Clamp-on Mud Flow Rate and Quality Measurement

After the fatal 2010 Macondo drilling accident in the Gulf of Mexico, US authority report concluded on the need of real-time drilling fluid (mud) control, to avoid similar situations. Missing drilling fluid (mud) control accounts for a significant loss in drilling production time. Consequently, drilling efficiency and safety is a priority for NCS and high North drilling activities. As existing mud flow rate and mud quality measurement solutions are expensive and not technically suitable, the industry searches alternative solutions. Equinor approached Xsens AS in 2018 for mud flow testing of the Xsens clamp-on ultrasonic flow meter for mud flow measurement. Xsens technology confirmed promising performance, on real drilling fluids, for flow rate measurement and capability of detecting sudden variations in mud flow rate, known as kicks, identifying changes in reservoir formation, during drilling. The IPN project aim to further develop the Xsens technology for robust mud measurement of in-flow as well as return flow conditions, which include reservoir fluids and rock particles in different sizes, hence a complex fluid. The IPN R&D scope combines advanced Xsens multi-path acoustic flow measurement with technology front of drilling fluid dynamics, both technology areas covered by project R&D partner NORCE Reserach Institute core competence. Mud rheology versus acoustic measurement wil be examined. For the challenges of measurement disturbances from particles and variation in drilling fluid properties machine learning is a focus area. After successful testing of a prototype meter on various mud qualities at BakerHughes' facility for drilling fluids at Mongstad outside Bergen in 2021, two Xsens mud meters were installed offshore on the drilling platform Askepott for Equinor, for in-flow measurement of mud. Offshore tests in spring 2022 confirmed robust acoustic flow measurement in drilling fluids, for Xsen's multi-path ultrasonic flow meter. Xsen's flow meters installed on Askepott are upgraded for permanent operation on the platform and TRL7 approval from Equinor for in-flow measurement of mud, after agreed operating hours. Approved clamp-on flow meter for in-flow of mud opens up a significant market for Xsens AS. In parallel with testing offshore in 2022, the Xsens mud flow meters have been tested for return flow of mud. Measurement of mud with added particles corresponding to drilling cuttings (cuttings) has given good results. The project has also included studies for measuring mud in partially filled pipes, which are planned to be continued in a new project with several of the industrial partners. Both NORCE and Høgskolen på Vestlandet (HVL) have contributed to models and algorithms for acoustic measurement in mud. Machine learning has been used as a method for improved measurement robustness in drilling fluids. Two master's studies in acoustics at the University of Bergen, Department of Physics & Technology have been associated with the project, in the field of qualitative measurement of liquids using sound speed measurement.

The mud flow meter development has the potential of implementation in offshore/onshore drilling facilities world-wide. A clamp-on in-flow mud flow meter is developed and some work still remain for a commercial return flow mud meter to be launched. When launched the system is an enabler for emerging drilling methods, aiming at enhanced drilling efficiency e.g. MPD); as much as 30% loss of production time results from poor drilling reliabilityXsens AS estimate return of invested 9 MNOK project cost after 3-5 years and a 100-200 MNOK net profit after 5-6 years. The technology developed is applicable to a lot of other applications including water/waste water processing and infrastructure.

Missing real-time information on drilling mud behavior accounts for a significant part of 30% loss of offshore drilling production time resulting from poor drilling reliability. Drilling efficiency and safety is a priority area in the OG21 strategy for NCS and high North drilling activities. Equinor approached Xsens AS 2018 for testing of clamp-on ultrasonic flow meters installed directly on the mud pipe and test results (SPE-195624-MS) confirms the potential to cover required mud qualities and fluid complexity. The planned innovation project target in- and return-flow of both water- and oil-based mud flow rate measurement. Information on mud density and viscosity will also be addressed, as well as partly filled pipe flow measurement. The project R&D team covers acoustics, mud rheology, machine learning and industry expertise. Research is required to obtain a model for the velocity profile calculation of non-Newtonian drilling fluids, valid for fluid information obtained by multi-path acoustic guided wave sensors, forming chordal paths within the pipe cross-section, at a known distance between pipe center and pipe wall. The model must account for variation in mud rheology of different mud qualities including presence of cuttings and gas. In addition to flow measurement correction, the model will be used for calculation and correction of mud density and viscosity measurement. The most critical research challenge is to obtain the accuracy required for the complex fluid behavior and variation in fluid qualities of mud, hence multi-path and multi-mode measurement enhanced by machine learning will be implemented for continuous measurement improvement. The project includes prototype testing at North Sea offshore drilling facilities towards end of the project. For Xsens the planned clamp-on mud flow meter represents an attractive business case at high ROI for oil companies and drilling operators, for commercialization immediately after project completion.