting the reaction rate are mainly used in the first acid–rock reaction process by increasing the viscosity to reduce the transfer coefficient of H + . 26 − 28 …”

Section: Introductionmentioning

confidence: 99%

“…One of the most critical points in carbonate acidizing treatments is inhibiting the acid–rock reaction rate. Commonly, three steps are recognized in the acid–rock reaction process: hydrogen ions are delivered to the rock surface through mass transfer; hydrogen ions are involved in the reaction at the surface of the rock; and the products leave the rock surface and move into the liquid. , Some high-viscosity fluids, such as gelled acids, emulsified acids, and surfactant-based acids, have been developed to inhibit the acid–rock reaction rate. − These acid systems for the mechanism of inhibiting the reaction rate are mainly used in the first acid–rock reaction process by increasing the viscosity to reduce the transfer coefficient of H + . − …”

Section: Introductionmentioning

confidence: 99%

Ability to Inhibit H⁺ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca²⁺ Circumstances

et al. 2022

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To study the ability to inhibit ion transmission of the Gemini surfactant under different Ca 2+ circumstances, three kinds of Gemini surfactants with different alkyl chain lengths are synthesized (C n -4-C n , n = 12, 14, and 16), which are characterized using 1 H NMR, 13 C NMR, and Fourier transform infrared spectroscopy. To analyze the property of inhibition of the acid–rock reaction rate, surface tension and contact angle measurements and atomic force microscopy (AFM) results are obtained with different surfactants and under different Ca 2+ concentrations. Inhibition rates with different alkyl chain lengths and an acid-etched surface morphology are also studied carefully. The result shows that all cationic Gemini surfactants significantly impact the control of the reaction rate, and the reaction rate decreased remarkably by 44.4% after adding 12-4-12. The Δ G and W A indicate that 12-4-12 has the best adsorption ability on the rock with added Ca 2+ compared with the other two Gemini surfactants. It is revealed through the AFM that Ca 2+ can significantly change the adsorption morphology of the surfactant. The surfactant adsorption area decreased when Ca 2+ is dispersed in the solution as well. These two phenomena can lead to the reduced ability to block H + of 14-4-14 and 16-4-16. However, the presence of Ca 2+ affects the adsorption area of 12-4-12 slightly. Thus, the reaction rate, including that of 12-4-12, is almost unchanged. Because 12-4-12 is adsorbed tightly on the rock surface, H + can only react with the rock on the unabsorbed dot, resulting in rock surface nonuniformity after being etched, which is beneficial for maintaining the conductivity of the crack.

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“…However, it is less likely to discover new large oil and gas fields every year. Therefore, to effectively utilize limited resources, especially to improve the recovery more effectively for existing oil and gas fields, acidizing is a frequent and routine measure for oil and gas field plug removal and stimulation. − As a typical or basic feature of oil and gas reservoirs, heterogeneity brings about a poor acidizing effect or even failure . Especially for a water flooding reservoir, with long-term high-intensity water injection, the heterogeneity of the reservoir will be further aggravated. − To improve the acidizing effect, not only should the type and volume of acid be optimized but diverting technology should also be used to ensure that the acid is injected into the whole interval or more into the low-permeability (seriously damaged) interval …”

Section: Introductionmentioning

confidence: 99%

“…Therefore, to effectively utilize limited resources, especially to improve the recovery more effectively for existing oil and gas fields, acidizing is a frequent and routine measure for oil and gas field plug removal and stimulation. 2 − 5 As a typical or basic feature of oil and gas reservoirs, heterogeneity brings about a poor acidizing effect or even failure. 6 Especially for a water flooding reservoir, with long-term high-intensity water injection, the heterogeneity of the reservoir will be further aggravated.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

Liu

Lan

et al. 2022

ACS Omega

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As a typical feature of a reservoir, heterogeneity is the main reason for low oil recovery and the poor effect of acidizing measures. Diversion is the main measure to improve the acidizing effect. Over the years, technological progress has mainly focused on the material development of diverting agents. In this study, the diverting effect and influencing factors for a viscous fluid were systematically studied by the heterogeneous dual-core flooding experiment. The results are as follows: First, increasing the displacement pressure in heterogeneous reservoirs can improve the diverting effect, which is consistent with maximum differential pressure and injection rate (MADPIR) theory, but the diverting effect is weak. The injection pressure difference is increased by 50 times, and the diverting effect is improved by 16.27% at most. Second, taking a viscous fluid as the stimulation fluid can partially realize the diversion for heterogeneous reservoir and further improve the acidizing effect, and the breaking through PV can be improved by 78% at most. Using a viscous fluid as a diverting agent can achieve 100% balanced acid injection. Third, compared with a viscoelastic surfactant, a relatively uniform and stable polymer solution as the diverting agent has the possibility to completely block the low-permeability layer. So, a 5% viscoelastic surfactant as the diverting agent is more suitable for acidizing. Finally, any diverter injected into the formation will enter all layers. The conclusion that the diverting agent only enters the high-permeability layer but not the low-permeability layer is not tenable. Diverting acidizing is only effective for near-well zones, which is difficult to fundamentally solve the seepage problem of heterogeneous reservoirs.

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Emulsified acid systems for oil well stimulation: A review

Cited by 43 publications

References 64 publications

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

Ability to Inhibit H⁺ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca²⁺ Circumstances

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

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Emulsified acid systems for oil well stimulation: A review

Cited by 43 publications

References 64 publications

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

In Vitro Characterizations of Post-Crosslinked Gelatin-Based Microspheres Modified by Phosphatidylcholine or Diammonium Phosphate as Antibiotic Delivery Vehicles

Ability to Inhibit H+ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca2+ Circumstances

Experimental Study on the Diversion Characteristic of a Viscous Fluid in a Heterogeneous Reservoir

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Ability to Inhibit H⁺ Transmission of Gemini Surfactants with Different Chain Lengths under Different Ca²⁺ Circumstances