Hydraulics Influx Tracking (HIT) – Real-time monitoring gas expansion while circulating out an influx

Background More than 50% of the petroleum resources on the Norwegian continental shelf is still unused. Most simple wells are already drilled, and drilling is becoming increasingly complex. Developing technology for improved control of the downhole drilling process is, for that reason, one of the most important measures for improving recovery on the Norwegian continental shelf. The project will solve fundamental challenges related to monitoring for gas during difficult drilling operations to prevent potential kick scenarios from evolving unnoticed. In particular, the project will bridge critical gaps in existing technology that limits the safety of drilling formations with fractures and caves, such as in the Barents Sea, where losses of drilling fluid during operations can mask simultaneous gas flowing into the well. The project is about utilizing new sensor technology, mathematical models, and artificial intelligence to reconstruct a computer-based vision of what is going on in the well while drilling. Summary of project results The main outcome of Kelda's three-year "Hydraulics Influx Tracking" industrial research project is a new framework for monitoring the integrity of the mud barrier. This tool is based on new ground-breaking research in use of ensemble methods to estimate down-hole conditions after an influx has been taken. For example, the tool is able to provide real-time estimates of the probability of having gas in the system. A key result of this new research is the ability to distinguish if an influx is gas or liquid. Further, the tool is able to track the location and distribution of the gas during circulation. The method can also estimate the location of the gas influx and the most likely gas type. This is achieved by simulating thousands of scenarios in parallel and comparing the simulated results to online measurements. Based on these tracking capabilities, we are also able to predict in real time when gas will reach the surface. A further result of the HIT project is a new version of the Influx Management Envelope (IME) which is compatible with our planning and configuration tool LeidarPlan. This new IME facilitates contingency planning based on advanced hydraulics and PVT models. The new IME has been validated against external high-fidelity multiphase simulators. We have also developed a real-time version of IME, which allows contingency management in real-time, by monitoring influx severity. By incorporating online measurements and updated well data (geometry and fluid properties) from the rig, this new tool updates the IME in real-time. This tool has been incorporated in our commercially available Leidar RT package and has received much interest from our existing customers.

A new method for tracking a detected influx in the annulus has been developed during this project. The new algorithm can track an influx and follow it while it emerges along the wellbore to the surface. The concept can identify the gas type and distinguish gas from a non-compressible fluid (e.g. formation water). Furthermore, the influx's size and severity are determined, and information is aligned with the Influx Management Envelope (IME) in real-time. The system is still under development, and Kelda will continue to work on the concept and extension of its capabilities, i.e. to robustify the tracking algorithm and expand it to operate in conjunction with the Leidar pressure controller to circulate the gas out the surface safely.

More than 50% of the petroleum resources on the Norwegian continental shelf is still unused. Most simple wells are already drilled and drilling is becoming increasingly complex, either due to reduced drilling window in mature fields with depletion or injection for production support, or due to targeting reserves in more difficult reservoirs, such as high pressure, high temperature, extended reach, or karstified carbonate reservoirs. Developing improved technology for pressure control in drilling is therefore one of the most important measures for improved recovery on the Norwegian continental shelf. Currently, no technology exists that is capable of reliably monitoring the integrity of the mud barrier in case of gas expanding in the riser while drilling. This is a critical uncertainty when drilling in formations with losses, where a loss may mask gas displacing the mud column in the riser and compromising the integrity of the mud barrier. Tracking expansion of gas is key to distinguish gas expanding in annulus from simultaneous losses or influx while drilling, and is vital to be able to assess the integrity of the mud column. We will in this project solve fundamental challenges related to enable reliable real-time monitoring the integrity of the mud barrier in case of gas influx. This will result in new technology that will remove considerable uncertainty associated with the handling of well control incidents in drilling, which will be invaluable for HPHT (high pressure, high temperature) and deep water operations in order to prevent influx scenarios from escalating into severe incidents. In particular, the project will bridge the lack of technology for reliable monitoring gas migration when drilling in formations with losses, such as e.g. karstified carbonates.