Abstract
This paper shows the results of the six pilot applications of a novel thermally activated particle system in mature water floods operated by Pan American Energy, at the San Jorge Basin (SJB), Argentina. These were injected between 2006 and 2008 and after up to three years of response, the evaluation is presented with notes on the well and reservoir character, treatment application and observed responses including incremental oil recovery. Field logistics, candidate selection, treatment design, operational aspects and pre and post application monitoring will also be described in detail.
SJB's water floods are characterized by low recovery efficiency due to an adverse mobility ratio as well as spatial reservoir rock anisotropy. This heterogeneity is typical of fluvial systems with high rock property contrasts inside the same channel body. A permeability contrast of 5 to 1 between the center and the edge of the channel is very typical. Therefore, injected water preferentially flows along the center of the channel, becomes a "thief zone", and breaks through to the producers prematurely, leaving behind unswept oil not contacted by the injection water.
In the last decade, many conformance trials failed to improve recovery efficiency. The main reasons for this failure were the utilization of an inappropriate chemical and / or ineffective placement of the application. However, since that time, this new particle technology has shown successful results by blocking thief zones deep in the reservoir. This blocking creates a new pressure gradient that promotes the diversion of injected water toward zones with high oil saturation. A confirmed success rate of around 80 percent seen in these pilots, with no apparent technical failures, has paved the way for a widespread deployment of the technology. In conclusion, the paper discusses treatment selection criteria for field scale application and feasibility for optimization.
