Experimental study of small-sized polymeric microgel (SPM) in low- or median-permeability reservoirs

Zhang, Jihong; Tan, Xinjian; Zhao, Xinrui; He, Qingbin; Wang, Yanan

doi:10.1016/j.petrol.2019.106829

Cited by 5 publications

(4 citation statements)

References 20 publications

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“…It is also expected that treating the negatively charged sandstone rocks with the positively charged CPAM and reducing the salinity would induce electrochemical alteration to rock pore surfaces. , Such a change may render the pore surface less water wet, to some extent, thus decreasing water layer thickness at the rock surface. ,,,,− To test the hypothesis, we performed core flooding experiments using three type of sandstone rocks (e.g., Socito, Gray Bandera, and San Saba) with permeabilities ranging from 2.7 mD to 80 mD, using KCl aqueous ionic solutions with two different salinities (e.g., 0.2 and 2 wt %). The rock permeability range selected in this work (i.e., 2 mD to 80 mD) has been categorized as “low”, in accordance with the recent investigations on this subject (e.g., ,− ). Note that a “low-permeability” rock does not mean “tight or unconventional” as the latter is more rigorously defined by a rock having a permeability of <0.1 mD. , …”

Section: Introductionmentioning

confidence: 99%

Low-Salinity-Assisted Cationic Polyacrylamide Water Shutoff in Low-Permeability Sandstone Gas Reservoirs

et al. 2020

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The application of polymer-based relative permeability modifiers (RPM) in low-permeability sandstone reservoirs has long intrigued production engineers. We hypothesize that lowering salinity may expand the application of the cationic polyacrylamide (CPAM) in low-permeability sandstone gas reservoirs, because of the favorable polymer–polymer physiochemical interaction at pore surfaces. To test this hypothesis, we conducted six core-flooding experiments to examine the relative permeabilities of water/gas before and after CPAM treatment, as a function of salinity using sandstone core plugs. Moreover, we measured zeta potentials of polymer–polymer, rock–polymer, and rock–brine interfaces before and after the RPM treatment, as a function of salinity. We also measured the contact angles for silicate/brine systems before and after the treatment as a function of salinity. Core-flooding results show that reducing the salinity decreases the water relative permeability but with marginal effect on the gas relative permeability. Lowering salinity also decreases the effective polymer layer thickness at pore surfaces. Moreover, the adsorption of the CPAM onto the negatively charged sandstone rock, together with lowering brine salinity, increases hydrophobicity of the rock. Thus, our results suggest that polymer–polymer interactions at pore surfaces govern the performance of CPAM in low-permeability sandstone rocks.

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Section: Introductionmentioning

confidence: 99%

Low-Salinity-Assisted Cationic Polyacrylamide Water Shutoff in Low-Permeability Sandstone Gas Reservoirs

et al. 2020

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“…The in situ gel can transport deep into the reservoir and thus perform indepth treatments. However, preformed gel, considering the gel particle size and injectivity, usually aims at plugging extra-large permeability channels such as fractures . It tends to be more stable compared to the in situ gel since its performance is independent of the gelation time and the composition of the gelant, which may vary during transport .…”

Section: Introductionmentioning

confidence: 99%

“…However, preformed gel, considering the gel particle size and injectivity, usually aims at plugging extra-large permeability channels such as fractures. 4 It tends to be more stable compared to the in situ gel since its performance is independent of the gelation time and the composition of the gelant, which may vary during transport. 5 Even though the development of microgels and nanogels broke the boundary a little, in situ gel is still very commonly used now.…”

Section: Introductionmentioning

confidence: 99%

Application of a Salt-Resistant In Situ Cross-Linked Terpolymer Gel for the Daqing Oilfield

et al. 2023

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Pubei Block, which is a subdivision of Daqing Oilfield, presents a challenging environment for conformance control due to its high temperature (average 80 °C) and salinity (13,451 mg/L), making it difficult for the polyacrylamide-based gel to maintain the necessary gel strength. To address this issue, this study aims to evaluate the feasibility of using a terpolymer in situ gel system that provides greater temperature and salinity resistance and pore adaptation. The terpolymer used here consists of acrylamide, acrylamido-2-methylpropane sulfonic acid, and N,N'dimethylacrylamide. We determined that a formula with a hydrolysis degree of 15.15%, a polymer concentration of 600 mg/L, and a polymer−cross-linker ratio of 2.8 yields the greatest gel strength. The hydrodynamic radius of the gel was found to be 0.39 μm, indicating no conflict with the pore and pore-throat sizes determined by the CT scan. In the core-scale evaluation, the gel treatment improved oil recovery by 19.88%, of which 9.23% was through gelant injection and 10.65% through post water injection. A pilot test began in 2019 and has continued for 36 months until now. Within this period, the oil recovery factor increased by 9.82%. The number is likely to keep going up until the water cut (so far 87.4%) reaches the economic limit.

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“…Features like small size, elasticity, and better deformability allow the migration of microspheres towards smaller pores and deeper formation with lower permeability. Different types of polymer microspheres with unique characteristics have been proposed in the literature and widely applied in the oil field [29][30][31][32][33]. The plugging performance of polymer microspheres and the aspects impacting its plugging and migration have been previously investigated [22,23,34,35].…”

Section: Introductionmentioning

confidence: 99%

Pore-Scale Investigation on the Plugging Behavior of Submicron-Sized Microspheres for Heterogeneous Porous Media with Higher Permeability

Liu

Yang

Wu³

et al. 2020

Geofluids

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Reservoir heterogeneity is regarded as one of the main reasons leading to low oil recovery for both conventional and unconventional reservoirs. High-permeability layers or fractures could result in ineffective water or gas injection and generate nonuniform profile. Polymer microspheres have been widely applied for the conformance control to overcome the bypass of injected fluids and improve the sweep efficiency. For the purpose of examining the plugging performance of submicron-sized microspheres in high-permeability porous media, systematic investigations were implemented incorporating macroscale blocking rate tests using core samples and pore-scale water migration analysis via nuclear magnetic resonance (NMR). Experimental results indicate that microsphere particle size dominates the plugging performance among three studied factors and core permeability has the least influence on the plugging performance. Subsequently, microsphere flooding was conducted to investigate its oil recovery capability. Different oil recovery behaviors were observed for cores with different permeability. For cores with lower permeability, oil recovery increased stepwise with microsphere injection whereas for higher permeability cores oil recovery rapidly increased and reached a plateau. This experimental work provides a better understanding on the plugging behavior of microspheres and could be employed as a reference for screening and optimizing the microsphere flooding process for profile control in heterogeneous reservoirs.

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Experimental study of small-sized polymeric microgel (SPM) in low- or median-permeability reservoirs

Cited by 5 publications

References 20 publications

Low-Salinity-Assisted Cationic Polyacrylamide Water Shutoff in Low-Permeability Sandstone Gas Reservoirs

Low-Salinity-Assisted Cationic Polyacrylamide Water Shutoff in Low-Permeability Sandstone Gas Reservoirs

Application of a Salt-Resistant In Situ Cross-Linked Terpolymer Gel for the Daqing Oilfield

Pore-Scale Investigation on the Plugging Behavior of Submicron-Sized Microspheres for Heterogeneous Porous Media with Higher Permeability

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