This paper presents post-fracture deliverability results for 56 gas-storage wells over a two- to five-year period. Of the wells studied, 32 had a surface modification agent (SMA) applied to the proppant during the hydraulic fracturing treatment. The other 24 wells included in this study had no additives applied to the proppant for sand flowback control.

The deliverability results from actual flow tests are used to evaluate how absolute open flows (AOF) held up over multiple injection and withdrawal cycles involving significant pressure differentials. The results are compared for the large data sets of wells that did and did not include the SMA in the fracture treatment. In general, the data set for wells that did not include an SMA have been through four or five complete pressure cycles. After some operational problems, the need for proppant flowback control became apparent, and later frac treatments usually included the SMA. The wells that included a SMA have been through two or three complete pressure cycles.

This study was completed to alleviate the operators concern about the long-term impact of the SMA on the well performance. While the SMA effectively achieved the short-term goal of proppant-flowback control, the operator was concerned that the fracture might be more prone to a reduction in conductivity or simple clogging.

Typically, a new product or process gets a lot of attention and study. Many times the well results are tracked only for a year or less and the product or process becomes common or discarded. Longer-term studies on a product or process are less common, perhaps due to time, manpower, cost constraints, personnel changes, and a variety of other reasons. Over time, information can easily get buried in a sea of data. Wells using the once-new product or process are forgotten unless a serious problem occurs. The reason the product or process was first used may even be forgotten if it solved the problem.

While results may vary from formation to formation, this longer-term look at the results of SMA, injected with the proppant, should help fracture treatment designers convince the skeptics that proppant-flowback control can achieve its immediate objective and match or exceed long-term performance expectations.

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