The Synergetic Impact of Anionic, Cationic, and Neutral Polymers on VES Rheology at High-Temperature Environment

Abstract

Hydraulic fracturing operations target enhancing the productivity of tight formations through viscous fluid injection to break down the formation and transport proppant. Crosslinked polymers are usually used for desired viscoelasticity of the fracturing fluid; however, viscoelastic surfactants (VES) became a possible replacement due to their less damaging impact. To design a fracturing fluid with exceptional rheological and thermal stability, we investigated mixing zwitterionic VES with carboxymethyl cellulose (CMC), hydroxyethylcellulose (HEC), or a poly diallyl dimethylammonium chloride (DADMAC) polymers. As a base fluid, calcium chloride (CaCl2) solution was prepared with either distilled water or seawater before adding a polymer and the VES. A Chandler high-pressure, high-temperature (HPHT) viscometer was used to conduct the viscosity measurements at a shear rate of 100 1/s. It has been found that adding 1% CMC polymer to 9% (v/v) VES increases the viscosity more compared to 10% (v/v) VES at reservoir temperatures of 143.3 °C. On the other hand, adding only 1.0% of HEC to 9% (v/v) VES doubled the viscosity and proved more effective than adding CMC. HEC, nevertheless, reduced the system stability at high temperatures (i.e., 148.9 °C). Adding DADMAC polymer (DP) to VES increased the system viscosity and maintained high stability at high temperatures despite being exposed to saltwater. CaCl2 concentration was also shown to affect rheology at different temperatures. The improved viscosity through the newly designed polymer can reduce chemical costs (i.e., reducing VES load), making it more efficient in hydraulic fracturing operations.

Effect of Seawater Ions on Polymer Hydration in the Presence of a Chelating Agent: Application to Hydraulic Fracturing

“…Polymer-based viscosity-modifying agents such as poly (acrylic acid), poly­(vinyl alcohol), guar gum and its derivatives, cellulose, and poly­(acrylamide) are widely utilized. The number of functional groups, their location, and polymer molecular weight determine the characteristics of the polymer . Among the guar gum derivatives, hydroxypropyl guar (HPG) and carboxymethyl hydroxypropyl guar (CMHPG) are extensively used in hydraulic fracturing due to the ease of hydration and minimum residue content .…”

“…The number of functional groups, their location, and polymer molecular weight determine the characteristics of the polymer. 7 Among the guar gum derivatives, hydroxypropyl guar (HPG) and carboxymethyl hydroxypropyl guar (CMHPG) are extensively used in hydraulic fracturing due to the ease of hydration and minimum residue content. 8 The guar derivatives can be crosslinked to generate very high viscosity at a low concentration.…”

Investigating Effects of Chelating Agents on Viscoelastic Surfactant Flooding at the Pore Scale Using Micromodels

“…The scarcity of fresh water in the gulf area made using seawater in chemical flooding operations an advantage because the cost of water softening is saved. Also, the presence of the free ions in the solution may cause chemical precipitation, viscosity reduction, and degradation. , Divalent ions will bond with the VES to form wormlike micelles, which increase the viscosity; however, the extra amount of the free ions will negatively affect the viscosity and the IFT. − Chelating agents can chelate the ions in the solution and neutralize their effect on viscosity and IFT. Many applications have been presented in the literature for the use of chelating agents in the petroleum industry, such as filter cake removal, carbonate dissolution to alter the wettability and enhance the permeability, , and prevention of solid precipitation and fine migration as well as IFT reduction…”

Preparation and evaluation of acryloyl morpholine modified emulsion fracturing fluid thickener with high temperature resistance and salt resistance

“…The fracturing fluid is critical in creating the designed fracture geometry and controlling the proppants‐carrying efficiency, thus, proper selection of the fracturing fluid is significant in hydraulic fracture treatment 1–4 . Among them, water‐based fracturing fluid is widely used in major oil and gas fields in China due to its high viscosity, low friction, and strong sand suspension capacity 5–8 . Water‐based fracturing fluid is a kind of polymer gel material, which uses crosslinking agent and water‐soluble polymer thickener to make the polymer with linear structure coexisting with network structure.…”

“…[1][2][3][4] Among them, water-based fracturing fluid is widely used in major oil and gas fields in China due to its high viscosity, low friction, and strong sand suspension capacity. [5][6][7][8] Water-based fracturing fluid is a kind of polymer gel material, which uses crosslinking agent and watersoluble polymer thickener to make the polymer with linear structure coexisting with network structure. As the main additive of water-based fracturing fluid, thickener can improve the viscosity, sand carrying and filtration loss properties of fracturing fluid, guar gum and its derivatives and polyacrylamide polymers are common thickeners of fracturing fluids.…”