State Dependent Delayed Drill-string Vibration : Theory, Experiments and New Model

L.J. Pei would like to acknowledge NNSF of China (No. 11372282) and China Scholarship Council.Peer reviewedPublisher PD

3D and 4D Seismic Technics Today

Years ago, exploration was done through surface observations and divining rods now, it is done by satellites, microprocessors, remote sensing, and supercomputers. In the 1970´ s, the exploration success rate was 14 percent, today, it is nearly 29 percent. Not so long ago, three dimension (3D) seismic diagnostic techniques helped recover 25-50 percent of the oil in place now, 4D seismic helps recover up to 70 percent of the oil in place. 3D and 4D seismic and earth imaging systems also help in understanding the subsurface flow of other fluids, such as groundwater and pollutants.Seismic surveys a technique in which sound waves are bounced off underground rock struktures to reveal possible oil and gas bearing formation are now standard fare for the modern petroleum industry. But todays seismic methods are best at locating structural traps where faults or folds in the underground rock have created zones where oil can become trapped

Helical buckling of thin rods : FE modelling

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Bifurcation scenarios in helical buckling of slender rods using new FE

The authors would like to acknowledge the use of the Maxwell High Performance Computing Cluster of the University of Aberdeen IT Service and various industrial projects sponsored by Oil & Gas Innovation Centre (OGIC), which stipulated these studies.Peer reviewedPostprin

Suppression of drill-string stick–slip vibration by sliding mode control : Numerical and experimental studies

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On the Resistance Evaluation of Lateral-torsional Buckling of Bisymmetrical I-section Beams Using Finite Element Simulations

AbstractEvaluation of the lateral-torsional buckling resistance of bisymmetrical I-section beams using finite element method was widely discussed in the paper. Numerous FEM simulations with regard to the stability behavior of steel structural elements subjected to bending about the major principal axis were performed. The use of different finite element modeling techniques and their influence on obtained results were presented by the authors. The ultimate state of both perfect and imperfect elements was assessed. Considerations were concerned with hot-rolled wide flange HEB and narrow flange IPE section beams. Idealization of boundary conditions of FEM models complies with the assumptions used in the analytical formulation of stability problems of thin-walled beams. Geometrically and materially nonlinear analyses GMNA and GMNIA preceded by LBA analyses were carried out. Numerical simulations were conducted with use of ABAQUS/ Standard program

Complex dynamics of drill-strings : Theory and experiments

Peer reviewedPublisher PD