For one embodiment, a method is described that involves the instrumenting of an application of a computing system with at least one monitoring function, where the monitoring function is capable of operating in a run-time environment during processing of the instrumented application. The movement of data associated with the application is tracked by one or more monitoring functions. This data is at least partially identified by a storage location. Thereafter, a determination is made whether movement of the data from a first storage location to a second storage location is suspicious, and if so, suspicious movement of the data is reported.

Framework for efficient security coverage of mobile software applications using machine learning

Rotary-steerable drilling provides unique features such as an extended reach and accurate well trajectory control. These characteristics can notably increase drilling efficiency and safety. One of the main technical difficulties of rotary-steerable drilling is dynamically measuring the spatial attitude at the bottom of the rotating drillstring as the drillstring rotates. We developed a strap-down measurement system, with a triaxial accelerometer and triaxial magnetometers installed near the bit. The inclination and azimuth can be measured in real time even as the drillstring rotates. Although the magnetic system is the norm, we can use this system to achieve continuous measurement while drilling; to achieve this, a novel state-space model is proposed here and the Kalman filter is used to estimate the states. Simulation and experiments show that a continuous-survey system with a Kalman filter approach can improve measurement precision and reduce errors produced by drillstring vibration.

Continuous Real-Time Measurement of Drilling Trajectory With New State-Space Models of Kalman Filter

The measurement-while-drilling (MWD) system is mainly used to draw borehole trajectory in a coal mine. However, its measurement error directly demonstrates a deviation between the drawing locus and the actual path. Thus, it is imperative to effectively compensate the error in advance. In this study, the traditional-integrated error model is adopted and a low-cost calibration strategy, namely an incomplete calibration strategy, is proposed. In this strategy, the ellipsoid-fitting method is quoted to determine the combined bias and orthogonalize the coordinate frame of the triaxial accelerometer, and a new plane-fitting method is exploited to align the orthogonal accelerometer coordinate frame with the body coordinate frame of the MWD system; meanwhile, the theoretical basis is also stated with the simulation verification of MATLAB. Besides this, the scalar product constant method is finally employed to acquire the error model of the triaxial magnetometer on the condition of the previously calibrated accelerometer coordinate system. In the end, the newly designed calibration strategy was experimentally tested with the MWD prototype developed by ourselves. The results reveal that the strategy can not only be implemented without the help of other expensive auxiliary equipment but also has good performance in attitude reconstruction

A Low-Cost Calibration Strategy for Measurement-While-Drilling System

In drilling engineering, Toolface is an angle used to describe bit direction It is a challenging task to accurately estimate Toolface while drilling because of the downhole harsh conditions, but it is a primary step for the dynamic point-the-bit rotary steerable system (DPRSS) A new dynamic Toolface estimator is present, which fuses measurements from two accelerometers and one gyro A dual-accelerometer Toolface measuring method is designed to compensate the circumferential acceleration of DPRSS A nonlinear Complementary Filter (CF) is used to suppress the effect of vibration and axial acceleration The frequency-domain characteristics of nonlinear CF are analyzed and its natural frequency is determined adaptively based on real time drilling conditions This new estimator is validated on a DPRSS prototype under typical drilling modes; it is demonstrated with high robustness and follows the references satisfactorily

https://www.mdpi.com/1424-8220/18/9/2944/pdf

Dynamic Toolface Estimation for Rotary Steerable Drilling System.

This article is concerned with the estimation problem of Toolface for dynamic point-the-bit rotary steerable drilling tool systems. First, considering the unknown frequency and amplitude of vibration during the drilling process, the Toolface system is modeled as a time-varying stochastic system with unknown and time-varying noise covariance matrices. Under the assumption that the noises and their covariance matrices, respectively, obey the Gaussian distribution and the inverse Wishart distribution, the variational Bayesian-based moving horizon estimation algorithm is proposed. Then, the state and the noise covariance matrices are inferred by iteratively updating their approximate posterior probability distributions. Finally, simulations and experiments are provided to demonstrate the effectiveness and superiority of the developed estimation scheme. 

Variational Bayesian-Based Moving Horizon Estimation of Toolface for Rotary Steerable Drilling Tool Systems

In the oil drilling process, measurement-while-drilling system is usually used to provide real-time monitoring of the position and orientation of the bottom hole. Usually the bottom drill string attitude is measured on the condition that the drill string is static. Particularly, in rotary steerable drilling application, it is a challenging problem to accurately measure the spatial attitude (inclination, azimuth, and tool face) of the bottom drilling tool with the drill string rotating. A set of “strap-down” measurement system was developed in this paper, the triaxial accelerometer and triaxial fluxgate were installed near the bit, and real-time well deviation and azimuth can been measured. Laboratory experiments show that the dynamic solver methods will meet the project requirements. However, according to the drilling field tests, playback analysis on storage data of the underground measurement indicates that drill string vibration is the main reason for measurement errors. So, by setting a time window, the real-time measurement of the accelerometer and the flux gate signal are processed and analyzed, the movement patterns of the rotary drilling tool at the bottom were judged within the time window. Stick-slip phenomenon is utilized to improve the measurement accuracy and to reduce the impact of lateral vibration of the drilling string on the measurement system. We could take advantage of stick-slip phenomenon because of it cannot be avoided completely, although it should be avoided in order to improve the drilling string operating life. Simulation results showed that recommended dynamic survey approach could effectively enhance measurement precision, and deduce effect of vibration on resolve results.

Continuous Measurement-While-Drilling Utilizing Strap-Down Multi-Model Surveying System

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Continuous Measurement-While-Drilling Utilizing Strap-Down Multi-Model Surveying System