System-in-the-Loop – Virtually Drilling 1,000,000 Feet at High Temperature
Authors: Hempel M. , Fabian C. , Heinisch D. , Hoehn O. 
Published: November 2024

Verification and validation of new high temperature Measurement-While-Drilling (MWD) and Logging-While-Drilling (LWD) technologies currently require extensive field testing, which is time consuming, can be costly, and can involve significant risk. In addition, critical corner cases such as extreme drilling conditions or safety critical scenarios like kicks can hardly be tested during field tests. However, field tests are important as standard high temperature laboratory testing can only take limited environmental and formation effects into account and thus does not cover the entire operational space of a newly developed system. To address these issues, this paper presents a novel system-in-the-loop approach to MWD and LWD testing that significantly increases confidence in system and service performance before the first commercial deployment.

The core of the approach is a system-in-the-loop setup, where multiple BHA components and software systems are connected in the lab, and the borehole environment as well as the formation environment is simulated. Each BHA component contains real electronics whereas the actuators and sensors which interact with the environment are replaced by corresponding real-time signal generators. The signal generators create and consume electrical signals as if they were real components. Digital and analog models are used to mimic real-world behavior of the environment. The environment models are either first-principle models or data driven models derived from in-situ (realistic) measurements of various operating conditions. For the system test, additional real hardware components, i.e. a surface data acquisition system and physical rig components like a hook-load sensor or a shaft encoder have been connected to the system under test.

The system-in-the-loop test has been successfully used for the verification and validation of a new high temperature drilling system. The new drilling system is composed of a rotary steerable system as well as multiple LWD and MWD tools. Different test cases, i.e., typical operational scenarios, have been modeled to validate the system behavior. Attention is paid to operation critical or safety critical scenarios such as extreme drilling dynamics. The test setup systematically runs the test cases to verify and validate the new technology continuously during development. During system testing, numerous environmental (e.g., temperature, pressure) and operational (e.g., string rotation, fluid flow rate) parameters are systematically altered. Running the scenarios as well as evaluating the results, is highly automated. This provides the ability to detect infrequent failure modes by drilling an equivalent of more than 1,000,000 feet under varying drilling conditions.

Specific subsets of the test cases were retested on a full-scale test rig and the results were found to be consistent with the laboratory test. Hence, it could be demonstrated that the time for field testing can be significantly reduced, operational risks can be minimized, and risks and costs associated with introducing new technologies can be notably reduced by using laboratory system integration testing continuously during system development. While existing approaches only cover parts of the system, the new approach allows the construction of more complex scenarios while covering a larger portion of the system and its operational space.