Abstract
Hydraulic fracturing using water-soluble polymers has been extensively used to enhance the productivity of oil and gas wells. However, the production enhancement can be significantly impaired due to polymer residue generated within the proppant pack in the created fractures. This work describes an approach to establish a suitable fracturing fluid cleanup process by characterizing broken polymer residues generated from the use of different gel breaker types. Commonly used gel breakers such as inorganic oxidizers (bromate and persulfate salts), specific enzymes, and acids were evaluated in this work. The influence of each gel breaker was examined using High-Pressure/High-Temperature (HP/HT) rheometer, aging cells, zeta potential, Gel Permeation Chromatography (GPC), and Environmental Scanning Electron Microscope/Energy Dispersive X-ray Spectroscopy (ESEM/EDS). Experiments were performed on a carboxymethylhydroxypropyl guar (CMHPG) fracturing fluid at temperatures up to 300 °F. The developed GPC methodology showed that the size of the broken polymer chains was mainly dependent on the type of gel breakers used. Moreover, laboratory tests have revealed that some gel breakers may negatively influence the performance of polymeric clay stabilizers. Additionally, this work showed damaging precipitations that can be generated due to the interactions of gel breakers with H2S.
Highlights
Hydraulic fracturing treatments have been used as one of the main stimulation techniques to enhance the productivity of low-permeability oil and gas formations [1,2,3]
The fracturing fluid consisted of carboxymethylhydroxypropyl guar (CMHPG) polymer, a high-temperature stabilizer, and a dual crosslinker, which were all provided by a service company and used as received, Table 1
This work utilized gel permeation chromatography to measure the size of broken polymer
Summary
Hydraulic fracturing treatments have been used as one of the main stimulation techniques to enhance the productivity of low-permeability oil and gas formations [1,2,3]. These treatments have been applied in relatively shallow to deep hot formations with depth more than 20,000 ft [4,5]. They have been successfully applied using water salinities up to seawater and even produced water [6,7,8]. Oil-based fracturing fluids are gasoline gelled with aluminum carboxylates, soaps, viscous refined oils, phosphate
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