Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Encapsulation and controlled release of HCl in PDMS capsules
Submission Author:
Ademir Medeiros , RJ
Co-Authors:
Ademir Medeiros, Mateus de Lima, Amanda C. S. N. Pessoa, Bruna Leopercio, Marcio CARVALHO
Presenter: Ademir Medeiros
doi://10.26678/ABCM.COBEM2023.COB2023-1591
Abstract
Water injection is one of the most studied and used methods in oil recovery. However, long-term water injection in naturally fractured reservoirs (NFR), which are common in carbonate rocks and represent significant amounts of oil and gas reserves, leads to reduced formation sweep since the injected water flows primarily through fractures. There has been an increasing interest in fracture flow in recent years. In fractured reservoirs with high porous heterogeneity, the formation of highly permeable preferential paths yields early water breakthrough, excess of water production and, as a result, a low oil recovery efficiency. Thus, enhanced oil recovery methods (EOR) are applied to mitigate this non-uniform oil sweep. Gel treatment in the injection wells is one of these methods. It consists in blocking off the high permeability path with a polymeric gel to divert subsequently injected water into less-permeable, oil-bearing pores. However, in this case, because the polymer is injected with its cross-linker the gelation time is not predictable. Therefore, it is not possible to control the depth that the chemicals will reach in the fracture before solidifying. Alternatively, microcapsules can be used to encapsulate the cross-linker or the polymer making it possible to completely fill the fracture before activating the gelation. It allows controlling the timing and location of the content release. The capsules features must make them mechanically stable and impermeable to the encapsulated material during storage. In this work, we propose the encapsulation of sodium silicate (Na-Si) gel activator, hydrochloric acid (HCl), making it possible to better control the gelation system to reach deeper locations of the fractured reservoir and, thus, improve oil recovery. Microcapsules with a poly(dimethyl siloxane) PDMS shell are produced using a microfluidic device which combines co-flow and flow-focusing in coaxial glass-capillaries. HCl release in hypotonic media (water) evaluation was made through pH measurement. Due to the osmotic difference, capsules swell until burst. Results show that the release time can be controlled by changing the eccentricity and rigidity of the capsules.
Keywords
microcapsules, PDMS, gelation
