Delayed Crosslink Polymer Gel System for Water Shutoff in Conventional and Unconventional Oil and Gas Reservoirs

Jayakumar, Swathika; Lane, Robert H.

doi:10.2118/164046-ms

Cited by 24 publications

(10 citation statements)

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“…As reported in the literature, some delayed crosslinked gel systems have been developed. The HPAM/PEI gel in the presence of dextran sulfate (DS) could reach 120 h in gelation at 100 °C [ 24 ]. It is a promising retarder for PEI crosslinked polymer gel, but it is too expensive.…”

Section: Resultsmentioning

confidence: 99%

“…However, the retarding effect of NaCl was not satisfactory, while the addition of NH 4 Cl reduced the gel strength significantly. Jayakumar et al pretreated PEI with AMPS or dextran sulfate (DS), respectively, and then cross-linked with partly hydrolyzed polyacrylamide (PHPA), which significantly extended the gelation time of PHPA/PEI gel system [ 23 , 24 ]. This approach is not conducive to large-scale application in oilfields due to the inconvenience of preparation and high cost.…”

Section: Introductionmentioning

confidence: 99%

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The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for In-Depth Water Control in Mature Oilfields

et al. 2020

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A delayed crosslinked polymer gel was developed for in-depth water control in mature oilfields. The thermal gelation behavior of nonionic polyacrylamide (NPAM) and PEI was investigated, and sodium citrate (NaCit) was selected as a new retarder to prolong the gelation time. The gelation performance of NPAM/PEI gel system can be adjusted by varying NPAM or PEI concentration, and a quadratic model is developed by statistical analysis, which predicts the gelation time of NPAM/PEI gel system. The obtained model shows high significance and good reliability, as suggested by the F-ratio of 175.16 and high adjusted R-square value (0.9732). The addition of NaCit exhibits a good delayed gelation effect on the NPAM/PEI gel system, better than that of NaCl. The decrease of the initial pH value of the gelling solution leads to the weaker gel viscosity and longer gelation time due to the protonation of amine groups on the PEI chains. Increasing temperature results in higher gel viscosity but shorter gelation time. The gel system in the presence of NaCit exhibits good compatibility with injection and formation water. A dense three-dimensional structure was observed in matured NPAM/PEI/NaCit gel, and it could keep stable below 160 °C. The gel system could effectively reduce the permeability (>95%) and restricted the flow of water after matured in natural cores.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for In-Depth Water Control in Mature Oilfields

et al. 2020

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“…However, the retarding effect of NaCl was not satisfactory, while the addition of NH4Cl reduced the gel strength significantly. Jayakumar et al pretreated PEI with AMPS or dextran sulfate (DS), respectively, and then cross-linked with partly hydrolyzed polyacrylamide (PHPA), which significantly extended the gelation time of PHPA/PEI gel system [23,24]. This approach is not conductive to large-scale application in oilfields due to the inconvenience of preparation and high cost.…”

Section: Introductionmentioning

confidence: 99%

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for Indepth Water Control in Mature Oilfields

Qin¹,

Liao²,

Luo³

et al. 2020

Preprint

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A delayed crosslinked polymer gel was developed for indepth water control in mature oilfields. The thermal gelation behavior of nonionic polyacrylamide (NPAM) and PEI was investigated, and sodium citrate (NaCit) was selected as a new retarder to prolong the gelation time. The gelation performance of NPAM/PEI gel system can be adjusted by the variation of NPAM or PEI concentration, and a quadratic model was developed by statistical analysis, which predict the gelation time of NPAM/PEI gel system. The obtained model showed high significance and good reliability as suggested by the F-ratio of 175.16 and high adjusted R-square value (0.9732). The decrease of the initial pH value of gelling solution leads to the weaker gel viscosity and longer gelation time due to the protonation of amine groups on the PEI chains. Increasing temperature resulted in higher gel viscosity but shorter gelation time. The addition of NaCit showed a good delayed gelation effect on the NPAM/PEI gel system, and the gel system in the presence of NaCit exhibited a good compatibility with injected and formation water. A dense three-dimensional structure was observed in matured NPAM/PEI/NaCit gel, and it could keep stable below 150℃. The gel system could effectively reduce the permeability (>95%) and restricted the flow of water after matured in natural cores.

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“…Polyethyleneimine (PEI) can be used as a crosslinking agent which can react with amide groups to form covalent bonds at high temperature to form network structures. It has been widely used in chemical flooding and water shutoff operations in oilfields [27,28,29,30,31]. In our previous studies, the gel system of PEI cross-linked partially hydrolyzed polyacrylamide was successfully applied to water shutoff treatments [32,33].…”

Section: Introductionmentioning

confidence: 99%

“…In our previous studies, the gel system of PEI cross-linked partially hydrolyzed polyacrylamide was successfully applied to water shutoff treatments [32,33]. The crosslinking reaction rate between PEI and amide groups is mainly dependent on temperature, which could take several days in low or moderate temperature reservoirs [27,28,29,30,31,32], this timeframe cannot meet the requirements of fracturing operations in terms of rapid crosslinking. PEI has been employed to crosslink acrylamide-based polymer fracturing fluids in high temperature situations as high temperature can drastically accelerate the reaction [34,35].…”

Section: Introductionmentioning

confidence: 99%

Improving the Thermal Stability of Hydrophobic Associative Polymer Aqueous Solution Using a “Triple-Protection” Strategy

et al. 2019

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Because of their high viscoelasticity, Hydrophobic Associative Water-Soluble Polymers (HAWSPs) have been widely used in many industrial fields, especially in oilfield flooding and fracturing. However, one major problem which limits the wide applications of HAWSPs is their weak resistance to high temperatures. Once the temperature increases over 100 °C, the viscosity of the fracturing fluid decreases rapidly, because high temperatures reduce fluid viscosity by oxidizing the polyacrylamide chains and weakening the association of hydrophobic groups. To improve the high temperature resistance of one HAWSP, a triple-protection strategy was developed. First, rigid N-vinyl-2-pyrrolidone moiety was introduced into the polymer chains. Second, an environmentally-friendly deoxidizer, carbohydrazide, was selected to prevent polymer oxidization by scavenging dissolved oxygen. Results showed that both the rigid groups and the deoxidizer improved the temperature resistance of the polymer and helped it maintain high viscosity under high temperature and shear rate. Using these two protection strategies, the resistant temperature of the polymer could reach 160 °C. However, the polymer network still got severely damaged at further elevated temperatures. Therefore, as the third protection strategy, the pre-added high temperature responsive crosslinking agent was applied to form new networks at elevated temperatures. The results have shown that the optimized polymer solution as a kind of fracturing fluid showed good temperature resistance up to 200 °C.

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Delayed Crosslink Polymer Gel System for Water Shutoff in Conventional and Unconventional Oil and Gas Reservoirs

Cited by 24 publications

References 0 publications

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for In-Depth Water Control in Mature Oilfields

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for In-Depth Water Control in Mature Oilfields

The Thermal Gelation Behavior and Performance Evaluation of High Molecular Weight Nonionic Polyacrylamide and Polyethyleneimine Mixtures for Indepth Water Control in Mature Oilfields

Improving the Thermal Stability of Hydrophobic Associative Polymer Aqueous Solution Using a “Triple-Protection” Strategy

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