Dataset Information

Gelation Kinetics of Hydrogels Based on Acrylamide?AMPS?NVP Terpolymer, Bentonite, and Polyethylenimine for Conformance Control of Oil Reservoirs.

ABSTRACT: Relatively smaller volumes of gelling systems had been used to address conformance problems located near the wellbore in oil reservoirs with harsh temperature and salinity conditions. These gelling systems were formulated with high concentrations of low-molecular-weight acrylamide-based polymers crosslinked with polyethylenimine (PEI). However, for in-depth conformance control, in which large gelant volumes and long gelation times were required, lower-base polymer loadings were necessary to ensure the economic feasibility of the treatment. In this study, a gelling system with high-molecular weight 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N-vinyl-2-pyrrolidone (NVP), acrylamide terpolymer, and PEI, with the addition of bentonite as a filler, was formulated. The influence of the gelant formulation and reservoir conditions on the gelation kinetics and final gel strength of the system was investigated through bottle tests and rheological tests. The addition of clay in the formulation increased the gelation time, thermal stability, and syneresis resistance, and slightly improved the final gel strength. Furthermore, samples prepared with polymer and PEI concentrations below 1 wt %, natural bentonite, and PEI with molecular weight of 70,000 kg/kmol and pH of 11: (i) presented good injectivity and propagation parameters (pseudoplastic behavior and viscosity ~25 mPa·s); (ii) showed suitable gelation times for near wellbore (~5 h) or far wellbore (~21 h) treatments; and (iii) formed strong composite hydrogels (equilibrium complex modulus ~10?20 Pa and Sydansk code G to H) with low syneresis and good long-term stability (~3 to 6 months) under harsh conditions. Therefore, the use of high-molecular-weight base polymer and low-cost clay as active filler seems promising to improve the cost-effectiveness of gelling systems for in-depth conformance treatments under harsh conditions of temperature and salinity/hardness.

SUBMITTER: Tessarolli FGC

PROVIDER: S-EPMC6473600 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature

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Gelation Kinetics of Hydrogels Based on Acrylamide⁻AMPS⁻NVP Terpolymer, Bentonite, and Polyethylenimine for Conformance Control of Oil Reservoirs.

Tessarolli Fernanda G C FGC Souza Sara T S STS Gomes Ailton S AS Mansur Claudia R E CRE

Gels (Basel, Switzerland) 20190214 1

Relatively smaller volumes of gelling systems had been used to address conformance problems located near the wellbore in oil reservoirs with harsh temperature and salinity conditions. These gelling systems were formulated with high concentrations of low-molecular-weight acrylamide-based polymers crosslinked with polyethylenimine (PEI). However, for in-depth conformance control, in which large gelant volumes and long gelation times were required, lower-base polymer loadings were necessary to ensu ...[more]

PMID: 30769870

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Project description:In this study, we explored the effective capture of both cations and anions onto a single adsorbent. Acrylamide (AAm) served as the polymer backbone, onto which co-monomers sodium p-styrenesulfonate (SS) and N,N-dimethylaminopropyl acrylamide (DMAPAA) were grafted, creating ionized polymer hydrogel adsorbents. These adsorbents were engineered for the synergistic separation and recovery of heavy metal cations and anions from concentrated solutions, focusing specifically on industrially significant ions such as Ni2+-, Cu2+, Zn2+ and (Cr2O7)2-. The adsorption and desorption behaviors of the AAm terpolymer hydrogels were investigated across various pH solutions, considering the competition and concentrations of these specific metal ions. Moreover, the study delved into the effects of the internal pH environment within the hydrogel adsorbents, determining its impact on the type of metal adsorbed and the adsorption capacity. Our findings indicated that the adsorption of cations was enhanced with a higher proportion of SS relative to DMAPAA in the hydrogel. In contrast, significant anion capture occurred when the concentration of DMAPAA exceeded that of SS. However, equal ratios of SS and DMAPAA led to a noticeable reduction in the adsorption of both types of substrates, attributed to the counteractive nature of these co-monomers. To enhance the adsorption efficiency, it may be necessary to consider methods for micro-scale separation of the two types of monomers. Additionally, the adsorption capacity was observed to be directly proportional to the swelling capacity of the hydrogels. For complete desorption and separation of the cations and anions from the adsorbent, the application of concentrated NaOH solutions followed by HNO3 was found to be essential. Given the varying concentrations of cation and anion pollutants, often present in heavy metal factory effluents, it is crucial to fine-tune the ratios of DMAPAA and SS during the synthesis process. This adjustment ensures optimized efficiency in the decontamination and recovery of these significant heavy metal ions.

Project description:Excessive water production from natural gas reservoirs is a main challenge facing the industry nowadays. Polymeric gelants have been widely applied to seal the water production zones, leading to a more feasible production operation. Nevertheless, conventional treatments fail in reservoirs characterized with the presence of sour gases. In this paper, aluminum-based salts are investigated as potential replacement for the conventional chromium acetate as crosslinkers for polyacrylamide (PAM), where aluminum has the advantage of being more environment-friendly besides its abundance. The investigation covers the whole pH range and examines the rheological behavior of the mature gels in the temperature range between 25 and 100 °C. While chromium acetate was proven to be sensitive to the presence of sour gases, namely, CO2 and H2S, because of the inability to produce a stable gel at the acidic conditions, this paper presents aluminum-based crosslinkers that are more tolerable toward high acidity. Unlike the conventional crosslinkers, the gelation rate in aluminum acetate and aluminum aminoacetate systems was found to decrease with the increase in pH. Both the crosslinkers succeeded in producing a strong gel with a storage modulus of more than 2000 Pa. Moreover, this study relates the physical stability of the colloidal aluminum crosslinkers with the viscoelastic behavior of the mature gel. The results reveal that aluminum acetate, among the screened salts, has a controllable gelation time at pH conditions between 3.5 and 8.5 and is the most stable in the temperature range 25-100 °C. PAM/AlAc system has a gelation time of around 50 min at 75 °C making it suitable for near-wellbore treatments, while the gelation time increased to 80 min upon increasing the pH of the system from 4.1 to 4.6. Moreover, the system showed good stability in saline conditions with NaCl concentration of up to 50,000 ppm. Scanning electron microscopy of freeze-dried samples proved the uniform distribution of colloidal crosslinkers and showed sheets wrapping around the colloidal particles. The performance of the new crosslinker is compared with available commercial crosslinkers.

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Dataset Information

Gelation Kinetics of Hydrogels Based on Acrylamide?AMPS?NVP Terpolymer, Bentonite, and Polyethylenimine for Conformance Control of Oil Reservoirs.

Publications

Gelation Kinetics of Hydrogels Based on Acrylamide⁻AMPS⁻NVP Terpolymer, Bentonite, and Polyethylenimine for Conformance Control of Oil Reservoirs.

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