... rates decrease with a diminishing bottom hole pressure and the flow starts oscillating at an increasing amplitude. After reaching the bubble point value, the gas starts releasing at the lateral section and slugs start to form, merge and travel through the vertical section before reaching the wellhead...

.... Direct shear tests of rough (RMS = 500 μm) and smooth (RMS = 7 μm) surfaces in Gabbro are performed under a constant normal stress of 5 MPa and a constant shear displacement rate of 0.01 mm/s. All four direct shear experiments exhibit stick-slip oscillations once reaching "steady state" sliding...

... Artificial Intelligence drillstring dynamics germay Upstream Oil & Gas oscillation bit selection drilling operation stability analysis stability Detournay time delay drilling system rgd model partial blade stability map besselink linear stability analysis bit design symmetric bit state...

... oscillation at interfaces of a composite material where a vast difference of conductivity property is observed and cannot guarantee local mass conservation with the classical form (Haga et al., 2012; Lee et al., 2017). This problem affects not only velocity calculation and coupling with the transport equation...

... reaction instability within rock destruction is associated with non-homogeneity or considered self- excited (T. Richard, C. Germay, E. Detournay, 2004), but no clear relations between material homogeneity characteristics and rock reaction force oscillations were proposed. In the frame of drilling, rock...

... equation rotation speed configuration timescale perturbation critical speed upstream oil & gas instability steady-state response rgd model stability analysis oscillation vibration rotary drilling system correspond stick-slip instability regime unstable pole drilling...

... involved in the rock cutting machines. This paper describes one of the advanced cutting technologies called the oscillating disc cutting for hard rock cutting and its advantages over other cutting systems are highlighted by comparing the results with that of conventional disc cutting technique employed...

... ABSTRACT: Drilling operation with Polycrystalline Diamond Compact (PDC) bit constitutes vertical oscillations which can both negatively and positively influence the efficiency of the penetration. In order to study the effect of bit vertical vibration in performance of PDC bits, a single PDC...

... axial stress stress oscillation MPa nonlinearity Upstream Oil & Gas net stress specimen saturation Reservoir Characterization pore pressure Castlegate sandstone polarization reservoir geomechanics nonlinear response Nonlinear Elasticity propagation oscillation Pore Fluid...

... and vertical forces acting on the cutter oscillate and reach to a maximum just before a major chip forms [1]. This is a true conclusion in the sense that a fracture path in the rock in front of the cutter forms which produces the chip. And analytically they are similar to logarithmic spirals [2...

... Dynamics oscillation procedure formulation stabilization mechanics finite element 1. INTRODUCTION In coupled poromechanics problems finite elements sometimes exhibit pressure oscillations when very small time steps are used. These oscillations can be caused by a) the incompressibility constraint...

... of a fluid invading a pre-existing fracture, Fresnel oscillations can be used as an internal calibration when no reference sample exists. INTRODUCTION In many engineering applications, dynamic processes result in the propagation of a front, i.e., a discontinuity in material property that sweeps through...

... ABSTRACT The large diameter split pressure Hopkinson bar (SHPB) is an important tool to obtain the dynamic mechanical properties of brittle materials such as rocks. There are at least three disadvantages when it is used for testing rocks. These are: (1) strong oscillation and dispersion...

... at confining pressures from 30 MPa to 110 MPa. Induced by cumulative slip or load point velocity perturbation, the transition from stable sliding to cyclic stick-slip might involve several distinct sliding modes, including chaotic oscillations, period doubling and self-sustained oscillations. Nonlinear...

... by a displacement in the vertical direction (normal). Con- traction is also possible and is the closing of the joint due to large normal stresses. Upstream Oil & Gas displacement oscillation direct shear test Artificial Intelligence strength roughness shear behavior shear strength test result...

...26th US Symposium on Rock Mechanics/Rapid City, SD / 26-28 June 1985 The effect of hydraulic-fracture growth on free oscillations of wellbore pressure GARY R.HOLZHAUSEN Applied Geomechanics Inc., Santa Cruz, California, USA RICHARD P. GOOCH Department of Electrical Engineering, Stanford University...

...- ly independent of volume V 0. The system would behave like a simple pendulum of the same length as the drilling hole. By disregarding g/Z we obtain 0 = 1/]2 per second and the period of the oscillations is about one minute. This period is long enough for the phenomenon considered to be easily dis...