Case Studies: Improved Performance of High Brine Friction Reducers in Fracturing Shale Reserviors

Abstract

The primary purpose of friction reducers (FR's) used in stimulating shale reservoirs is to overcome tubular friction pressure and establish high pumping rates. Slickwater (or water frac treatments where friction reducers are used as main source of reducing tubular pressure) fracturing has increased significantly with the advent of horizontal shale stimulation. Technologies, including multi-stage fracturing of horizontal wells have increased frac volume requirements per well. Recent restrictions limiting fresh water usage and environmental concerns of flowbacks have created challenges for operators to adopt mechanical and chemical water treatment means to remove impurities from flowbacks for reuse in slickwater fracturing. However, most treatments do not remove brines from the water requiring development of high brine tolerant friction reducer to maintain high performance. This study presents experimental and case studies of various cationic and anionic FR's of the similar molecular weight in high brine flowbacks collected from two major shale plays. Finger print water analyses of shale reservoirs were used as brine source for evaluation. Dynamic friction loop flow apparatus was used to evaluate the rheological properties and formation damage of the FR where high brine waters are being used as the main source of slickwater fracs. Field data collected for two case histories document the ability of the high brine tolerant friction reducers to perform at a level consistent with traditional products used in fresh water. This confirms the experimental flow data obtained from dynamic friction loop investigations. Results obtained from this study can be used to optimize slickwater frac treatments where flowbacks are the main source of frac water. Primary objectives include.• Comparison studies of new high brine tolerant friction reducer with conventional FR's used in the oilfield.• Experimental data illustrating the performance of newly developed FR's in high brine shale flowbacks. Cost advantage can be realized by using less polymer, while reducing fresh water and disposal of the flowbacks.(will be addressed at a later publication) • Case studies of wells treated with the new friction reducers show performance in brines similar to these achieved with conventional FR's when used in fresh water.

On the cost of electrodialysis for the desalination of high salinity feeds

“…(13) it is clear that the energy consumption per unit salt removed scales with the quotient of the voltage over the salt transport number:…”

“…Opinions vary as to the level of total dissolved solids (TDS) that can be tolerated [10] and a complete understanding of issues of chemical compatibility remains elusive [2]. There is evidence that, with improved chemical formulations, high salinity produced waters may be reused without desalination, particularly in the formulation of fluids for slickwater processes [11][12][13][14][15][16] (processes with high volume flow rates to avoid premature settling of sand, which serves to maintain fractures propped open) and to some extent for cross-linked gel fracturing processes [17] (lower volume flow rate processes employing low molecular weight guar gum based gels to ensure proppant remains suspended). However, the increase in chemical costs associated with such formulations not evident.…”

Turbulent Drag Reduction with an Ultra-High-Molecular-Weight Water-Soluble Polymer in Slick-Water Hydrofracking

“…Generally, fracturing fluids suffer different shear rates during the fracturing process. For example, a higher shear rate in excess of 3880 s −1 is observed in shale fracturing treatments [30]. In contrast, a relative low shear rate inside the fractures is ranging from 10 to 100 s −1 [31].…”

Holistic Planning Model for Sustainable Water Management in the Shale Gas Industry

“…Direct reuse of flowback water has been possible because of the development of salt-tolerant friction reducers. ,, Previous friction reducers were not compatible with salt-water; therefore, they were not able to control friction pressure losses and associated pump pressure. Direct reuse in drilling the subsequent wells is currently the most popular option because of its operational simplicity for contractors .…”