Modeling the spontaneous imbibition of non-Newtonian fluids into the fractal porous media of tight reservoirs

Viscoelastic Effects on Spontaneous Imbibition in Unsaturated Porous Membranes of Complex Shapes

“…Having said this, it should be conceded that in the real world, other parameters may have concurrently contributed to the discrepancy. For example, it can be argued that the air trapped in the dead-end pores of the consolidated sandstone used in their study may have affected the permeability dynamics of the wetting liquid; see Qin et al 28 To this should be added the fact that, although the names of the polymer solutions used in the tests by Zhu et al 9 have not been disclosed, they mentioned that their polymer solutions were typical of those used as pusher fluids, which means that perhaps they used PEO, PAA, CMC, or XC additives for preparing their polymer solutions. When dissolved in water, at equilibrium, the radius-of-gyration of these polymer chains is less than one micron.…”

“…It will be shown that, in two-dimensional flows, the viscoelastic Richards model obtained this way is in the form of three coupled partial differential equations (with two of them being highly nonlinear), which must be solved numerically. The performance of the viscoelastic Richards equations (VRE) developed in this work will be tested against limited imbibition data reported by Zhu et al 9 for a typical shear-thinning polymer solution.…”

“…Asadi et al included the gravitational term in their generalized Richards equation (developed for predicting imbibition of power-law fluids) and reached to the conclusion that gravity played no significant role simply because the height of the sandstone core sample used in the tests was just 5 cm. So, as stands, the main cause of the discrepancy in the work of Zhu et al remains unexplored. Interestingly, recent experimental data reported by Gorthi et al for capillary rise of CMC polymer solutions (modeled as power-law fluid) in a glass capillary tube exhibits a similar discrepancy between their theoretical model and the experimental results.…”

“…It is one of the main objectives of the present work to show that by including an elastic term in the two-phase Darcy’s law, the experimental imbibition data reported by Zhu et al can be closely recovered although it should be conceded that, in real world, other mechanisms might be concurrently responsible for the discrepancy mentioned above. For example, polymer macromolecules adsorbed at the surface of the grains of a porous material or stuck in the smaller-sized pores can easily affect the wetting dynamics of the displacing fluid and/or the permeability of the medium in a negative sense.…”

Effects of Microscopic Pore Structures on the Spontaneous Imbibition of Longmaxi Shale

“…A soaking process, referring to an extended shut-in period, is commonly reported in shale gas wells after fracturing treatment. Theoretical and experimental studies have demonstrated that spontaneous imbibition (SI) plays an important role in the distribution of fracturing fluids during the soaking process (e.g., refs − . Additionally, studies have demonstrated that imbibition during the soaking process can improve the production performance of shale gas wells. − Consequently, studying the SI behaviors is of great significance to improve the understanding of gas recovery from shale reservoirs.…”