Insights on Potential Formation Damage Mechanisms Associated with the Use of Gel Breakers in Hydraulic Fracturing

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.

Review of Developments in Nanotechnology Application for Formation Damage Control

“…A large volume of proppants is pumped into the formation to enhance transportation of shale gas from the formation to the wellbore in commercial quantities. − Such production requires the complex network of artificial fractures to have sufficient conductivity to sustain the whole period of production . Unfortunately, the techniques for transporting and placing proppants in the formation to hold the fractures exhibit formation damage near the fracture surface that affects fracture packing. − Many mechanisms impair the fracture conductivity during the process of fracturing. ,, These include proppant embedment, closure stress effect, , proppant crushing, , cyclic stress, fine migration, proppant pack diagenesis, , and the blockage caused by the gel residue in the proppant pack and gel filter cake at the fracture face. , …”

Formation-Damage Mechanism and Gel-Breaker-Free Drill-In Fluid for Carbonate Reservoir

“…As a result, the reservoir formation permeability will also be reduced; it is necessary, therefore, to use gel-breaker solution to destroy and remove the filter cake after drilling operations [ 25 , 26 , 27 ]. Most commonly used gel breakers are acidic or strong oxidizing substances, which increase the operating costs and present safety risks [ 28 , 29 , 30 ]. Therefore, it was necessary to study a polymeric drill-in fluid that did not require gel-breaker treatment, in order to improve the safety and efficiency of drilling and completion operations.…”

Specific-Ion Effects Unveil a Route for Modulating Oxidatively Triggered Acid Systems for Reservoir Applications

“…Oxidizing agents are ubiquitous material additives in the upstream sector of the oil and gas industry. Historically, they are used as biocide agents and viscosity modifiers in hydraulic fracturing fluids. − More recently, a new type of reactive fracturing fluid was proposed, and its chemical properties enable oxidative degradation of kerogen, a polymer-like intertwined organic material, present in unconventional source rock. This unique reactivity allows for increased hydrocarbon recovery by physically cracking the organic matter and opening conductive channels to enable the flow of hydrocarbons. , Another unique use of oxidizers for potential reservoir stimulation applications is in situ acid generation where bromate (BrO 3 – ) can selectively oxidize ammonium (NH 4 + ) to liberate acid (H + ) yielding a series of inorganic acids …”