Studies of the pore space of the UPM-K, UAM-50, UAM-100 composite ultrafiltration membrane

The development of methods for assessing the distribution of pores by radii (or diameters) and studying the microstructure of the surface of a membrane partition is an urgent task. The authors of the paper carried out experimental studies of the pore diameter distribution for the UPM-K ultrafiltration membrane, determined the porosity and hydrodynamic permeability of the UAM-50, UAM-100 membranes. The analysis of the experimental results showed that the UPM-K ultrafiltration membrane had an average pore diameter of 54 nm. The UAM-50 and UAM-100 membranes were characterized by an asymmetric structure (an active layer (dense) and a porous substrate), while the pores were 2.5–40 and 10–40 nm in size, respectively. The experiments on the study of the hydrodynamic permeability of UAM-50, UAM-100 ultrafiltration membranes when separating a solution of sodium lauryl sulfate showed that the kinetic response curves of the “membrane-solution” system were conventionally divided into two stages. The first stage of the process was faster and lasted only a few minutes. After 7.8 and 13.05 min, the hydrodynamic permeability decreased by ~ 27 %, 7 %, which was due to structural changes in the cellulose acetate layer under the action of mechanical load (transmembrane pressure). The second stage was slower – with a duration of ~ 33 and 60 min and a decrease in hydrodynamic permeability by 41 % and 11 %. Based on the analysis of the approximating function, the rate constants of the membrane separation of solutions and the empirical coefficients of the equation are found.

Numerical modeling of wave processes in fractured porous fluid-saturated media

Одной из актуальных задач современной прикладной геофизики является выделение характерных признаков наличия развитой трещиноватости в пласте по сейсмическим данным. Более того, необходимо выделять флюидозаполненные системы трещин, образующих связанную систему трещин, способную обеспечивать достаточную гидродинамическую проницаемость резервуара. В настоящей статье представлен численный алгоритм расчета волновых полей в трещиноватых пороупругих средах, основанный на конечно-разностной аппроксимации уравнений Био. На основе численных экспериментов показано, что связность трещин, т.е. наличие систем пересекающихся трещин, существенно повышает поглощение сейсмической энергии, что обусловлено возникновением локальных потоков флюида внутри трещин. Приводится детальный частотный анализ затухания сейсмических волн и обусловленной этим дисперсии. One of important problems in modern applied geophysics is to distinguish the specific indications of developed fractures in geological formations using seismic data. In addition, it is necessary to distinguish the fluid-saturated systems of cracks capable of providing a sufficient hydrodynamic permeability of reservoirs. In this paper we propose a numerical algorithm to study wave fields in fractured porous fluid-saturated media on the basis of a finite-difference approximation of Biot's equations. Our numerical results show that the intersecting fractures significantly increase the absorption of seismic energy due to the appearance of fluid flows in cracks. A detailed frequency analysis of seismic wave attenuation is given.