Jason D. Dykstra

Active Damping of Acoustic Ringing Effect for Oil Well Sonic Logging System

This paper presents a method to suppress the ringing effect for an acoustic transmitter used in oilfield wireline logging. The removal of ringing is desirable for acoustic logging as too much ringing can interfere with the processing of formation data. The existing approach uses a strong passive damper to damp out the vibration energy. This, however, limits the magnitude of the acoustic signal generated for logging purposes and can also create reliability challenges. This paper proposes a new method based on the active ringing damping in which a control signal is injected to compensate the transmitter motion vibration and is adapted under the change of operating environments. As compared to approaches developed for other acoustic applications, the method does not require the addition of extra sensors to the existing system and is designed to comply with the unique downhole logging hardware constraints. An iterative technique is used to adapt the ringing braking signal by learning the control patterns in the past cycles. Both simulation and experimental results are presented to demonstrate the effectiveness and robustness of the proposed method in the ringing braking.

Control of Rotary Steerable Toolface in Directional Drilling

This paper presents a detailed mathematical model of a rotary steerable drilling system (RSS) that adopts hydro-electromechanical devices to generate bending torque in adjusting the toolface (TF). Key requirements of RSS are to adjust the TF promptly to track the TF command, to maintain the TF in presence of the external disturbances, and to do so during the drilling process. Accordingly, a controller with a fast response time and effective disturbance rejection capability is desired for the RSS. The complexity and non-linearities of the RSS creates additional challenges to the controller design. This paper describes a simple and effective controller scheme that is designed based on the analysis of the system’s dynamics model. By decoupling the disturbances, physical state feedback, and non-linearities, the RSS can be controlled by using a simple and effective proportional-integral-derivative (PID) controller with the desired performance. The simulation results show that the proposed controller is effective against the disturbance and the variations of the parameters.Copyright

Indirect Adaptive Robust Controller Design for Drilling Rotary Motion Control

This paper presents the design and simulation of an indirect adaptive robust controller (IARC) for the rotatory drilling motion used in oil and gas exploration operations. To eliminate drill string vibrations, such as stick-slip, and achieve better control of drill bit rotating motion, an IARC controller was designed to compensate nonlinear friction torque directly and address system uncertainties during drilling. Simulation results are presented to illustrate the effectiveness of the designed IARC controller.Copyright

Acoustic ringing effect mitigation for oil well sonic logging

This paper presents a method to suppress the ringing effect for an acoustic transmitter used in oilfield wireline logging. The removal of ringing is desirable for acoustic logging as too much ringing can interfere with the processing of formation data. The existing approach uses a strong passive damper to damp out the vibration energy. This, however, limits the magnitude of the acoustic signal generated for logging purposes and can also create reliability challenges. This paper proposes a new method based on the active ringing damping in which a control signal is injected to compensate the transmitter motion vibration and is adapted under the change of operating environments. Both simulation and experimental results are presented to demonstrate the effectiveness and robustness of the proposed method in the ringing braking.

Uncertainty reduction of hydraulic fracturing process

Kalman filtering is often used to provide state estimates and corresponding estimation errors. Usually, the process noise and measurement noise information is assumed to be known and independent of inputs. However, for hydraulic fracturing processes that use microseismic monitoring technology, the covariance of measurement noise depends on the input signals, which provides a new method to reduce uncertainty of the system (i.e., estimation errors). The current work proposes two novel control methods for uncertainty reduction during hydraulic fracturing. One method is designed for cases where measurement data are available in real-time. The other method works under relatively long and time-varying feedback delays, whose sufficient condition for convergence is provided as well. Both newly proposed approaches are demonstrated on a simulated model of the hydraulic fracturing process with improved performance compared to industrial standard methods.

Vibrations of Curved and Twisted Beam

This paper studies the vibration of beams in 3D space with arbitrary shape. Based on results from differential geometry of curves, a set of beam vibration dynamics equations is developed, comprising six partial differential equations (PDE). The beam dynamics equations account for both the in-plane and out-of-plane beam vibrations simultaneously. In addition, the equations explicitly capture the coupling between different vibration mode types, which occur when the beam exhibits geometric irregularities such as bending, torsion, and twisting. The proposed beam dynamics equations are solved numerically. Comparison between experimental results and numerical results obtained by solving the PDEs proposed in this paper shows a good match for in-plane and out-of-plane curved beam vibrations.Copyright

Dynamic Modeling of Bottomhole Assembly

This paper presents a comprehensive 4D dynamic model of a bottomhole assembly (BHA) used for directional drilling of oil and gas wells. Although directional drilling has been in practice for some time, it still poses several challenges, particularly related to building an autonomous drilling system. The difficulty with drilling automation derives from the complexity of the process that includes interaction with the borehole and fluid (mud) flow and complex downhole vibrations, such as bit-bounce (axial), whirl (lateral), and stick/slip (torsional). Moreover, the measurements from a limited number of downhole sensors are usually contaminated with high noise levels, and can only be transmitted at low rates with long transmission delays using mud pulsing, or at a high cost using wired pipe. Therefore, it is preferable that the directional drilling system work autonomously with limited communication to the surface. To facilitate this, a compressive physics-based model of the BHA behavior was created to be used in control system development.In this work, the 4D dynamic model of the BHA accounts for the dynamics in rotation, axial motion, and bending along two lateral directions. The model uses a lumped mass-spring system and the system parameters (mass and stiffness) are derived from the shear beam theory of a flexible beam under certain boundary conditions.Simulation results of the model were successful in qualitatively replicating the three types of downhole vibrations, namely bit-bounce, whirl, and stick/slip, and are discussed in this paper. The model is shown to qualitatively replicate downhole conditions and can be implemented in real-time, thereby making it suitable for autonomous directional drilling control.Copyright