Improvement of Impact Strength of Polyglycolic Acid for Self-Degradable Tools for Low-Temperature Wells

Abstract

Abstract Recent increases in the stage count of hydraulic fracturing has increased the time and cost for well completion. Simplifying time-consuming processes is crucial for economic success. The use of degradable materials for components of downhole tools has several advantages, such as eliminating or simplifying the recovery process of the tools. Polyglycolic acid (PGA), a hydrolyzable polymer, is a suitable material for these components. PGA has already been used in frac balls because of its high mechanical strength and appropriate degradation characteristics. However, in low-temperature wells close to the glass transition temperature of PGA, there are problems with tool breakage during installation or stimulation because of the changes in the mechanical properties of PGA at low temperatures. This paper focuses on the improvement of the impact strength of PGA. A study of modifiers identified the additives that are highly compatible with PGA. Morphological studies of mixtures showed finely dispersed additive domains within a PGA matrix. The impact strength of the mixture was twice as high as that of neat PGA. A formulation was identified that optimized the impact strength while retaining degradability, processability, and machinability similar to that of neat PGA. The improvement of the impact strength broadens the range of applications that PGA tooling is suitable for and helps to reduce the cost and time of the well completion process.