Particle removal by two-phase filtration flow from a porous medium under wave action

The paper discusses the influence of wave action on the process of detachment and removal of particles from a porous body by a two-phase filtration flow. When modeling this process, the problem of the influence of the wave field on the force under the action of which the particles are detached from the pore walls is solved. For the first time, a pore-size distribution function is used for its solution. An expression for the critical flow velocity under wave action has been obtained. Critical frequency value of wave action depends on the capillary radius and the smaller the capillary radius is, the higher frequency is needed to enhance the effect of the action. At higher frequency of oscillation the peak of maximum change in the thickness of the sedimentary layer is shifted towards the pores of small radius. To maintain the influence of the wave field on the filtration parameters of the porous medium, the wave action should be carried out at a dynamically changing frequency range to increase the coverage of the effect of as many pores as possible. It is shown that particle removal during wave action increases due to the action of inertial forces, which reduce the influence of forces holding the particles on the pore surface.

ЭКСПЕРИМЕНТАЛЬНОЕ ОПРЕДЕЛЕНИЕ КАПИЛЛЯРНОГО РАДИУСА ЯЧЕЕК СЕТОК С ДЕФОРМИРОВАННОЙ СТРУКТУРОЙ ПЛЕТЕНИЯ

The article is devoted to the experimental study of the change in the capillary radius of cells of metal woven nets, depending on the degree of deformation of the structure of their weaving. The values of the measurements of the capillary radius of the cells are given as a function of the interlacing angle of the fibers of the nets. Recommendations are given on the possibility of using deformed nets in devices to ensure the continuity of the components of the fuel tanks of spacecraft.

The Seepage Model Considering Liquid/Solid Interaction in Confined Nanoscale Pores

Different from conventional reservoirs, nanoscale pores and fractures are dominant in tight or shale reservoirs. The flow behaviors of hydrocarbons in nanopores (called “confined space”) are more complex than that of bulk spaces. The interaction between liquid hydrocarbons and solid pore wall cannot be neglected. The viscosity formula which is varied with the pore diameter and interaction coefficient of liquids and solids in confined nanopores has been introduced in this paper to describe the interaction effects of hydrocarbons and pore walls. Based on the Navier-Stokes equation, the governing equation considered liquid/solid effect in two dimensions has been established, and approximate theoretical solutions to the governing equations have been achieved after mathematic simplification. By introducing the vortex equation, the complex numerical seepage model has been discretized and solved. Numerical results show that the radial velocity distribution near the solid wall has an obvious change when considering the liquid/solid interaction. The results consist well with that approximate mathematical solution. And when the capillary radius is smaller, the liquid and solid interaction coefficient n is greater. The liquid and solid interaction obviously cannot be neglected in the seepage model if the capillary radius is small than 50 nm when n>0.1. The numerical model has also been further validated by two types of nanopore flow tests: from pore to throat and inversely from throat to pore. There is no big difference in flow regularity of throat to pore model considering when liquid/solid interaction or not, whereas the liquid/solid interaction of pore to throat model totally cannot be overlooked.

Measurement of Equivalent Pore Radius and Contact Angle Within Porous Media

The equivalent pore radius (i.e. capillary radius) and contact angle determine the capillary pressure generated in a porous medium. The most common method to determine these two parameters is through measurement of the capillary pressure generated by a test liquid and a reference liquid (i.e. a liquid with near-zero contact angle). The rate of rise technique commonly used to determine the capillary pressure results in significant uncertainties. In this study, we utilize our recently developed technique for independent measurement of the capillary pressure and permeability to determine the equivalent capillary radii and contact angle of water within micropillar wick structures. In this method, the experimentally measured dryout threshold of a wick structure at different wicking lengths is fit to Darcy’s law to extract the capillary pressure generated by the test liquid. The equivalent capillary radii of different wick geometries are determined by measuring the capillary pressures generated using n-hexane as the working fluid. It is found that the equivalent capillary radius is dependent on the diameter of pillars as well as the spacing between pillars. The equivalent capillary radii of micropillar wicks determined using the new method are found to be up to 7 times greater than the current geometry-based first order estimates. The contact angle subtended by water at the walls of the micropillars was determined by measuring the capillary pressure generated by water within the arrays and the measured capillary radii for the different geometries. This contact angle was determined to be 52.7°.