CO2-triggered gelation for mobility control and channeling blocking during CO2 flooding processes

Abstract

CO 2 flooding is regarded as an important method for enhanced oil recovery (EOR) and greenhouse gas control. However, the heterogeneity prevalently distributed in reservoirs inhibits the performance of this technology. The sweep efficiency can be significantly reduced especially in the presence of ''thief zones''. Hence, gas channeling blocking and mobility control are important technical issues for the success of CO 2 injection. Normally, crosslinked gels have the potential to block gas channels, but the gelation time control poses challenges to this method. In this study, a new method for selectively blocking CO 2 channeling is proposed, which is based on a type of CO 2 -sensitive gel system (modified polyacrylamide-methenamine-resorcinol gel system) to form gel in situ. A CO 2 -sensitive gel system is when gelation or solidification will be triggered by CO 2 in the reservoir to block gas channels. The CO 2 -sensitivity of the gel system was demonstrated in parallel bottle tests of gel in N 2 and CO 2 atmospheres. Sand pack flow experiments were conducted to investigate the shutoff capacity of the gel system under different conditions. The injectivity of the gel system was studied via viscosity measurements. The results indicate that this gel system was sensitive to CO 2 and had good performance of channeling blocking in porous media. Advantageous viscosity-temperature characteristics were achieved in this work. The effectiveness for EOR in heterogeneous formations based on this gel system was demonstrated using displacement tests conducted in double sand packs. The experimental results can provide guidelines for the deployment of the CO 2 -sensitive gel system for field applications.

Synthesis, characterization and evaluation of polyacrylamide graft starch/clay nanocomposite hydrogel system for enhanced oil recovery

“…Normally, the capacity of the gel system for water shutoff or water shutoff efficiency can be evaluated by the reduction in permeability of the sand pack after the gel treatment (Chen et al 2015;Kang et al 2015;Karimi et al 2014;Li et al 2016;You et al 2015), which is defined as:…”

CO2/N2-Responsive Nanoparticles for Enhanced Oil Recovery During CO2 Flooding

“…The responsive process is illustrated in Figure 6B. The responsivity tests showed that the tertiary amine groups could interact with CO 2 /N 2 , which could be used to control the properties of nanofluid such as in CO 2 -triggered switchable surfactants reported by Liang et al (2011), CO 2 -sensitive foams researched by Li et al (2016), or CO 2 -triggered gelation proposed by Li et al (2017). However, this paper intends to control the stability of nanoparticles in nanofluid via CO 2 /N 2 response.…”

“…The conventional methods utilized to mitigate CO 2 gas channeling are gel injection, polymer injection, and foam injection. Li et al (2016) proposed the modification of polyacrylamide-methenamine-resorcinol gel agents to block CO 2 channeling. Sun et al (2016) reported that aqueous foams stabilized by partially hydrophobic SiO 2 showed better CO 2 mobility control performance.…”

Polyacrylamide hydrogel application in sand control with compressive strength testing

“…In the bottle test, the time of hydrogel formation (gelation time) is measured, while the hydrogel is not under stress or shear (Akhlaghi Amiri and Hamouda 2014;Salimi et al 2014). Generally, the bottle test is a simple and fast method to evaluate the gelation time, gel strength, heat resistance, syneresis time (Karimi et al 2016;Li et al 2016), and to determine the hydrogel composition of cross-linker and polymer (Adewunmi et al 2017). The samples were transferred into high thermal resistance glass tubes (70 mL, Simax, Italy) and were kept at 90°C in an UN55 oven (Memmert, Germany).…”