Application of Silicone Microemulsion

A novel method based on injection of silicone microemulsion was developed for restriction of water production in gas wells. The treating solution was a surfactant stabilized siloxane emulsion which was driven into the formation by water and nitrogen. According to the laboratory studies disproportional permeability modification is in the background of the water retention. The phenomena is attributed to inversion of microemulsion to macroemulsion initiated by spontaneous dilution by water and then entrapping of formed siloxane droplets by the pores. The method was tested at the largest Hungarian gas field (Algyö field, Hungary). Evaluation of the pilot test has definitely proved the beneficial effect of silicone injection on gas production and gas/water ratio: the gas production tripled and lasted for at least a half year. The encouraging results urged the operator to continue both the laboratory and the field tests with the aim at developing a method which might be used routinely in low permeable, tough gas fields and underground gas storage. Introduction Gas production from gas fields and underground gas storage is usually accompanied by substantial water production. The high water production and necessity of on-site water liquidation often deteriorate the recovery efficiency and hamper maintaining an environmentally friendly production. Therefore, substantial efforts had been made during the past years with the aim at developing suitable well treatment methods which may offer an effective, profitable and simple solution for high water production in gas fields and underground gas storage. However, on account of the inverse mobility ratio in gas/water system compared to oil/water case, viz. the flow of a fluid having the lower mobility must be restricted, the conventional and routinely applied water shut-off or profile correction methods (e.g. gels) can not be used for restriction of water production in gas wells. The only promising idea seems to be the utilization of disproportional permeability modification by polymer solutions and weak gels as proved by literature data and a few pilot tests1-8. Despite some encouraging field results published recently by Zaitoun at al.5,8 we may conclude that the basic problems has not been solved so far. On the other hand, a successful technique has great potential also in Hungary, and thus, a detailed laboratory research program followed by field experiments were launched a decade ago. Partial results were achieved by application of alcohol containing polymer solutions9, however, that method could be used only in medium or high permeable porous media. Since the gas is often produced from tough, low permeable formations and the polymers and gels being incompatible with such systems do not offer viable solutions for restriction of water production in gas wells, new concepts and chemicals must be searched in order to have any progress in this critical area.