Summary A new hydraulic-fracturing fluid has been developed that is capable of reaching fluid service temperatures up to 232°C. This fracturing fluid technology uses a synthetic polymer that is crosslinkable with metal ions to generate high viscosity. The synthetic-polymeric fracturing gel overcomes the thermal limitations of traditional guar and derivatized guar-based fracturing fluids. Several advancements have been made in the development of this technology to maximize the efficiency of crosslinking and to give an effective breaking profile, resulting in good laboratory gel cleanup in the proppant pack. Research efforts have yielded a fracturing fluid with good fluid stability at high temperatures to create better proppant transport and placement in these most-demanding environments. An integral part of this fluid is a crosslinking system that can be "tuned" for crosslinking onset from 38 to 138°C, allowing for optimization for particular well conditions. The crosslinking system allows the treatment schedule to be tailored to the targeted well to help minimize frictional pressure loss. An efficient and effective oxidative-breaker package has been developed to give a controlled rheological break for the synthetic fluid and provide good regained conductivity data. The new, high-temperature fracturing technology provides a new tool to stimulate hotter, deeper hydrocarbon resources to help maximize hydrocarbon recovery. This fracturing-fluid system has been applied successfully in south Texas at temperatures approaching 232°C. Laboratory rheological data that demonstrate fluid stability, crosslinking performance, and controlled fluid breaks are presented. Dynamic fluid-loss and regained-conductivity data are also presented to illustrate fluid cleanup in proppant packs.

The industry is seeing significant pressure from regulatory bodies concerning the chemicals that comprise typical fracturing fluids. It has long been the belief of the industry that to obtain the best performance of a fracturing fluid, it is necessary to use certain chemicals in fracturing-fluid formulations. However, this paper clearly illustrates that a fluid comprised solely of components sourced from the food industry can excel in maintaining proppant-transport performance. This paper focuses on the proppant transport of a fracturing fluid that is comprised solely of components sourced from the food industry and approved for direct addition to foods as governed by the Code of Federal Regulations Title 21 (CRF 21). The proppant-transport capabilities of this fluid are compared to a borate-crosslinked galactomannan, a viscoelastic-surfactant (VES) fluid, and a linear-gelled system. The results illustrate that proppant-transport performance does not need to be sacrificed when using a fluid system comprised of components sourced from the food industry. The ability to carry proppant into the fracture is one of the most fundamental attributes necessary for a successful fracturing fluid. This paper provides an evaluation of four types of fluids currently used as gelled fracturing fluids, employing five different methods to measure their ability to transport and support proppant. The methods used in the evaluation include traditional steady-shear viscosity, small-amplitude oscillation rheology, flow-through-a-slot model, a slurry viscometer, and static settling results. The results show clearly that the testing methods and protocols do not necessarily agree on the best performance of a fluid system; a comprehensive examination of the limitations and benefits of each are examined. Some of the gels tested showed good proppant support under static conditions, while others showed good transport under flow conditions. The crosslinked gel that was sourced solely from the food industry showed a dramatic difference in that it was able to support proppant under static- and dynamic-shear conditions, leading to superior proppant-transport performance using the five test methods.

A new hydraulic fracturing fluid has been developed that is capable of stimulating high pressure/high temperature (HPHT) wells at 450°F without the need for cooling preflushes. Good viscosity at fluid temperatures as high as 450°F gives the synthetic fluid the potential to provide substantially better proppant placement than polysaccharide-derivative gels. The gelling agent is based on a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, and acrylic acid that can be crosslinked with zirconium. The crosslink onset temperature can be varied over the range of 100 to 280°F, allowing optimization for particular well conditions. A delayed acting oxidizing breaker can be added to accelerate the gel's degradation, allowing rapid flowback and early production. The gelling agent is provided to the wellsite as a liquid-gel concentrate that is designed to be mixed and pumped with conventional fracturing equipment and procedures.This paper discusses the laboratory testing, treatment design, and job execution leading to the successful hydraulic fracturing of two South Texas gas wells at depths of 23,300 and 18,900 ft with bottomhole static temperatures of 450°F and 433°F, respectively. The jobs were pumped as designed, with 190,000 lbs. of high-strength, resin-coated proppant placed in each zone at concentrations up to 9 lb/gal. Average treating pressures were 13,100 and 11,250 psi with slurry rates of 21 and 25.7 bbl/min, respectively. Cleanup was rapid, with gas flowing to the sales line the day after the treatment at a rate in excess of 4,000 MCF/D; in the case of the second well.

A new hydraulic fracturing fluid has been developed that is capable of reaching fluid-service temperatures up to 450°F (232°C). This fracturing-fluid technology uses a synthetic polymer that is crosslinkable with metal ions to generate high viscosity. The synthetic polymeric fracturing gel overcomes the thermal limitations of traditional guar and derivatized guarbased fracturing fluids. Several advancements have been made in the development of this technology to maximize the efficiency of crosslinking and to give an effective breaking profile, resulting in excellent gel cleanup in the proppant pack. Research efforts have yielded a fracturing fluid with good fluid stability at high temperatures to create better proppant transport and placement in these most-demanding environments.An integral part of this fluid is a crosslinking system that can be "tuned" for crosslinking from 100 to 280°F (38 to 138°C). The crosslinking system allows the treatment schedule to be tailored to the targeted well to help minimize friction pressure. An efficient and effective oxidative-breaker package has been developed to give a controlled rheological break for the synthetic fluid, and provides good retained conductivity data. The new, high-temperature fracturing technology provides a new tool to stimulate hotter, deeper hydrocarbon resources to help maximize hydrocarbon recovery. This fracturing-fluid system has been successfully applied in south Texas at temperatures approaching 450°F (232°C).Rheological data that demonstrates fluid stability, crosslinking performance, and controlled fluid breaks are presented. Dynamic fluid-loss and regained conductivity data are also presented to illustrate fluid cleanup in proppant packs.

This paper presents the retained conductivity results of a new environmentally focused fracturing fluid whose components are sourced from the food industry, as described in the US Code of Federal Regulations Title 21 (CFR 21) or the Generally Recognized as Safe (GRAS) affirmation process. The fluid is comprised of the following components: a low-residue polysaccharide gelling agent, a metal crosslinker, a surfactant, and a suite of breakers. The suite of breakers provides consistent fluid cleanup in retained conductivity testing in temperatures ranging from 120 to 200°F. Fracture conductivity testing was performed using a wet-gas cleanup protocol used in modeling hydraulically fractured wells.Hydraulic fracturing and the environmental effects of the chemicals involved in the fracturing process have become the subjects of public discussion. This discussion has encouraged the petroleum industry to address public concern regarding the potential environmental impact of chemicals used in fracturing. Service companies have responded by improving their current chemical portfolio and developing new environmentally focused chemical technologies. This paper describes an environmentally focused metal-crosslinked polysaccharide fluid that not only is more environmentally acceptable under the criteria described in this work, but also has little or no proppant-pack conductivity impairment, as measured by fracture conductivity testing.Wet-gas retained conductivity of 1-lbm/ft 2 20/40-mesh Ottawa sand was performed with humidified nitrogen gas flow. Retained conductivity of 84 to 100% was obtained after wet-gas cleanup for temperatures ranging from 120 to 200°F under a 2,000-psi closure stress. All conductivity tests were performed between Ohio sandstone wafers with filter-cake buildup from dynamic fluid-loss testing. Wet-gas retained conductivity was verified by a third-party laboratory. These results indicate that a fracturing fluid can be designed using defined environmental criteria based on food grade materials to provide similar performance and excellent retained conductivity.