Biopolymer plugging effect: laboratory-pressurized pumping flow studies

The use of biopolymers and their producing microorganisms to form a wide range of impervious barriers, as well as for enhancement of oil recovery (EOR) is already well documented. Both of these important applications of biopolymers are based on their plugging characteristics. Flow systems are essential to examine the plugging effect of biopolymers under different conditions, in order to select suitable biopolymers for a particular application. In the present study, the plugging effect of a number of biopolymers, namely xanthan, polyhydroxybutyrate (PHB), guar gum, polyglutamic acid (PGA) and chitosan, has been investigated in a laboratory-pressurized pumping flow system. The present work is also targeted to study the correlation, if any, between biopolymer structure and plugging effect. The experimental system included a horizontally mounted sand-pack column and provided a constant flow, using a transducer and recording the pressure difference. Thus, the permeability ratio could be evaluated for each biopolymer as models in the field. All of the biopolymers studied have shown positive plugging effects by reducing the permeability of sand over the 11-day experimental period. The best plugging effect was obtained for PHB, which can reach more than a billion-fold permeability reduction, followed by chitosan and PGA, with a million-fold reduction of permeability. These biopolymers can be successfully used alone or in combination in field applications for stabilizing underground contamination to stop the plumes of subsurface pollutants, as well as for improving oil recovery from the field. Our results show that the plugging effect is influenced by the structure of biopolymers. This study will lead to a new method for characterizing the biopolymers used for plugging.