Reduced Rod-tubing Wear And Run Time Increment With Modified Completions In Progressive Cavity Pumped CBM Wells

In conventional rod-driven progressing cavity pumped wells, the issue of rod/tubing wear has always been a concern; especially in CBM wells where the fluid is 100% water which lacks the usual lubricity of oil, combined with the production of coal fines. Adding to the complexity of the problem is the eccentricity of the progressing cavity pump rotor, the rod string completion used, and the production tubing ran. Also in deviated wells due to having high contact loading creates problem. Although all of these together can provide the "perfect storm" for ongoing rod and tubing problems, a proper evaluation of the complete system whereby both the pump, completion and operating parameters are optimized can drastically reduce the occurrence of rod/tubing wear and extend overall run times. This paper will share case studies whereby completions both prior to and after which the pump model, operating parameters and completion practices are evaluated, run times documented and failure mechanisms evaluated to compare and contrast the before and after results of optimizing the total progressing cavity pumping system and the effectivity of the changes made. In order to support the data shared within this work, industry accepted software results will be shared the results of which will provide clear evidence that the modified completions proposed here can and will result in reduced wear, increased run times, and holistically a greater reduction in NPT (Non-Production Time). Although this work is in CBM applications, it will be applicable all rod-driven PC pumped wells.