This work aims to evaluate the thermal degradation of carboxymethyl cellulose (CMC) in solution in the presence of salt, as well as to study the correlation of the rheological behavior of these solutions with exposure to temperature. Step 1 involved characterizing powdered low- and high-viscosity CMC using SEM, FTIR, TGA/DrTGA, and DSC. In step 2, CMC solutions in fresh and saline water were characterized by TGA/DrTGA and viscosity tests. Step 3 exposed saline solutions to 70–150 °C for varying times, followed by TGA/DrTGA and viscosity analyses. There were no significant differences in the thermal degradation of LV and HV CMC, nor in terms of the physical state of the polymer. The results demonstrate that the use of CMC necessitates a combined analysis of thermal degradation and rheological behavior.

Formation damage caused by wellbore fluids remains a key concern in carbonate reservoirs, where pore plugging and filtrate invasion can severely reduce permeability. This study investigates the influence of filtrate-control components in cellulose-based polymeric fluids on the potential for formation damage in carbonate rocks and evaluates the performance of HPA starch as an alternative to cellulose, focusing on its comparative effects on formation permeability. Experimental tests were performed using Indiana Limestone cores to measure filtration behavior and permeability recovery after exposure to different polymeric solutions. The results revealed distinct mechanisms associated with each additive: PAC LV controlled fluid loss mainly by adsorption and pore plugging, while HPA starch formed more deformable and permeable structures. Glycerin, when used alone, did not induce formation damage but increased fluid viscosity, favoring more stable dispersion of the polymeric phase. Micronized calcite enhanced external cake consolidation through particle bridging. The combined use of PAC LV, glycerin, and calcite provided the most efficient filtration control and minimized formation damage. These findings contribute to understanding the isolated and synergistic roles of filtrate-control agents and support the design of optimized polymer-based fluids for well intervention and abandonment operations.

Polymeric fluids are widely applied in workover operations because of their ability to control well pressure, regulate filtrate loss, and preserve reservoir productivity. However, their performance is highly dependent on polymer stability, since degradation under thermal, mechanical, or chemical stresses can compromise rheology, weaken filtration control, and increase the risk of formation damage. Research since the 1970s has advanced toward developing improved formulations, aiming to enhance efficiency while reducing reservoir impairment. Laboratory characterization techniques have been essential in evaluating polymer degradation and fluid–rock interactions, generating insights for polymer selection and fluid design. Within this context, this study proposes a literature review on polymeric fluids in workover operations, with emphasis on the role of polymers in fluid formulation and performance. The review also addresses operational fundamentals and technical challenges, focusing on thermal stability, degradation mechanisms, and strategies to minimize formation damage through adequate formulation and characterization approaches.