During fracturing operations, large amounts of proppant are injected with hydraulic fracturing fluid. Usually, various sizes of proppant are selected based on the desired fracture parameters. Smaller mesh size sands, 40/70 mesh or smaller, were traditionally pumped as a means of leakoff control agent. In unconventional ultra-low permeability reservoirs, however, their application has expanded to be a conductive propping agent. In many cases, these sands represent up to 100% of all proppant injected. A good understanding of the production performance of those wells is necessary for the further application of small mesh sands as proppant.
This study investigated the performance of small sized proppant in terms of post-fracturing production. Completion, stimulation, and production data from multiple databases, both external and in house, was collected, cleansed, and consolidated to conduct analyses. The final data set contains those wells that used at least 90% of the total proppant in the 40/70 mesh or smaller, and offset wells that were located within certain distance to those target wells. Production metrics such as 12-months cumulative production and decline behavior were compared between the target wells and their offsets to evaluate the performance of the small mesh sands as proppant.
At the same specific gravity, smaller proppants transport further and have higher stress resiliencies compared to larger size proppants. However, their conductivity is lower. The post-fracturing production performance is then highly correlated to the propped hydraulic fracture length, height, and width as well as the permeability of the proppant pack. Data from several major unconventional plays in the United States, Eagle Ford, Wolfcamp, and Haynesville, were studied. The results were mixed. Wells using smaller proppant as the majority proppant demonstrated different production performance compared to their offsets in different unconventional plays. Small mesh sands showed better production results than their offsets in some cases but demonstrated no statistical significant difference in others. Since many parameters can affect hydrocarbon production performance of a well and proppant size is only one of them, physics-based analysis is referred to help interpret the results.
Insights derived from this study help justify if a particular formation a good candidate for using smaller proppant as the major conductive agent and what other treatment design parameters should be considered to achieve the best performance.