Remotely Activated Microcapsules for Oil Recovery Treatments

Malgorzata Natalia Mazurek

Research output: Book/ReportPh.D. thesisResearch

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Abstract

Water-flooding is a commonly used oil recovery method in mature reservoirs, because injected water enhances oil sweep efficiency and leads to increased oil production. Due to the occurrence of fractures in water-flooded reservoirs, excessive water production is observed. Hence, water shut-off treatments are extensively investigated, though currently applied materials still suffer from some disadvantages. The main drawback is lack of control over the setting of plugs in the fracture, and this may cause blocking of the injection well and the formation of the plug before placing the material in the fracture. Secondly, only a few developed materials prevent from blocking oil-rich pores, and yet they are not able to create a permanent plug, as they do not form a covalently bonded structure.
The aim of the project is to design a novel plugging material which can block fractures without affecting the pores and ensure permanent water shut-off treatment. To eliminate the danger of premature plug formation, stimulus-responsive materials were investigated. Considering that fractures are extremely hard-to-access places, the designed material should respond to a remotely applied stimulus, in order to achieve better control over plug formation.
The developed material consists of vinyl-functional polydimethylsiloxane (PDMS) microparticles and microcapsules with an encapsulated PDMS cross-linker. Due to reactions between the released cross-linker and vinyl groups on the PDMS microparticles’ surface, a covalently bonded elastomer plug is formed. The size of both components is adjusted to allow for creating the plug without affecting the pores. Control over cross-linking is achieved through an encapsulation process. Microcapsules prepared via a phase separation method are impermeable at 50°C, thereby eliminating premature plug formation. It is shown that after heating microcapsules to 120°C, the cross-linker is released from a poly(methyl methacrylate) (PMMA) shell. Moreover, gamma irradiation of the microcapsules decreases the Tg of the polymeric shell, changing the permeability of the microcapsules. Due to the irradiation process, microcapsules become permeable at lower temperatures, and a remotely applied activation has been achieved. Applying the alternating magnetic field (AMF) was another activation method investigated as part of this research. Magnetic nanoparticles, which generate heat on exposure to the AMF, were encapsulated successfully within the polymeric shell, and as a result, heating microcapsules when they are subjected to the AMF is possible. As an alternative to remote activation methods, solvent-flushing was examined, allowing for an investigation into the plug being cross-linked under high-pressure. Compressed material created a uniform, void-less structure capable of withstanding harsh conditions in reservoirs.
Original languageEnglish
Place of PublicationKgs. Lyngby
PublisherTechnical University of Denmark
Number of pages124
Publication statusPublished - 2016

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