Investigating the Dominant Factors Influencing Well Screenouts for Crosslinked Fracturing Fluids in Shale Plays

Abstract

One of the properties of guar borate complexed gel systems is the ability to recover dynamic viscosity after being subjected to high shear. This phenomenon is typically referred to as shear rehealing; and the ease of use of guar borate fluids during hydraulic fracturing operations can be partly attributed to this property. While many metal crosslinked fracturing fluid systems exist, and many provide higher proppant pack permeability after well cleanup, their overall use is lower because of higher cost, operational complexity, and perceived higher screenout rates. This paper examines laboratory and operational data to help parse the primary influences of screenouts for different fracturing fluid systems.Extensive laboratory experiments investigating low to moderate shear viscosity tendencies of fluids as well as the low shear proppant transport properties of various fracturing fluid systems were performed to determine if there is a strong correlation between fluid flow properties and proppant transport under shear. The operational data reviewed includes wells with similar completion methods, such as completion tools and well construction methods, and the performance of the tested fluids in the field. Experimental data shows proppant transport under low to moderate shear is possible with all of the fluids investigated, and screenout rates did not show significant correlation to the type of fluid used. The decreased ability for shear rehealing is typically associated with higher bottom hole treating pressure and screenout rates of metal crosslinked fluid systems.In many cases, operators are choosing simplicity of operations over the benefits of using higher quality fracturing fluids. This paper also discusses some of the factors that can help promote surface efficiency, while using the optimal fracturing fluids for the specific well.