A Crosslinkable Synthetic Polymer System for High-Temperature Hydraulic Fracturing Applications

Abstract

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.

Hydraulic Fracturing Under Extreme HPHT Conditions: Successful Application of a New Synthetic Fluid in South Texas Gas Wells

“…In comparison, the synthetic fluid at the same polymer concentration has a greater delay in the onset of crosslinking and only a slow decline in viscosity upon reaching the test temperature. The crosslinking onset temperature of the synthetic fluid is adjustable over the range of 100 to 270°F (38 to 132°C) by varying the amounts of delayed crosslinker (XL1) and activator (XLA) (Holtsclaw and Funkhouser 2009). One concern with using a synthetic fluid is the ability to break the fluid and establish good fracture conductivity.…”

“…The polymer developed for high-temperature fracturing is a random terpolymer of acrylamide, AMPS, and acrylate synthesized by free-radical polymerization ( Fig. 1) Norman 2003, 2006;Holtsclaw and Funkhouser 2009). Although shown in the acid form, the polymer is partially neutralized for use in the fracturing fluid.…”

Laboratory Evaluation of a Low pH and Low Polymer Concentration Zirconium-CMHPG Gel System for Hydraulic Fracturing

“…The delay performance is desirable even at a pH as low as 2.0, which could be attributed to the strong original bonds formed by the ligands (lactate and ethylene glycol) to zirconium center. (5) The zirconium-CMHPG gel system has two potential gelation mechanisms: covalent bonding and hydrogen bonding. (6) A uniform and compact 3D network structure with a grid size of 16.4 to 27.3 μm is generated within the gel, which can further improve the thermostability and acid-resistance of the fluid.…”

“…3,4 The properties of fracturing fluid are very significant in the creation and propagation of the fracture. With the advancement of the industry, a batch of novel fracturing fluids has emerged, such as polyacrylamide-based polymer, 5,6 slick water, 7,8 viscoelastic surfactant, 9−14 and energized fluid. 15−18 However, due to either their high cost, weak thermal stability, high leak-off coefficient, or poor proppant-transport capacity, guar gum and its derivativesbased polymer gels are still the most commonly used fluids in modern hydraulic fracturing operations.…”

A Review of Advanced Molecular Engineering Approaches to Enhance the Thermostability of Enzyme Breakers: From Prospective of Upstream Oil and Gas Industry

“…The reduction in MW causes a reduction in the viscosity of the gel. The commonly used oxidizers as viscosity reducers are sodium persulfate, ammonium persulfate, and potassium persulfate [9] In acids as gel breakers, weak acids are used as a breaker including tannic and citric acid. The acids lower the pH of the liquid solution and decrease the viscosity.…”