Performance of PHPA Polymer Slurries for Applications in Missouri Shale

A laboratory experimental program was conducted to evaluate the performance of partially hydrolyzed polyacrylamide (PHPA) polymer drilling slurries for applications in Missouri shale. The series includes drum slake, jar slake, linear swell, and hardness testing for representative Missouri shale specimens allowed to interact with a variety of commercially available PHPA slurries. Slurries were prepared at concentrations ranging from 25% to 150% of manufacturer-recommended mixing ratios (by mass for solid polymers, by volume for liquid polymers) to examine the associated effects on performance. Indices used to quantify performance in terms of slaking, swelling, and softening inhibition are shown to be relatively insensitive to polymer manufacturer and form (granular or emulsified) but significantly sensitive to concentration. The performance indices improve with increasing slurry concentration and appear to reach optimum values at the recommended mixing ratios. Over-concentration does not enhance, and may diminish, slurry performance.