Traceability of materials and components has always been important to DNV’s work to safeguard life, property and the environment. Bio-technology has revolutionised this, and the latest developments in DNA technology have opened a gateway for a new line of services for DNV’s partner company ChemTAG.
The Norwegian government recently awarded 1.85 million NOK to ChemTAG as part of its DEMO 2000 programme, aimed at increasing oil industry competitiveness. The focus of ChemTAGs project, which has a total budget of 6.7 million NOK, is on improved oil reservoir management using environment-friendly, DNA-based tracers. The scope is to design, develop and qualify these tracers for use in reservoirs. Using tracers in a reservoir can provide information about its properties that is vital to optimum reservoir management. Small amounts of tracers are introduced into the reservoir through the water and gas injection wells. When the tracers are later identified in the production wells, they provide information about flow patterns in the reservoir. Combined with geological data and simulation models, a better understanding of the oil reservoir can then be obtained. Tracers have been successfully used in many oil fields worldwide.
Support from the oil industry
The research, performed jointly by ChemTAG and DNV, has strong support from the oil industry. Operators realise that the use of tracers will grow in importance in enhancing oil recovery, and are searching for new cost-efficient and environment-friendly tracer molecules. If the testing of DNA tracers in reservoirs is successful, this will give enormous added value to the oil industry, says Odd Tonby, managing director of ChemTAG.
Tracers must have chemical, thermal, biological and mechanical robustness, follow the reservoir flows intimately, and be detectable in extremely small concentrations from the produced fluids, even after several years of retention time under reservoir conditions. The applicability of DNA-based tracers against such criteria is the key question that the oil industry wants the DEMO 2000 project to answer, says project responsible Ståle Selmer-Olsen.
Motivated by environmental treaty
In complex reservoirs, the relatively small number of currently available tracers limits the amount of information obtainable from tracer injection. Furthermore, the Norwegian Pollution Control Agency has urged the oil companies to develop new tracers with low environmental impact. This is motivated by, and in compliance with, the environmental treaty PARCOM, which Norway has signed, states Ståle Selmer-Olsen.
DNA technology has a great potential in providing new tracers, says Odd Tonby. The technology has found application in several recent problems of water leakage, groundwater reservoir and pollution contamination. DNA tracers have successfully traced water movements through crevices in rock. The tracers have previously not been tested under oil-reservoir conditions and could become an alternative or a complement to conventional tracers, which often are radioactive or have global warming potential. Explains project manager Håvard Thevik, In principle DNA tracers can be provided in unlimited numbers which do not need to be qualified for field use individually, a costly limitation for convent-ional tracers.
Adds Pål Bergan, DNVs member of ChemTAGs board of directors, This is an exciting technology with a great commercial potential - not only in reservoir management, but for a wide range of industrial applications. Examples include tracing of pollution, identification of food and property, and proof of origin and authenticity. One might call it forensic examination in liquid form.
No toxicity, no contamination
ChemTAGs patents utilise the four main components of the DNA molecule for alphanumeric coding. By choosing the sequence of the components, a code in words or numbers can be stored in the DNA molecules. These molecular tags can be produced in large numbers using standard laboratory equipment. Only a laboratory in possession of the right key can decode the information coded into the DNA molecule. ChemTAG has identified several possible methods for adding DNA to any liquid substance: attached to solid particles, incorporated in pollen or spore particles, or as free (naked) molecules. Free DNA molecules have been most extensively tested, but all methods are under consideration.
The DNA used is synthetically produced in laboratories, which means that it carries no genetic information that can interact with living organisms, and is completely harmless. DNA tracers are detectable at extremely low concentrations, and do not affect the properties of the reservoir fluids nor pollute the environment. Says Håvard Thevik, When analysing a sample in search of DNA molecules, there is no need to find the needle in the haystack. In a so-called polymerase chain reaction, a DNA molecule can be duplicated a billion times. This makes it easy to extract DNA molecules for further analysis, which in turn makes it possible to trace the displacement of large amounts of water and oil with a small number of DNA molecules. Typically, one mg of DNA is detectable even when mixed with 1 million cubic metres of water.