Nanofluidos contendo nanomateriais de carbono aminados : preparo e propriedades

Abstract

In order to ensure a high degree of dispersion and transfer their outstanding mechanic, rheological, and thermal properties to other matrices and solvents, carbon nanotubes (CNT) and graphene can be chemically modified by inserting oxygenated and amino groups into their structure. Partially hydrolyzed polyacrylamide (HPAM) is a water-soluble polyelectrolyte of high viscosifying character, which is commonly used in improved oil recovery (IOR) processes. However, at high temperatures and high salt concentration, HPAM undergo hydrolysis of the acrylamide groups, resulting into a viscosity decrease. This will negatively affect the IOR sweeping performance, and thus, an outcome of economical and energetic undesired consequences. This Ph.D. research was divided into three series. In the first series, the objective was to study the system composed by previously oxidized amino-CNT, treated with triethylenetetramine (TETA). For this, a synthesis methodology was carried on, so TETA-CNT were obtained. Then, the colloidal properties of TETA-CNT nanofluids (NF) were studied when dispersed in both water and HPAM solutions. At last, a rheological study was performed on both aqueous TETA-CNT NF and HPAM + TETA-CNT NF, in order to evaluate their chemical decomposition under oil and gas reservoir conditions. In the second series, the whole process of series 1 was repeated, yet, using graphene oxide (GO) aminated with TETA. The third series was proposed as an exploring scope and its goal was to study both colloidal and rheological properties TETA-GO:TETA-CNT hybrids NF. The synthesis methodologies carried on showed to be energetically viable and had a low environmental impact, allowing to obtain carbon nanomaterials with high structural and morphological quality. In addition, the presence of amine groups into the carbon nanomaterials (CNM) structure was confirmed by CHN, TG/DTG and FTIR techniques. The colloidal study showed that all carbon NF display high surface charge and apparent particle sizes in the nanometer range. Finally, the rheological study showed the great influence of the morphology of the nanoparticles on their spatial organization. Besides, a viscosity gain was observed in TETA-CNT NF and TETA-GO:TETA-CNT hybrids NF, confirming the applicability of these CNM in IOR processes.