Effects of Temperature and Pressure on Spontaneous Counter-Current Imbibition in Unsaturated Porous Media

Abstract

Capillary spontaneous imbibition mainly occurs in fractured reservoirs, low permeability reservoirs, and unconventional reservoirs, simultaneously accompanied by high temperature and pressure. In this paper, we present computations of spontaneous imbibition based on the classical fractional flow theory and proposed temperature- and pressure-dependent IFT relationships. Our work emphasizes that there are some discrepancies if we evaluate the spontaneous imbibition characteristics under geological conditions based on the traditional air/water/rock system experiments in an atmospheric environment. In detail, both the increasing temperature and pressure can decrease the IFT (capillary driving force), and the pressure effect is more significant. The increasing temperature will facilitate the water intake, as the results of competition between the positive role of enhanced wetting fluidity and negative role of reduced IFT, while the increasing pressure will slow down the water propagation due to the cooperation of reduced capillary driving force and increased nonwetting flow resistance. The nonwetting (gas) phase type will also influence the imbibition process, and the distinction between the methane/water/rock system and air/water/rock system is controlled by the nonwetting phase viscosity difference at low pressure and by the IFT difference at relatively high pressure. Furthermore, for the given porous media and fluid properties, faster water saturation profile propagation for the initial water saturation range (0 < Si < 0.8) and slower movement for the initial water saturation range (0.8 < Si < 1) are observed under the reservoir conditions (P = 25 MPa and T = 358 K). The former stage is essentially controlled by the enhancing water fluidity and decreasing capillary pressure, while the latter stage will be significantly affected by the increasing viscosity of the gas phase. Overall, a correction is needed to obtain the imbibition characteristics under geological conditions based on the traditional laboratory experiment for the air/water/rock system in an atmosphere environment.

Further Investigation of Forced Imbibition in Unconventional Oil Reservoirs for Enhanced Oil Recovery

“…As discussed previously, in a water-filled fracture-rock matrix reservoir system, counter-current flow is often the only possible mean of imbibition. , In the oil-wet matrix system, the soaking pressure may not overcome the water pressure inside the matrix because of negative capillary pressure, and thus the imbibition is inhibited regardless. Whereas in the water-wet matrix, a high-pressure boundary at the two-phase contact is generated by the local capillary pressure and the externally imposed pressure.…”

“…Gupta and Civan modified Ma’s model (eq 3) by introducing the contact angle term and is expressed as The results from Zhang et al showed a negative correlation of the contact angle value to the final oil recovery, which indicates that water-wetness is beneficial to the ultimate recovery in shale. More than 30 spontaneous imbibition experiments with Wolfcamp and Eagle Ford cores were considered in this study.…”

Effects of interactions in natural gas/water/rock system on hydrocarbon migration and accumulation

“…The interface tension, and wettability are both temperature- and pressure-dependent properties. Typically, it is assumed that the temperature may significantly affect the wettability performance on rock surfaces and the interfacial tension of two-phase fluid, the pressure dependence of the wettability and interface tension is relatively weak 14 , 15 . Many researchers investigate the impact of temperature and pressure on wettability and interface tension.…”

“…The analytical algorithm will be embedded into numerical simulation software to simulate the hydrocarbon migration and accumulation process. The research on wettability in tight reservoirs mainly involves the measurement of wettability 16 , the influencing factors of wettability 17 , the influence of wettability on fluid flow 14 , and the modification of wettability 18 . However, the research on the wettability of tight reservoirs mainly focuses on reservoir evaluation 19 , oil and gas field development 9 , and improving oil and gas recovery 20 , etc.…”

Model for Interfacial Tension of Nanoconfined Lennard-Jones Fluid

“…As a prime parameter in basic formulations of many processes, including nucleation, imbibition, etc., IFT has attracted great attentions due to its wide and practical applications, such as chemical reactions, energy storage, heterogeneous catalysis, biological membrane operations, and in particular, oil and gas productions in conventional/unconventional reservoirs. − When the pore size is on the nanoscale, the confinement effect becomes strengthened, and the thermodynamic properties and interfacial behavior of nanoconfined fluids are quite different from that of the bulk counterparts. − Therefore, macroscopic expressions of the IFT cannot be employed directly, and the influences of curvature and wall–fluid interaction must be considered in theoretical studies.…”