Abstract
With the increase in gas demand and the need to supply additional energy, the focus is now shifted to drilling and production activities exploiting high-pressure/high-temperature (HPHT) tight sandstone gas formations. The design optimization and selection of proper hydraulic fracturing technology is a key to succeeding in getting an economic gas production rate. Using well performance as the primary determining factor, a systematic study and evaluation was conducted on 20 vertical and horizontal wells drilled in HPHT heterogeneous sandstone reservoirs to assess effectiveness of stimulation treatments and benefits of using novel technologies. The numerous variables analyzed to determine the impact on production include different completion options, type of fracturing technology used, various proppant and fluids, fracturing method, production rate, and flowback parameters. A comprehensive database for stimulated wells was created that included reservoir parameters, completion data, minifrac and main stimulation treatment parameters (additives, fluid and proppant types, volumes, rates, and pressures), post-fracturing flowback results, and monthly production data. The production data were normalized on reservoir quality to strengthen the effect of fracturing parameters on well productivity independent of reservoir quality. Correlations were drawn using the Pearson correlation coefficient to compute the upward and downward data trends, ensure use of good quality data, and discard the few nonaligned data. Numerous very useful plots were constructed that show the different trends of the variables evaluated and how they affect production rate.
The results demonstrate the importance of proper well landing with strong influence of reservoir quality on postfracturing production results. The channel fracturing technique offers near-infinite fracture conductivity and shows very promising results compared with conventional treatments. Pumping the bigger fracturing jobs typically yields better production results, but proppant type and schedule should be designed accounting for reservoir quality. Pad volume should be designed to achieve optimum pressure at the end of the treatment, not too high but not too low. Post-fracturing production parameters are as important for the well performance as the stimulation treatment itself. The analyses identified the key post-fracturing production drivers in the gas reservoirs and ways to improve production of future wells drilled in various formations under similar conditions.
