Digitizing Chemical Data for Real Time Flow Assurance

By minitiaturzing and ruggedizing laboratory equipment historically used for geochemical applications, it is now possible to digitize chemical attributes of molecules as they flow through the wellhead. Specifically, the number of unpaired electrons in outer-orbitals can be tracked in real-time as well as the hyperfine interaction of those electrons with spin-properties of nuclei within their associated molecules. This sounds very esoteric but in fact has a direct relationship with traditional flow assurance problems that have previously been very difficult to manage. For example, considering those electrons which correspond to free radicals within asphaltene molecules, then, in the presence of a very strong magnetic field, they will resonate at a specific microwave frequency. By exposing the well fluid to exactly that combination of magnetic and RF fields, the amplitude of the resonance is proportional to the number of asphaltene molecules. Unlike some optical and infra-red techniques, this gives a measurement of the total amount of asphaltene flowing, not just a measurement of the non-dissolved component. This measurement can be made continuously, so that gives a time-series analysis of the percentage of asphaltene that is flowing in the oil. AI-based software has also been written to extract further information from the resonance data, such as the water-cut and gas-oil ratio. Operators can use this combined information to optimize their flow-assurance strategies, for example, to give immediate feedback on the result of changing an inhibitor or dispersant. An initial version of the tool was deployed for a field-test in Abu Dhabi in Q4, 2017. Data from the system was transmitted via the cloud to asphaltene experts remotely monitoring the data. The resolution of the device proved better than expected, which allowed the system to give a previously unseen dynamic view of asphaltene chemistry. One surprise was that the asphaltene percentage might vary significantly over the course of a few hours, even when the surface pressure and flow-rates stayed the same. Troublesome wells had the highest standard deviation which gives a new key performance indicator (KPI) for flow assurance risk. Another unexpected result was that surface asphaltene levels would drop for a few days after a xylene soak, before slowly returning back to their baseline. This indicates that a freshly-cleaned tubular is more attractive for asphaltene deposition, and stays that way until a sufficiently thick asphaltene coating has accumulated. Based on these results, additional hardware has been delivered to Abu Dhabi to begin a long-term pilot study on the use of electron resonance data for asphaltene management. Moreover, the device opens up to the oilfield traditional laboratory uses of electron resonance such as identification of kerogen maturity and geochemical rock typing.