The use of foamed gels as blocking agents is an alternative method to reduce excessive gas or water inflow during oil production. Field trials have demonstrated that foamed gel is a very cost effective technology. However, the mechanisms of foam gel flow and blockage in porous media are not yet well recognized. In this work, a pore level approach has been taken to investigate the complex flow of foamed gels in porous media, through visual observations in transparent etched-glass micromodels. This paper presents experimental observations on foamed gel propagation in heterogeneous pore models. This work also evaluates the effect of foamed gel on gas and water mobility, the mechanisms of gas and liquid flow through a foamed gel network previously placed in the porous media, the effect of pore structure and foam texture on blockage effectiveness. The experimental observations reveal that foamed gels provide a higher flow restriction capability than conventional aqueous foams. Direct observations of foamed gel propagation at the pore level indicated that foamed bubbles are broken and reshaped within the porous media. Foamed gel blockage effectiveness increases with porous media permeability and conductivity. Finally, experimental results demonstrated that foam texture has an unquestionable influence on foamed gel blockage effectiveness.
Foam is applied broadly as a mobility-control and profile modification agent for flow in porous media. Foam is a dispersion of a relatively large volume of gas in a small volume of a liquid. It is generated inside a porous medium when a liquid containing a foaming agent is mixed with either an externally injected or an in situgas (1), with the gas occupying typically 50% to 99% of the total volume. There is relatively little work in the literature regarding foamed-gels (2)–(9).
In a previous paper (10) experimental work was performed in order to delineate the effects of foamed gel texture on trapping mechanisms and the resulting distribution and magnitude of trapped bubbles. Displacement tests on a 2D network micromodel were carried out to visualize at pore-level scale the trapping mechanisms of foamed gel in porous media. Additionally, a new X ray-Microtomography technique was used to evaluate the internal microstructure of foamed gel through layer-by-layer visualization of bulk foams (10).
In the present study the propagation of foamed gel in heterogeneous etched-glass micromodels is reported, along with its effect on gas and water mobility. The specific objectives of the study were as follows:
Evaluation of the propagation of foamed gel in heterogeneous pore models through direct observation.
Determination of the mechanisms of gas and liquid flow through a foamed gel network previously placed in the porous media.
Study of the effect of porous media permeability and conductivity on foamed gel plugging.
Estimation of the influence of foam texture on foamed gel blockage capability.
Determination of the foamed gel gas blockage effectiveness versus aqueous foam gas blockage capability.
Apparatus. Fig. 1 shows a schematic of the foam flow experimental set up (10).