Polymer flooding represents the most common chemical enhanced oil recovery (CEOR) method used at commercial scale. In this process, the polymeric solutions (generally hydrolyzed polyacrylamide - HPAM) are injected to improve the oil/water mobility ratio (M). However, due to mechanical, chemical, bio, and thermal degradation, polymer viscosity losses can occur, causing a negative impact on oil sweep efficiency. In this case, biopolymers seem to be promising candidates in EOR applications with special structural characteristics, which result in excellent stability in harsh environments with high temperatures, ionic forces, and shear stresses. This paper presents the laboratory evaluation of Scleroglucan (SG) and a commercial sulfonated polyacrylamide (ATBS) in synthetic brine, representative of a Colombian heavy-oil field. The effects of ionic strength, pH, temperature, and shear degradation effects on polymer viscosity were also evaluated. For SG, the results reflect its tolerance to high salinities (0-5%wt), ionic strengths (Na+, K+, Ca2+, and Mg2+), shear rates (0-300,000 s-1), temperatures (30, 50, 80 and 100 °C), and pH variations (3-10). The biopolymer was capable of preserving its viscous properties and stability after of the effect of these variables. Finally, the target viscosity (set as 17 cp) was achieved with a lower concentration (2.7 times) than the ATBS polymer tested.

Polymer flooding consists of injecting polymer-augmented water into the reservoir to control the water-oil mobility ratio, resulting in an increase in the volumetric sweep efficiency compared to water flooding. Synthetic polymers (polyacrylamides) and biopolymers (scleroglucan, xanthan gum, schizophyllan) are the two families of polymers usually evaluated for enhanced oil recovery (EOR). Scleroglucan (SCG) is resistant to electrolytes, hydrolysis, pH (3-10) and temperature (30-100°C) and has remarkable rheological properties, but it is quite susceptible to microbiological degradation. The primary objective of this study was to evaluate the biodegradation of SCG in the injection and production processes and its aquatic toxicity. The anaerobic biodegradation of the SCG solutions was determined through the viscosity changes of the solutions, while the aerobic biodegradation was calculated with the changes in the SCG concentration.  It was observed that the viscosity reduction of the SCG solution was 30% and the SCG concentration decreased from 100 ppm to 52 ppm because bacteria can metabolize the biopolymer. Daphnia Pulex, Scenedesmus Acutus and Oreochromis sp. were the organisms used in the ecotoxicological assays of the SCG solutions. The acute ecotoxicological bioassays showed that there was no evidence of acute deleterious effects of SCG on any of the three organisms. From the chronic ecotoxicological bioassays, it was concluded that there was no effect of SCG on the mortality of Daphnia Pulex, regardless of the tested SCG concentration.

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Aviable option for the sustainability of hydrocarbon supply in the short and medium term is increasing the expected ultimate oil recovery factor through Enhanced Oil Recovery processes (EOR). f .The purpose of this paper is to describe a methodology to evaluate EOR technologies developed at the Instituto Colombiano del Petróleo (ICP) of ECOPETROL S.A. in 2012. The methodology includes theoretical evaluation, design (geological analysis, engineering analysis, laboratory static and dynamic tests and numerical simulation, among others), field implementation and surveillance of Colloidal Dispersion Gels (CDG) injection. CDG is an EOR method that consists in the co-injection of high molecular weight polymer and a crosslinker, to generate microgels in the reservoir. This technology has become an alternative to polymer flooding.This paper describes a field application in Dina Cretáceos Field (Dina) supported by the proposed methodology, which corresponds to the first chemical enhanced oil recovery pilot implemented in Colombia by ECOPETROL S.A. Results of this study show an increase in volumetric sweep efficiency due the improvement of the mobility ratio, increasing in oil production and decreasing in water production. Based on the results of this pilot, which started in June 2011, the feasibility of expanding the use of CDG technology in Dina and others fields of Colombia is being assessed at present. ABSTRACT 62U ma opção viável para garantir a sustentabilidade do fornecimento de hidrocarbonetos a curto e médio prazo é o aumento do fator de recuperação última das jazidas, mediante a implantação de métodos de recuperação melhorada (EOR, por suas siglas em inglês).Este artigo tem como objetivo descrever uma metodologia para avaliar tecnologias EOR desenvolvida no Instituto Colombiano do Petróleo (ICP) de ECOPETROL S.A., em 2012. A metodologia compreende uma avaliação teórica, desenho (análise geológica, análise de engenharia, provas estáticas e dinâmicas em nível de laboratório e simulação numérica), execução em campo e monitoramento de processos de injeção de géis de dispersão coloidal (CDG, de suas siglas em inglês), CDG é um método EOR que consiste na coinjeção de polímero de alto peso molecular com um agente entrecruzador que permite a geração de micro géis na formação. Esta tecnologia converteu-se em uma alternativa aos processos de injeção de polímero.Neste trabalho inclui-se um caso de aplicação no Campo Dina Cretáceo (Dina) da metodologia proposta, que corresponde ao primeiro piloto de recuperação química na Colômbia realizado por ECOPETROL S.A. Os resultados deste estudo mostram um aumento na eficiência volumétrica de varrido devido à melhoria da relação de mobilidade, dando lugar a um aumento na produção de petróleo e uma diminuição da produção de água. Com base nos resultados deste piloto, que iniciou sua execução em junho de 2011, atualmente avalia-se a factibilidade de expandir o uso da tecnologia CDG em Dina e em outros campos da Colômbia.

Partially Hydrolyzed Polyacrylamide (HPAM) is the polymer most used in chemical enhanced oil recovery (cEOR) processes and it has been implemented in several field projects worldwide. Polymer injection has shown to be an effective EOR process. However, it has not been implemented massively due to HPAM polymer's limitations, mostly related to thermal and chemical degradation caused by exposure at high temperatures and salinities (HTHS). As an alternative, a new generation of chemically stable monomers to improve the properties of HPAM has been assessed at laboratory and field conditions. However, the use of enhanced polymers is limited due to its larger molecular size, large-scale production, and higher costs. One of the alternatives proposed in the last decade to improve polymer properties is the use of nanoparticles, which due to their ultra-small size, large surface area, and highly reactive capacity, can contribute to reduce or avoid the degrading processes of HPAM polymers. Nanoparticles (NPs) can be integrated with the polymer in several ways, it being worth to highlight mixing with the polymer in aqueous solution or inclusion by grafting or chemical functionalization on the nanoparticle surface. This review focuses on hybrid nanomaterials based on SiO2 NPs and synthetic polymers with great EOR potential. The synthesis process, characterization, and the main properties for application in EOR processes, were reviewed and analyzed. Nanohybrids based on polymers and silica nanoparticles show promising results in improving viscosity and thermal stability compared to the HPAM polymer precursor. Furthermore, based on recent findings, there are great opportunities to implement polymer nanofluids in cEOR projects. This approach could be of value to optimize the technical-economic feasibility of projects by reducing the polymer concentration of using reasonable amounts of nanoparticles. However, more significant efforts are required to understand the impact of nanoparticle concentrations and injection rates to support the upscaling of this cEOR technology.