... as composites has been introduced as a promising family of hydrogel materials due to the ability to absorb huge volumes of water while maintaining strong mechanical strength and high damping and flexibility properties. The clay particles are expected to act as extra crosslinking sites throughout the polymer...

... and by determining their role in maintaining structural strength. Several PPG hydrogels were prepared by varying the concentrations of polyacrylamide and chromium triacetate [Cr(OAc) 3 ] as copolymer and crosslinker, respectively, using a central composite design. The characterization of these hydrogels...

... on crosslinking reactions between polymers and crosslinkers. Breaker technologies such as oxidizers, enzymes, fluoride compounds, oxides, vitamins, and decrosslinking agents are used to break the crosslinked polymer-based gels. These materials are added as components of the initial fracturing-fluids recipe...

... fracturing fluid that combines a next-generation boron crosslinker with a new hydroxypropyl guar (HPG) to be crosslinked with 40 to 60% less polymer than used in conventional borate-crosslinked fluids. For this fluid, HPG loadings in the range of 8 to 12 lbm/1,000 gal were used to produce boron-crosslinked...

... was diminished significantly). Another challenge is the pressure-dependent behavior of borate-crosslinked gels, where the viscosity was found to drop significantly under high pressures. Also, in high-temperature reservoirs (>350°F), it is very challenging to design a fluid that can sustain enough viscosity...

.... The gelation performance can be adjusted by changing the concentration of hydrolyzed polyacrylamide (HPAM), crosslinker, and ammonium salt. Over the last decades, the working behavior of a gel system in a reservoir has been evaluated simply through the gelation-performance bottle test and the effectiveness...

...-molecular-weight synthetic polymer) and a crosslinker. Measurements on the gelant systems’ viscosity showed that the base sodium silicate system has a low, water-like, viscosity with a Newtonian behavior. This provides significant benefits for matrix treatment, but higher gelant viscosities may be required...

...Magnus Legemah; Frances De Benedictis; Nigatu Workneh; David Smith; Hoang Le; Hong Sun; Qi Qu; Mickey Moulton Summary Guar-based fracturing fluids are the most commonly used fluids in reservoir stimulation. To provide high viscosity, borate-crosslinked gels are preferred for their ability to heal...

... for wells at temperatures of less than 300°F (148.9°C). To minimize the damage associated with this class of polymers, the industry has attempted several approaches. These included the use of a lower polymer concentration in formulating these fluids and alteration of the crosslinker chemistry so that one...

... crosslinking on the reaction rate was examined. Coreflood experiments were conducted at 250°F using two different rates of injection (2 and 10 cm 3 /min), and the core samples were imaged using a computed-tomography (CT) scan technique after each coreflood experiment. Increasing formic acid concentration...

... (1.5-in. diameter and 20-in. length) at high temperatures and pressures. Propagation of the acid, polymer, and crosslinker inside the long cores was examined in detail. Samples of the core effluent were collected, and the concentrations of calcium, crosslinker, and acid were measured. Permeability...

... acids that are based on polymers should be prepared using low salinity waters and used at low HCl concentrations (3 to 5 wt% HCl). Initial spending of the live acid, during leakoff and wormholing, produces a rise in pH to a value of above approximately 2, which initiates crosslinking of the polymer...

... production from hydrocarbon wells, with varying degrees of success. For approximately eight years, a polymer gel system based on an acrylamide/t-butyl acrylate copolymer (PAtBA) crosslinked with polyethyleneimine (PEI) has been used successfully for various water shutoff applications. This article describes...

.... The crosslinker was then added to the tank and mixed for 30 seconds. All the fluid was then pumped at 10 bbl/min from the 50-bbl tank through the curved coiled-tubing unit and the straight tubing. The first 30 bbl of fluid was used to flush the system and pumped to a waste tank. The remaining 20 bbl of fluid...

...P. C. Harris; S. J. Heath Summary This paper presents a study of hydration, crosslinking, and rheological properties of 15- to 25-lbm/1,000-gal optimized borate-crosslinked guar fluids. Hydration and crosslinking properties of fluids were measured in a new turbulent flow-loop viscometer to simulate...

...R. H. Lane Summary This paper describes field experience with low- and high-molecular-weight partially hydrolyzed polyacrylamide (PHPA) polymers crosslinked with Cr(III) carboxylate species. On the basis of that experience, the paper addresses successes and limitations in terms of downhole...

...K. E. Cawiezel; J. L. Elbel Summary This paper describes a delayed-crosslink activator system for borate fracturing fluids that allows crosslinking rates to be controlled to give low friction pressure in the wellbore. Data from laboratory development, full-scale friction tests, and fracturing...

... distribution, fluid rheology, and characterization of water-solubilized RCP organic compounds. The gel containing the appropriate additives was mixed and hydrated in a blender. RCP was slurried into the gel at a concentration of 8 lbm/gal. The crosslinker was added, and stirring continued for 30...

...-loop viscometer over a temperature range of 80 to 300°F [27 to 149°C]. Rapid and complete base-gel hydration required proper pH control and high mixing energy. Oil-based polymer slurries allowed rapid hydration rates sufficient to achieve performance from a crosslinked fluid prepared during...

...D. W. Walser 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...