Optimizing Hydraulic Fracturing Performance in Depleted Sandstone Reservoirs: The Role of Pre-Pad Solution in Fluid Recovery and Productivity Improvement

Abstract In the BED16C6 field, located in the Western desert, Egypt, the Abu Roash (G) sandstone reservoir has been one of the most developed reservoirs that mainly produce via hydraulic fracturing. A significant challenge associated with hydraulic fracturing in conventional depleted reservoirs is the potential formation damage induced by frac-fluid, which can impair a well's post-fracturing performance. This paper examines the impact of injecting a pre-pad solution comprising a high concentration of oxidizing breaker, a microemulsion surfactant, and acetic acid prior to pumping the crosslinked fluid into the formation. This approach is particularly relevant when higher-than-standard gel loadings are used. The use of highly concentrated crosslinked gel fluids often results in increased gel residue, leading to greater formation damage and reduced regained permeability. Frac-fluid formulations typically incorporate surfactants and breakers with the desired concentrations to facilitate the post frac clean-up process, reduce surface and interfacial tension, promote fluid recovery, and prevent emulsion formation. Although the concentrations of surfactants and breakers are carefully designed to effectively break the frac-fluid and help prevent emulsion formation, they may be insufficient to completely break the fracturing fluid in depleted sandstone formations, particularly under high gel loading conditions. With the concept of a pre-pad solution, high breaker concentration, high acetic acid concentration, and high surfactant concentration aims to break any remaining gel residues, therefore enhancing frac-fluid recovery and ensuring no generated emulsions, thus, leading to higher post frac productivity. Post-frac well testing demonstrated enhanced fluid recovery and productivity in wells treated with the pre-pad technique, compared to offset wells with similar reservoir and formation characteristics. The pre-pad approach has been successfully implemented in multiple wells in the Western Desert of Egypt. This paper focuses on a specific case study in the Abu Roash (G) formation, comparing post-frac well performance with offset wells to assess the impact of the pre-pad solution. This study highlights the significant potential of pre-pad solution for optimizing hydraulic fracturing operations in challenging, depleted sandstone reservoirs.