Insight Into the Heel–Toe Effect of a Long Horizontal Wellbore Based on a Hybrid Numerical Method

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Pranab N. Jha ◽  
Chuck Smith ◽  
Ralph W. Metcalfe
Keyword(s):  
Dynamic Behavior ◽  
Shale Gas ◽  
Initial Conditions ◽  
Fluid Flows ◽  
Flow Regimes ◽  
Lumped Parameter Model ◽  
Axial Distance ◽  
Gas Well ◽  
Lumped Parameter ◽  
Horizontal Wellbore

Numerical simulation of flow inside a horizontal wellbore with multiple completion stages is presented. Using a hybrid method combining computational fluid dynamics and a lumped parameter model, blocking effect on the toe-end stages observed in long horizontal wells (heel–toe effect) under simplified conditions is explained. A two-dimensional channel geometry was used to model the wellbore, with side inlets representing completion stages. First, using a five-stage well with steady state flow conditions, the existence of three basic flow regimes—trickle flow, partially blocked flow and fully blocked flow—was established. Using these results, the phenomenon of blocking of upstream inlets near the toe by the downstream ones near the heel is explained. The existence of these flow regimes is consistent with well-log data obtained from a horizontal shale gas well with 31 completion stages at two different times during production. Further, to study the dynamic behavior of the completion stages when reservoir fluid flows into the wellbore, a basic reservoir depletion model was created using a pressure boundary condition at the side inlets, varying in time. A lumped-parameter model was used to account for the pressure drop between two inlets separated by large axial distance. Different characteristic time scales, related to the depletion of the reservoirs, were identified. By varying initial conditions, the dynamic behavior of the system with multiple inlets was observed and analyzed. The transition of flow regimes with depletion of reservoirs is consistent with the observed behavior of the horizontal shale gas well.

Influence of assembly error and bearing elasticity on the dynamics of spur gear pair

2015 ◽  
Vol 230 (11) ◽  
pp. 1805-1818 ◽  
Author(s):  
Jianhong Wang ◽  
Jian Wang ◽  
Teik C Lim
Keyword(s):  
Finite Element ◽  
Dynamic Behavior ◽  
Transmission Error ◽  
Spur Gear ◽  
Lumped Parameter Model ◽  
Gear Pair ◽  
Tooth Contact ◽  
Lumped Parameter ◽  
Bearing Stiffness ◽  
Assembly Error

The elasticity and geometrical errors of precision elements are one of the major factors affecting vibration responses in geared transmission systems. In this study, the influences of assembly error and bearing elasticity on the spur gear dynamic behavior are analyzed. A lumped parameter model for spur gear pair is formulated by representing the bearing elasticity with infinitesimal spring elements and tooth stiffness time function as rectangular waveform. The nonuniform tooth contact load is also considered. The severity of assembly error is assumed to be sufficiently small such that no partial loss of tooth contact occurs. A harmonic balance method is applied to the resultant second-order partial differential equation governing the gear pair dynamic behavior. The variations of dynamic transmission error and tooth contact load with respect to mesh frequency for a set of bearing stiffness are analyzed. The influences of bearing stiffness on the dynamic transmission error are also evaluated. The variation of actual cross angle, an indicator on the tooth meshing state, is examined with respect to nominal cross angle and bearing stiffness. The analysis shows that the presence of bearing elasticity and assembly error can degenerate tooth contact significantly, and hence the appropriate specifications of bearing and mesh stiffness are critical at gearbox design stage. The analysis demonstrates that the proposed lumped parameter model can provide detailed contact information like finite element model, but it avoids finite element model’s prohibitive computation burden and can be completed easily and be computed quickly.

The Dynamic Simulations of Throttle Effect for Hydraulic Engine Mount

2012 ◽  
Vol 190-191 ◽  
pp. 847-851
Author(s):  
Yun Xia Zhang ◽  
Ting Hao ◽  
Zhi Min He
Keyword(s):  
Dynamic Behavior ◽  
Vibration Isolation ◽  
Numerical Results ◽  
Lumped Parameter Model ◽  
Dynamic Simulations ◽  
High Frequencies ◽  
Lumped Parameter ◽  
Engine Mount

A lumped parameter model is proposed for analysis of dynamic behavior of a Passive Hydraulic Engine Mount (PHEM) with incorporation of throttle, which is characterized by effective and efficient vibration isolation behavior in the range of both low and high frequencies. The experiments are made for the purpose of PHEM validation. The aim of simulation is to discuss the effect of throttle that the key parts of new mount. It has been shown by comparison of the numerical results with the experimental observations that the present PHEM with throttle achieves good performance for vibration isolation.

Numerical Study of Forward and Backward Whirling of Drill-String

2017 ◽  
Vol 12 (6) ◽  
Author(s):  
Marcin Kapitaniak ◽  
Vahid Vaziri ◽  
Joseph Páez Chávez ◽  
Marian Wiercigroch
Keyword(s):  
Chaotic Behavior ◽  
Initial Conditions ◽  
Numerical Study ◽  
Experimental Studies ◽  
Drill String ◽  
Lumped Parameter Model ◽  
Drilling Rig ◽  
Lateral Vibrations ◽  
Lumped Parameter ◽  
Theoretical Predictions

This work presents a numerical investigation of the undesired lateral vibrations (whirling) occurring in drill-strings, which is one of the main sources of losses in drilling applications. The numerical studies are conducted using a nonsmooth lumped parameter model, which has been calibrated based on a realistic experimental drilling rig. The numerical investigations are focused on identifying different types of whirling responses, including periodic and chaotic behavior, which have been previously observed experimentally. As a result, the parameter space is divided into different regions showing dynamically relevant responses of the model, with special interest on the influence of the mass and angular velocity of the drill-string system. In particular, the study reveals the coexistence of various types of whirling motion for a given set of parameters and their sensitivity to initial conditions. The obtained theoretical predictions confirm previous experimental studies carried out by the authors, which provides a solid basis for a better understanding of whirling phenomena in drill-string applications.

Economic benefit of shale gas exploitation based on back propagation neural network

2020 ◽  
Vol 39 (6) ◽  
pp. 8823-8830
Author(s):  
Jiafeng Li ◽  
Hui Hu ◽  
Xiang Li ◽  
Qian Jin ◽  
Tianhao Huang
Keyword(s):  
Neural Network ◽  
Shale Gas ◽  
Bp Neural Network ◽  
Large Scale ◽  
Linear Prediction ◽  
Back Propagation ◽  
Back Propagation Neural Network ◽  
Economic Benefits ◽  
Gas Well ◽  
Well Production

Under the influence of COVID-19, the economic benefits of shale gas development are greatly affected. With the large-scale development and utilization of shale gas in China, it is increasingly important to assess the economic impact of shale gas development. Therefore, this paper proposes a method for predicting the production of shale gas reservoirs, and uses back propagation (BP) neural network to nonlinearly fit reservoir reconstruction data to obtain shale gas well production forecasting models. Experiments show that compared with the traditional BP neural network, the proposed method can effectively improve the accuracy and stability of the prediction. There is a nonlinear correlation between reservoir reconstruction data and gas well production, which does not apply to traditional linear prediction methods

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