scholarly journals Identifiability of Location and Magnitude of Flow Barriers in Slightly Compressible Flow

2015 ◽  
Author(s):  
S. Kahrobaei ◽  
M. Mansoori ◽  
J.D. Jansen ◽  
G.J.P. Joosten ◽  
P.M.J. Van den Hof
Keyword(s):  
Compressible Flow ◽  
Slightly Compressible

Assessment of Free Surface Treatment Techniques and Turbulence Models Influence Using the Slightly Compressible Flow Simulation

2007 ◽  
Author(s):  
C. Ciortan ◽  
C. Guedes Soares ◽  
J. Wanderley
Keyword(s):  
Free Surface ◽  
Surface Treatment ◽  
Compressible Flow ◽  
Flow Simulation ◽  
Turbulence Models ◽  
Slightly Compressible ◽  
Eddy Simulation ◽  
Treatment Techniques ◽  
Flow Parameters ◽  
Wigley Hull

A free surface, finite-difference code on collocated grids, using the Slightly Compressible Flow formulation, is used for simulating turbulent flow around a Wigley hull. Two free-surface treatment techniques are compared in terms of accuracy and influence on the flow parameters. The runs were performed in standard conditions of Froude numbers and the results were compared against experimental and numerical results. The initial version of the code used an interface-tracking technique and two turbulence models (Large Eddy Simulation and Baldwin-Lomax). The numerical scheme was marched in time using the factorized Beam and Warming implicit method. The second version of the code uses an interface-capturing technique. For the time being, the code uses a fixed grid on which the kinematic free surface equation is solved. The grid is identical to the initial grid used in the first set of formulations. Other changes in the code were necessary, the most important being the switch of the time-marching method to a 2nd order, explicit Runge-Kutta. The results show good agreement with the experimental results.

scholarly journals Identifiability of Location and Magnitude of Flow Barriers in Slightly Compressible Flow

SPE Journal ◽  
2016 ◽  
Vol 21 (03) ◽  
pp. 0899-0908 ◽  
Author(s):  
S.. Kahrobaei ◽  
M.. Mansoori Habibabadi ◽  
G. J. Joosten ◽  
P. M. Van den Hof ◽  
J. D. Jansen
Keyword(s):  
Transfer Function ◽  
Compressible Flow ◽  
Time Domain ◽  
Production Data ◽  
Permeability Barrier ◽  
Low Permeability ◽  
Noise Levels ◽  
Large Reservoir ◽  
Slightly Compressible ◽  
Free Data

Summary Classic identifiability analysis of flow barriers in incompressible single-phase flow reveals that it is not possible to identify the location and permeability of low-permeability barriers from production data (wellbore pressures and rates), and that only averaged reservoir properties in between wells can be identified. We extend the classic analysis by including compressibility effects. We use two approaches: a twin experiment with synthetic production data for use with a time-domain parameter-estimation technique, and a transfer-function formalism in the form of bilaterally coupled four-ports allowing for an analysis in the frequency domain. We investigate the identifiability, from noisy production data, of the location and the magnitude of a low-permeability barrier to slightly compressible flow in a 1D configuration. We use an unregularized adjoint-based optimization scheme for the numerical time-domain estimation, by use of various levels of sensor noise, and confirm the results by use of the semianalytical transfer-function approach. Both the numerical and semianalytical results show that it is possible to identify the location and the magnitude of the permeability in the barrier from noise-free data. By introducing increasingly higher noise levels, the identifiability gradually deteriorates, but the location of the barrier remains identifiable for much-higher noise levels than the permeability. The shape of the objective-function surface, in normalized variables, indeed indicates a much-higher sensitivity of the well data to the location of the barrier than to its magnitude. These theoretical results appear to support the empirical finding that unregularized gradient-based history matching in large reservoir models, which is well-known to be a severely ill-posed problem, occasionally leads to useful results in the form of model-parameter updates with unrealistic magnitudes but indicating the correct location of model deficiencies.

Free Surface Flow Around Ship Hulls Using an Interface-Capturing Method

2008 ◽  
Author(s):  
C. Ciortan ◽  
C. Guedes Soares ◽  
J. Wanderley
Keyword(s):  
Free Surface ◽  
Boundary Conditions ◽  
Compressible Flow ◽  
Numerical Scheme ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Ship Hulls ◽  
Interface Capturing ◽  
Slightly Compressible ◽  
Surface Code

In the present paper, a compressible free surface code is used for simulating the flow around ship hulls. The code simulates both turbulent and laminar, free-surface flow around ship hulls, using the Slightly Compressible Flow formulation. The runs were performed for a Series60, Cb = 0.6 hull in standard conditions of Froude numbers and the results were compared against experimental and numerical results. The turbulence model used is Baldwin-Lomax. The numerical scheme was marched in time using the 2nd order, explicit Runge-Kutta. For the time being, the code uses a fixed grid on which the kinematic free surface equation is solved. Several boundary conditions were implemented and their behaviour assessed. The results show fair agreement with the experimental results.

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