Evaluation of CO2-triggered and thermo-responsive gels for heterogeneous oil formations

CO2-responsive gels

“…400 A combination of multiple stimuli, e.g. , thermo- and CO 2 -responsive gels, 354,355,401 is particularly advantageous because it often widens the controllable range or improves the degree of precision of a given system.…”

“…CO 2 dissolution only offers a narrow pH window (mildly acidic to neutral), and this may ultimately pose limitations on the application. 400 A combination of multiple stimuli, e.g., thermo-and CO 2 -responsive gels, 354,355,401 is particularly advantageous because it often widens the controllable range or improves the degree of precision of a given system.…”

“…The gels were categorised according to the particle size of the gel (nanogels, microgels, aerogels, macrogels, and CO 2 -induced self-assembled gels), with the most explored gels being CO 2induced self-assembled gels (33 publications) and the least studied being CO 2 -responsive aerogels (only 3 publications). All the gels have been investigated for emerging applications, 381 Sun et al 383 Du et al 313,389 Liu et al 390 Xiong et al 369 Li et al 342 Wu et al 391 Luo et al 392 Nguele et al 355 Raj et al 344 Wu et al 393 Pu et al He et al 299 Lin et al 283 Yue et al 327,395,396 Xu et al 284 Nagai et al 353 Zhang et al 349 Zhang et al 88 Nagasawa et al 330 4 Change in pore size/permeability of gel particles Controlled release of contents from gel particles Lei et al 48,287 Satav et al 334 Han et al 274 5 Destruction and reconstruction of intermolecular bonds…”

Synthesis and Performance Evaluation of an Organic/Inorganic Composite Gel Plugging System for Offshore Oilfields

“… 7 − 11 The commonly used plugging agents for offshore reservoirs can be classified into organic gels or inorganic gels. The organic plugging agents include chromium(III) polymer gel, 12 , 13 phenolic gel, 14 starch-acrylamide gel, 15 , 16 thermoresponsive polymer gel, 17 amphiphilic copolymers, 18 and so on. Inorganic gels primarily refer to the gels formed by the reaction between cations and various inorganic salts.…”

“…Bohai oilfield is the largest offshore oilfield in China, and it has been developed by chemical flooding for tens of years. − In recent years, it has been found that oil production in the medium- and low-permeability reservoir layers is unsatisfactory due to the existence of large fluid flow channels after the long-term scouring process of the oil displacement agent. − To enhance the oil recovery in Bohai oilfield, it is important to find effective plugging agents to plug the dominant fluid flow channels to improve the swept volume of the oil displacement agent. − The commonly used plugging agents for offshore reservoirs can be classified into organic gels or inorganic gels. The organic plugging agents include chromium­(III) polymer gel, , phenolic gel, starch-acrylamide gel, , thermoresponsive polymer gel, amphiphilic copolymers, and so on. Inorganic gels primarily refer to the gels formed by the reaction between cations and various inorganic salts. − In general, organic gels can form a three-dimensional network structure by the gelling reaction in the porous medium, thus plugging the dominant fluid flow channels and improving the reservoir heterogeneity, − while the inorganic gel normally has stronger rigidity and retention in the reservoir, thus effectively reducing the reservoir permeability after its utilization.…”