Water production due to coning is a long standing problem in the oil industry. Based on Muscat's model it is easy to recognize that a horizontal barrier at the hydrocarbon/water interface could be used to block off water. The problem is in its placement. Attempts have been made to use cement, and failed. The failure is due to the difficulty in creating a horizontal fracture. Other high viscosity fluids have been tried, and they failed similarly.
Polymer gels that have a low viscosity at the time of mixing and that can form a gel after some time delay have been applied quite successfully in blocking water channels in flooding projects. If these polymers were used to create a horizontal barrier there can be problems in dilution or slumping. For those polymers that have an initial viscosity close to that of water mixing with the 100 % saturated water formation could cause enough dilution so that gelatin fails. While this is less likely to happen to those polymers that have a higher initial viscosity, their high density could effect slumping to the bottom of the water formation. Gelatin there cannot stop water coning.
A solution to these problems might be achieved by emulsifying these polymers in oil. We have performed laboratory experiments to show that it was possible to make such an emulsion, and that the emulsified polymer was still able to from a gel. The density difference in oil, emulsion, and water allowed the emulsion to be placed right in between oil and water. The emulsified gel was competent enough to hold a column of water inside a test tube. Our objective is to place an emulsified polymer gel on top of the aquifer, so that it can from an effective barrier to block off water production.
The production of water from aquifer underlying hydrocarbon reservoirs is a long standing problem in the oil field. Muscat1 showed that de-pressurization at the producer causes the bottom water to rise in the shape of a cone with its apex right below the well. Once it reaches the perforations, production of water begins. The ratio of water to hydrocarbon production would also increase rapidly. If water disposal cost becomes too high, then the well has to be shut-in. This is commonly known as water coning.
horizontal barrier on top of the cone. In the 50's and 60's a number of, viscous fluids2,3, including cement4, had been proposed to perform this task. None of these blocking agents are being used now, because it is difficult to inject a large enough volume of these fluids to form a significant sized barrier.
In recent years a number of polymer gels5–17 have been applied successfully in treating water channeling in flooding projects, and communication behind casing. They all have relatively low viscosity at the time of mixing and they either become much more viscous, or form a gel over time. The low initial viscosity allows them to be placed deep into the reservoir, and the high viscosity or gelatin later allows them to block off water channels.
