Case Study: Advancing Fracture-Stimulation Design in Tight and Unconventional High-Temperature Reservoirs to Maximize Gas Recovery

The attainment of commercial gas rates in reservoirs exhibiting permeability below 5 mD presents a daunting task. Since 2011, X has undertaken a strategic approach to confront this challenge by implementing fracture-stimulation in seven gas wells. The primary goal has been to elevate gas rates and recoveries beyond the achievements of previous non-fracture-stimulated completions within the same field, compounded by formidable obstacles such as high temperature (reaching 325°F) and the robust strength of reservoir rock. The initial fracture-stimulation campaigns spanning from 2011 to 2013 yielded less-than-ideal outcomes. Inadequate material selection and frac design resulted in initial gas rates averaging 10-20 MMcf/d, with alarming decline rates of 80% per year. The root causes were traced back to crushed proppant and proppant flowback to the wellbore after several months of production. In 2015, the second fracture-stimulation campaign marked a pivotal turning point. Leveraging insights from the 2011 campaign, the approach was revamped. The frac carrier fluid transitioned to Hi-Temp Frac Fluid, offering enhanced load capacity and temperature tolerance. Proppant composition shifted from a combination of sizes 12/18 & 20/40 to High Strength Proppant (HSP) 16/30, strategically preventing proppant crushing. Perforation density was increased from 5 SPF to 6 SPF, aiming to reduce tortuosity. Simultaneously, adjustments were made to proppant flowback material, guided by promising laboratory testing outcomes. The implementation of these changes culminated in the successful fracture-stimulation of Q-12 and Q-14. Fracture Conductivity witnessed a remarkable 221% increase, propelling initial gas rates for Q-12 and Q-14 to 60 MMcf/d and 50 MMcf/d, respectively. This paper intricately explores the transformative enhancements in design and materials that defined the 2015 fracture-stimulation campaign. With a focus on transitioning from dealing with oil wells to confronting the distinctive challenges of gas wells, this narrative serves as a manual of success—an illuminating guide for extracting more gas from the intricacies of challenging reservoirs.