Tracer technology is very popular in petroleum engineering applications. This includes applications in reservoir characterization, reservoir modeling, improved oil recovery, etc. Most of the current tracer technology uses radioactive isotopes that are not environmentally friendly and require strict safety precautions. We propose the use of rare long-lived and stable noble gas isotopes as tracers where instead of the decay of the radioactive material, we will use optical detection.
Due to their chemical inertness, rare noble gases offer the advantage that they do not react with the environment with which they are in contact. Our research employs for the first time optical detection by collinear fast beam laser spectroscopy. It has the advantage that the noble tracer projects based on multiple tracers can be designed in the future.
In this work also the optical hyperfine structure of long lived was used to identify the tracer atoms. The technique has been successfully applied to stable krypton isotopes. The selectivity is at the one part in 1010 level and the sensitivity is at a few hundred ions. This method is several orders of magnitude more sensitive than the standard nuclear decay detection. This new tracer technology offers a safer and more accurate option for applications in the oil and gas industry. This research work is currently being done in Qatar for application in the Qatar's North Field.
Tracer technology has very important applications in the oil and gas industry. Chemical or radioactive tracers are used to label fluids from specific locations in the reservoir, and trace it as it appears at other locations (Huseby et al., 2008). The results are used to evaluate inter-well connectivity and reservoir continuity, detect high permeability zones, (Anisimov et al., 2009), identify residual oil saturation during waterflooding or miscible gas flooding applications (Devegowda et. al., 2009; Cockin et al., 2000), assess the success of fracture treatments (McDaniel et al., 2009) and many other applications such as precipitation in near-wellbore region and reservoir fluid sampling (Stamatakis et al, 2006; Gozalpour et al., 2005).
The application of tracers in the petroleum industry has been around for decades (Gore and Terry, 1956; Watkins and Mardock, 1954), and has proven to yield more accurate results on reservoir characterization than the use of pressure and rate data (Datta-Gupta et al., 1997; Huseby et al., 2009). Radioactive tracers such as Radon or natural tracers such as the ioncontent of water are used to track injected fluids and identify the path it traverses. However, in most of the applications, the results yield qualitative evaluations rather than quantitative information about the reservoir.
The new tracer technology we're proposing for application in oil and gas reservoirs has the advantage of a very high selectivity and sensitivity over traditional tracer technologies. The use of optical detection rather than radioactive decay or mass spectroscopy results in the ability of detecting one particle in 1010 particles. This is achieved using collinear fast ion beam detection. Nobel gases are the best candidate for such application. In the next section, we review the technology of optical detection, discuss the experimental setup and procedure for our work, and present some of the problems in the petroleum industry that can be addressed by applying this technology.