Enhanced oil recovery as well as environmental clean-up with steam injection is becoming an increasingly common method of extraction. There are several methods of steam flooding, two of which are Cyclic Steam Stimulation and Steam Flooding, with both being applied to oil reservoirs in California, Venezuela, the oil sands of northern Alberta, and environmental remediation sites like Visalia, California.
An advantage of steam injection includes reduction of the viscosity that ties DNPL (dense non-aqueous phase liquid), paraffins, and asphaltenes to the rock or soil surfaces. This frees the oil or DNPL so that it becomes mobile in the subsurface and then can be extracted.
Steam flooding for enhanced recovery relies on two mechanisms. The first is to decrease the viscosity and the second is a physical displacement of the oil by the steam resulting in a process that is similar to phenomena seen in water flooding.
Monitoring Steam Injections
Steam injection has many of the same issues as water and CO2 flooding: the areal extent of flooding, where fluid loss is occurring, as well as operators not having control over the fluid or knowing where the flood front is going. An additional precaution for steam injection is safety in the sense that the pressures and amount of steam injected can cause catastrophic explosive ground failure.
The Sub Rosa Monitoring approach will greatly reduce the uncertainties associated with fluid injections and provide long term advanced warning on the event of upward migration of steam. The ability of knowing where the steam and fluid fronts are on a daily basis will give the operator the ability to control the rate of movement and the areal extend of the affected zone. The daily monitoring will also reveal any areas where the steam fronts are moving vertically and how far they have traveled so the advancement can be stopped before any failures are realized.
The Sub Rosa Monitoring approach is to combine point source and volumetric sensors to provide a 3-dimensional image of the system behavior through time that provides enough information so the operators can optimize and control the injection process. This will allow a cost savings with the ability to recover more oil with less steam and provides the capability to stop injections in areas where the stream front is either moving in the wrong direction or approaching the surface causing unsafe conditions.