Asphaltene deposition has been identified as one of the top flow assurance challenges in a number of onshore fields in Abu Dhabi with over 100 wells impacted. There was no device in the industry for direct measurement of asphaltene deposition, so the national oil company sponsored an R&D project to develop a sensor that could quantify the percentage of asphaltene in the flowing oil.
Current ways of identifying an asphaltene problem rely upon accessibility checks with slickline units and hence clean-up operations are reactive and are often too late. In order to detect the problem earlier, an asphaltene specific real-time sensor would be required. The sensor design selected built on the concept of Electron Paramagnetic Resonance (EPR), wherein free-radicals in the asphaltene are resonated by an external magnetic field. The EPR signal is directly proportional to the amount of asphaltene in the crude, with a signal drop indicating potential deposition upstream of the sensor.
By focusing on the asphaltene free-radical response, rather than looking for a broad range of molecules, it proved possible to miniaturize and ruggedize a device for oilfield applications. It remained important to prove that this modification did not casuse a loss of resolution. For the first field trial in these onshore fields, instead of having the device installed directly into one well, the system was tested off-line so that daily analysis from 15 different wells could be achieved and device resolution could be tested. The resolution proved to be better than 0.1%. Moreover, some wells showed nearly 5% variation from one day to the next while other wells showed barely 1% variation. The wells with the higher standard deviation were those which had historically seen more asphaltene problems. Results from these 15 wells exceeded expectations, so a decision was taken to launch a second field trial with the device now able to be mounted inline at the wellhead for real-time continuous monitoring. It is anticipated that the application of this system will help plan clean-up jobs before a well gets totally plugged. This should lead to substantial cost savings in addition to minimizing well downtime and loss of production.
This paper presents a novel solution that was developed from inception or "ideation" all the way to commercialization through a research collaboration between a national oil company, a university and a start-up technology provider. The outcome is an industrial Internet of Things (IoT) real-time monitoring device, the first of its kind, that detects asphaltene deposition and makes it possible to optimize chemical programs by incorporating surface data into an integrated flow assurance management system.