β-cyclodextrin polymer microsphere as a potential filtration reducer in water-based drilling fluids for high temperature application

As the search for energy increases, the drilling depth has increased dramatically due to the progress of drilling technologies over the past years. Therefore, elevated temperature gradients and hostile environments are increasingly encountered than before. As the temperature increasing with the well depth, thermal stability has become an important requirement for drilling fluids. To ensure safe, successful, and economical drilling in such harsh environments, maintaining the drilling fluids’rheological and filtration properties stable when exposed to high temperatures is essential. Generally, oil-based drillingfluids are the first choice because they offer stable rheological and filtration properties in a wide range of temperatures, and result in consistent and predictable fluid properties with minimum treatment and operation costs, however, the high cost and increasingly stringent environmental regulations restrict their wide use. Therefore, hunting for a water-based drilling fluid with high temperature stability is preferred and desired.

As one of the key properties,filtration control in high temperatureenvironments for water-based drilling fluids has been paid much attention. For most water-based drilling fluids, they can only withstand the bottom hole temperature lower than 300 °F due to the dependence of biopolymers. These biopolymers, primarily polysaccharides, are frequently used in water-based drilling fluids to impart desired rheological properties and filtration control.

In this work, the feasibility of using the β-CD polymer microspheres (β-CDPMs) as a potential candidate for improving drilling fluid filtration properties is investigated. The preparation routes of β-CDPMs by inverse emulsion synthesis method is described first, followed by characterization of the structure, morphology, and thermal stability using Fourier transform infrared (FTIR) spectra, scanning electron microscope (SEM), and thermogravimetric analysis (TGA) respectively. Subsequently the filtration control capacity of β-CDPMs on the bentonite-based drilling fluid before and after thermal aging at various aging temperatures is studied. Finally the underlying mechanism of the microspheres to control the filtration is elucidated in details.

Zhong et al. (2020) Insight into β-cyclodextrin polymer microsphere as a potential filtration reducer in water-based drilling fluids for high temperature application. Carbohydrate Polymers 249, 116833. https://doi.org/10.1016/j.carbpol.2020.116833