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Oil production, enhanced oil recovery, waste disposal, and CO 2 storage applications in naturally fractured oil, gas, coalbed methane, geothermal reservoirs, and aquifers are characteristically controlled by an interaction between matrix and fracture. The correct estimation of the relative permeabilities for matrix-fracture interaction is essential in the performance analysis of such reservoirs. Conventional relative permeability measurement techniques are not suitable for this type of processes as the driving force is capillary rather than viscous. An alternative to these techniques is a pore scale modeling of the process. In this study, matrix-fracture interaction by capillary (spontaneous) imbibition was numerically simulated using the Lattice Boltzmann Method (LBM). The classical LBM algorithm was modified to add the effects of capillary characteristics such as wettability and interfacial tension. The model was validated using experiments on two -dimensional sand pack models, where the strongly water-wet model saturated with oil was exposed to water to displace oil by capillary interactions. Further, LBM simulations were used to investigate the critical parameters that have impacts on relative permeabilities such as different wettabilities, matrix boundary conditions that cause co-current interaction, and gravity (vertical and horizontal interaction). Finally, the LBM results were used to generate relative permeability curves by incorporating the algorithms based on single -phase normalization techniques. The LBM images were used to quantify the saturation values. The effects of different parameters listed above on the end points and the shape of the relative permeability curves as well as the residual oil saturation were identified. The results and observations provide qualitative and quantitative data which can be used in modeling studies for naturally fractured oil, gas, and coalbed methane reservoirs.

Microfluidic devices have acquired an important position in the field of MEMS. While the usage of mechanical components for achieving electroosmosis and electrophoresis effects can prove to be impractical and costly, alternative methods for flow control have to be explored. This paper extends the concept of obtaining a superior flow control in microchannels by using ferrofluid plugs as barriers. These plugs occlude and discharge fluid flow, thereby functioning as valves and rendering the usage of mechanical components unnecessary. A numerical simulation of a ferrofluid plug blocking fluid flow in a microchannel due to the action of a magnetic field is carried out. The relationship between ferrofluid property and the capacity to block fluid flow is studied and analyzed. Thus a new concept of flow control in a microfluidic device by the proper variation of the external magnetic field and positioning of the ferrofluid plugs has been introduced.

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