High-Temperature Fracturing Fluids Research Articles

Research Progress of High Temperature Resistant Fracturing Fluid System

China has made significant progress in the efficient exploration and development of deep-seated oil and gas wells. Reservoir reformation, as the core tool of high-temperature deep-seated exploration and development, puts forward a strong demand for fracturing fluids. The ultra-high temperature fracturing fluid system developed in my country is mainly divided into two types: ultra-high temperature guar gum fracturing fluid and ultra-high temperature synthetic polyacrylamide fracturing fluid. The high temperature resistant fracturing fluid system is mainly composed of high temperature resistant thickener, high temperature resistant crosslinking agent and temperature stabilizing additives and other additives. Based on indoor research and a large amount of literature, this article summarizes the research and application of high temperature resistant fracturing fluid system, high temperature resistant thickener, high temperature resistant crosslinking agent and temperature stabilizing additives in my country in recent years, and pointed out the shortcomings and limitations of the high-temperature fracturing fluid, the technical direction of the development of high-temperature resistant fracturing fluid technology is proposed.

Reduced-Polymer-Loading, High-Temperature Fracturing Fluids by Use of Nanocrosslinkers

Summary In the quest to discover more natural-gas resources, considerable attention has been devoted to finding and extracting gas locked within tight formations with permeability in the nano- to microdarcy range. The main challenges associated with working in such formations are the intrinsically high-temperature and high-pressure bottom conditions. For formations with bottomhole temperatures at approximately 350–400°F, traditional hydraulic-fracturing fluids that use crosslinked polysaccharide gels, such as guar and its derivatives, are not suitable because of significant polymer breakdown in this temperature range. Fracturing fluids that can work at these temperatures require thermally stable synthetic polymers such as acrylamide-based polymers. However, such polymers have to be used at very-high concentrations to suspend proppants. The high-polymer concentrations make it very difficult to completely degrade at the end of a fracturing operation. As a consequence, formation damage by polymer residue can reduce formation conductivity to gas flow. This paper addresses the shortcomings of the current state-of-the-art high-temperature fracturing fluids and focuses on developing a less-damaging, high-temperature-stable fluid that can be used at temperatures up to 400°F. A laboratory study was conducted with this novel system, which comprises a synthetic acrylamide-based copolymer gelling agent and is capable of being crosslinked with an amine-containing polymer-coated nanosized particulate crosslinker (nanocrosslinker). The laboratory data have demonstrated that the temperature stability of the crosslinked fluid is much better than that of a similar fluid lacking the nanocrosslinker. The nanocrosslinker allows the novel fluid system to operate at significantly lower polymer concentrations (25–45 lbm/1,000 gal) compared with current commercial fluid systems (50–87 lbm/1,000 gal) designed for temperatures from 350 to 400°F. This paper presents results from rheological studies that demonstrate superior crosslinking performance and thermal stability in this temperature range. This fracturing-fluid system has sufficient proppant-carrying viscosity, and allows for efficient cleanup by use of an oxidizer-type breaker. Low polymer loading and little or no polymer residue are anticipated to facilitate efficient cleanup, reduced formation damage, better fluid conductivity, and enhanced production rates. Laboratory results from proppant-pack regained-conductivity tests are also presented.

Field Study of a New High-Temperature Fracturing Fluid in South Texas

Summary Extensive field development of a new fracturing system incorporating a temperature-delayed crosslinker was undertaken over a 15-month period in south Texas. Treatments performed at depths from 7,500 to 17,100 ft [2290 to 5210 m] revealed that the new fluid has properties superior to those of high-temperature systems that use conventional organometallic crosslinkers. Treated formations include the Wilcox, Frio, and Vicksburg. The use of this new fluid has resulted in lower and more consistent friction pressures. Average sand concentrations have been increased. A significant decline in the occurrence of screenouts has been observed.