APIT is a computational software based system which performs real-time test analysis, reporting and automated result interpretation of FITs/LOTs/XLOTs based on surface and downhole data. This paper presents the challenges for the current pressure integrity testing and introduced a new solution called automated pressure testing (APIT) system. This has included system framework and integration to cementing units, models and algorithms to determine system compliance and fluid leakage, fracture closure pressure, calibration techniques and validated results. Based on a minimum of preconfigured user input, the APIT system covers all test phases, from pressurization, fracture propagation to shut-in and flowback. The system identifies unexpected test behavior and triggers warnings by continuously evaluating key test metrics such as leakage rate, system compliance and surface pressure during each test phase. This APIT system was tested optimized and validated using various historical field data in order to provide Proof-of-Concept of algorithms, test sequences and graphics user interface (GUI). Both successful and unsuccessful data chosen from NCS and the international arena were tested. The automatic interpretation algorithms from APIT are aligned with manual test interpretation performed internally in Statoil. The APIT system is believed to be a safer and more efficient pressure testing alternative to the current manual counterpart.
Achieving optimal performance during drilling of complex well trajectories is often hindered by downhole drill-string vibrations and stick-slip. These can lead to drill bit and downhole tool damage, drill-string wear possibly leading to a twist-off, or formation damage. Recent advancements in drill-string vibration interpretation show that the sources of excitation are not only at the bit but anywhere along the string. Therefore, a solution that uses distributed along-string damping elements based on magnetic damping is investigated. This paper presents the design principles of a laboratory-scale setup to verify the concept and the accompanying test results. Previously published numerical results show that stick-slip can be attenuated using the distributed damping elements. The elements attempt to reduce drill-string vibration by attenuating the sources of negative damping, and by increasing the sources of positive damping. Mechanical friction between the drill-string and the borehole, a major source of axial and torsional vibrations, is reduced, and its axial and tangential components are decoupled. Magnetic viscous damping is introduced by utilizing eddy current braking at the level of each element. A laboratory-scale setup consisting of a 10-meter-long horizontal apparatus has been constructed to verify the damping effectiveness of an individual element. The setup was designed to mimic downhole drilling conditions such as drill-string elasticity, friction forces and inertial moments, and to recreate real-world adverse conditions such as vibrations, stick-slip, and twist-off. Sensors and actuators positioned along the experimental setup allow control of the rotational and axial velocities, contact forces at various locations, and adjustment of the magnetic braking force. Stick-slip was introduced in the system through an adjustable side force imposed on the drill-string as well as through a stepper motor operating in torque mode simulating the bit-rock interaction. The first series of experiments in the laboratory-scale setup were aimed at evaluating the braking force obtained in different operating conditions. By controlling the strength of the eddy current effect, the magnitude of the braking force could be varied, and thus, the damping effectiveness of the element could be estimated. The braking force, measured by a load cell, was found to increase linearly with the rotational speed and with the strength of the magnetic field. The second round of experiments were focused on demonstrating how the magnetic braking effect helps damping out torsional vibrations and mitigating stick-slip. A novel concept for damping stick-slip vibrations using magnetic damping elements distributed along the drill-string has been implemented and demonstrated at laboratory-scale. This concept aims to mitigate stick-slip vibration by addressing its root cause, the friction forces along the drill-string. The experimental setup can also be used to prototype and test new control strategies for damping of drill-string vibrations.
The transition towards drilling automation in the oil and gas industry has increased the need for digital infrastructures for development and testing of new technology. This includes infrastructures to facilitate changes in work processes and technical competences. This paper describes the design and use of OpenLab Drilling, a digital infrastructure with applications in education, technology development and testing. OpenLab Drilling offers access to a high fidelity drilling process simulator capable of simulating transient hydraulics, temperature, torque and drag, and cuttings transport. Since 2018, the infrastructure has been publicly available for students, researchers and engineers who need realistic drilling data for technology development, demonstration and education. The simulated drilling data can be accessed by several means. First, through a user-friendly web application used as a tool for teaching the physics involved in drilling operations. Secondly, drilling data can be accessed programmatically through a web API or via programming language APIs written in MATLAB, Python and .NET. Thirdly, OpenLab offers a fast communication interface that can be used for applications that are closer to hardware, and which require a realistic Hardware in The Loop (HIL) infrastructure. This paper describes the objectives of OpenLab as a project, its system architecture, its simulation capabilities, the design of its web application, and its various communication interfaces. The paper also presents projects that uses OpenLab in education, research on machine learning, semantical representation of drilling data, and other industrial relevant activities. The paper is naturally divided in two parts: The design of the infrastructure, and its applications.
After drilling out cement at the start of a new wellbore section, a formation integrity test is routinely performed to verify the integrity of the new formation and the cement at the casing shoe. Test results can have large impacts on the drilling operation, such as motivating remedial cementing operations, changing the drilling fluid mass density or the setting depth of casing strings. Interpretation of the test results are often made difficult for a number of reasons, including significant fluid losses to permeable formations, large friction pressure losses, compression of trapped air and unstable pump operation. This paper presents a new supervisory system providing real-time test analysis and automated result interpretation of pressure integrity tests, leak-off tests and extended leak-off tests. Based on a minimum of preconfigured user input, the system covers all test phases, from pressurization, fracture propagation to shut-in and flowback. Rather than relying on computationally intensive modelling of downhole physics, regression techniques are applied to relate surface pressure to injected fluid volume, shut-in duration and volume or time in flowback. System compliance and fluid leakage rates are determined prior to leak-off using a nonlinear regression model. The calibrated model is in turn used to generate prediction intervals for detecting leak-off and fracture pressures. Extended leak-off interpretation is based on the system stiffness approach, in which fracture closure is associated with a reduction in system compliance. We apply regression techniques to search for fracture closure during shut-in and during flowback. The system identifies unexpected test behavior and triggers warnings by continuously evaluating key test metrics such as leakage rate, system compliance and surface pressure during each test phase. The development is based on few model assumptions. Low-pass filtering combined with regression techniques ensure that the system is capable of analyzing field tests of variable quality and with noisy surface sensor measurements. We assess the performance based on historical tests that are representative of the variation in possible pressure-volume behaviors and with typical noise levels on input sensor signals. The system output corresponds well with the original manual test interpretations, and provides in most cases reliable determination of leak-off and fracture pressures, fracture propagation and fracture closure pressures. Real-time test supervisory functionality in addition to standardization of test interpretation and data storage are immediate benefits of system implementation.
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