Application of a Zwitterionic Hydrophobic Associating Polymer with High Salt and Heat Tolerance in Brine-Based Fracturing Fluid

Abstract

ZID16PM, a zwitterionic hydrophobic associating polymer, has equivalent positive and negative charges and some hydrophobic monomers with twin-tailed long hydrophobic chains. It exhibits a great heat resistance and salt tolerance to the common salt in formation brine (MgCl2, CaCl2, NaCl, and KCl), which is attributed to its anti-polyelectrolyte effect and strong association force. High-salinity water (seawater or formation water) can be prepared as a fracturing fluid directly. In this paper, the formation water of the West Sichuan Gas Field is directly prepared into fracturing fluid with a concentration of 0.3% ZID16PM (Fluid-1), and the seawater of the Gulf of Mexico is directly prepared into fracturing fluid with a concentration of 0.3% ZID16PM (Fluid-2). Finally, rheological measurements, proppant suspension tests, and core matrix permeability damage rate tests for the Fluid-1 and Fluid-2 are conducted. Results show that after 120 min of shearing at 140 and 160 °C, respectively, the viscosity of Fluid-1 remains in the range of 50–85 mPa·s, and the viscosity of Fluid-2 remains in the range of 60–95 mPa·s. And the wastewater produced by an oilfield in Shaanxi, Xinjiang, and Jiangsu are also prepared into fracturing fluids with a concentration of 0.3% ZID16PM, the viscosity of these fracturing fluids can remain 32, 42, and 45 mPa·s, respectively, after 120 min of shearing at 160 °C. All results demonstrate that the polymer ZID16PM displays prominent performance in fracturing fluids.

Experimental Study on High-Performers Quaternary Copolymer Based on Host–Guest Effect

“…Inorganic salt has a negative influence on the polymer solution viscosity, especially the divalent ones, such as Ca 2+ and Mg 2+ [ 34 ]. As shown in Figure 14 a, the viscosity change of the HGP solution was more pronounced than those of the HP-T and GP-T solutions.…”

Salinity‐ and Heat‐Tolerant VES (Viscoelastic Surfactant) Clean Fracturing Fluids Strengthened by a Hydrophobic Copolymer with Extremely Low Damage

“…It can be seen from the rheological tests in the figure above that the temperature resistance of these four surfactants is not good, and their fracturing fluid systems can only be used at a temperature below 100°C. Therefore, this paper continues to study the influence of temperature-resistant hydrophobic associating polymer ZID 16 PM [53] as an adjuvant on the improvement of the temperature resistance of fracturing fluid systems. Through using 2 wt % surfactant and 0.05 wt % hydrophobic associating polymer, the fracturing fluid systems are directly prepared with the formation water from the Tahe Oilfield, and their rheological properties are tested.…”

“…In the initial stage, the proppant was stably dispersed, suspended in the fracturing fluid, and then heated in a drying oven, and the proppant began to settle. We recorded the settling velocity (the distance that the particles fall in the measuring cylinder per unit time at a fixed temperature when settling in a stationary fluid [53] ) of the proppant and compared it with the proppant suspension performance of traditional guar gum and linear glue. [65] The relevant datasets are shown in Table 4.…”

“…The results are shown in Table 5. Compared with guar gum and ordinary polymer (linear glue), [53] they have lower core damage rates and meet SY/T 6376-2008 "General technical requirements for water-based fracturing fluids". [55] At the same time, after adding hydrophobic associating polymer, the core damage rates will increase, but they all can meet the demand of clean fracturing fluids.…”

“…[7,[49][50][51][52] The lack of fresh water resources is a considerable problem affecting the application of clean fracturing fluids. [53] Thus, we further investigated the possibility of preparing these four surfactants directly into fracturing fluids using formation-produced water or high-salinity water. And the influence of a small amount of hydrophobically associating polymers on the temperature resistance of fracturing fluid systems was also studied.…”