Foam Injection Test in the Siggins Field, Illinois

Abstract

A pilot test in this tired, old field, confirmed the laboratory-derived conclusion that foam can do more than soften a beard or ruin a river. It can decrease the mobility of gas and water, stop severe gas channeling, and decrease produced WOR's. Introduction A new method to increase oil recovery has been studied in the laboratory. In this method, foam is used to improve the displacement of oil from porous media by drive fluids such as gas and water. In studies of various aspects of foam-flooding, many interesting, novel, and useful properties of foam have been revealed. The first work on foam-flooding dealt with its use in oil recovery. It was found that foam was better than gas as an agent for this purpose - it increased displacement efficiency. The initial work with foam also indicated that it could improve the conformance of gas-drive oil recovery processes because it selectively reduced the gas permeability of reservoir rock. Further studies showed that foam-flooding recovered more oil from a linear stratified sand system than a conventional waterflood. Because of the simultaneous improvement in conformance and displacement efficiency, foam-flooding was looked upon as an improved oil recovery process, with gas and foaming solution injection being used as an alternative for waterflooding. Investigations of the mechanism of gas and liquid flow through porous media in the presence of foam have indicated that foam will not move through the media as a body. Instead, the liquid and gas forming the foam separate as the foam films break and then reform in the porous system. When enough foam is Present, the flow of gas through the foam stops and Present, the flow of gas through the foam stops and the flow of liquid is greatly reduced. On the basis of these results, we would not expect it to be practical to drive foam through a reservoir. Rather, foam can be expected to improve the sweep of fluid injection processes in heterogeneous reservoirs by reducing or processes in heterogeneous reservoirs by reducing or blocking flow in more permeable zones. The plugging characteristics of foam have several possible uses:to reduce gas coning,to stop possible uses:to reduce gas coning,to stop leaks in gas storage reservoirs, andto reduce flow of fluids through high-permeability channels in oil reservoirs. Our work on the use of foam to selectively plug a high-permeability channel has shown that the plugging action is greatest if gas instead of water is injected plugging action is greatest if gas instead of water is injected after the foam. In laboratory experiments, the mobility of gas has been drastically reduced by foam for periods up to 2 months. The permeability of a porous system to water following a foam bank has been reduced in many cases to between 10 and 50 percent of its initial value. However, water following a foam bank tends to dilute the foamer solution and wash it away. Also, it becomes more difficult to maintain the plugging action of foam as the permeability of the channel increases. Foam will have the least favorable environment when it is used to plug a continuous fracture to stop the flow of water. We tested more than 100 surfactants for use in foam-flooding. Our work showed that certain ethoxylated alkyl sulfates containing amide stabilizers were efficient foaming agents for our purposes. JPT P. 1499