A New Approach To Improve Linear Solver Performance for a Fully Implicit Coupled System of Reservoir and Surface Network

2013 ◽  
Author(s):  
Qinghua Wang ◽  
Graham Fleming ◽  
Qin Lu
Keyword(s):  
Coupled System ◽  
New Approach ◽  
Linear Solver ◽  
Fully Implicit ◽  
Surface Network ◽  
Solver Performance

A Semi-Implicit Approach for Integrated Reservoir and Surface-Network Simulation

2014 ◽  
Vol 17 (04) ◽  
pp. 559-571 ◽  
Author(s):  
Jialing Liang ◽  
Barry Rubin
Keyword(s):  
Explicit Knowledge ◽  
Coupled Model ◽  
Network Models ◽  
Computational Time ◽  
New Approach ◽  
Fully Implicit ◽  
Implicit Approach ◽  
Surface Network ◽  
Well Tests ◽  
Stability And Accuracy

Summary Conventionally, methods of coupling reservoirs and surface networks are categorized into implicit and explicit approaches. The term "implicit coupling" indicates that the two simulators solve unknowns together, simultaneously, or iteratively, whereas "explicit coupling" indicates that the two simulators solve unknowns sequentially and exchange their boundary conditions at the last coupled time tn. The explicit approach is straightforward to implement in existing reservoir and surface-network models and is widely used. Explicit coupling does have drawbacks, however, because well rate and pressure oscillations are often observed. In this paper, a new semi-implicit method for coupled simulation is presented. This technique stabilizes and improves the accuracy of the coupled model. The "semi-implicit coupling" overcomes the problems found in explicit-coupling methods without requiring the complexity of a fully implicit coupled model. The new approach predicts inflow-performance-relationship (IPR) curves at the next coupled time tn+1 by simultaneously conducting well tests for all wells in the reservoir before actually taking the required timestep. All wells first flow simultaneously to the next coupled time tn+1 with the well rates unchanged from the last coupled timestep. The timestep is rewound, and all well rates are reduced by a uniform fraction and then simultaneously flow again to tn+1. By extrapolating the resulting well pressures, the well's shut-in pressures at time tn+1 are determined, and thus, straight-line IPRs are produced. The new IPR curves approximate better each well's drainage region at tn+1 and each well's shut-in pressure at tn+1 which helps to stabilize the explicitly coupled model. The new coupling technique normally does not require iteration between the reservoir and surface network and normally has the stability and accuracy characteristics of an implicitly coupled approach. Because the well tests already account for individual well-drainage regions, an explicit knowledge of the well-drainage region is not required. Because of the stabilized IPR, the approach also was found to reduce the overall computational time compared with explicit coupling. Applications of the new approach are presented that show significant improvements surpassing explicit coupling in both stability and accuracy.

scholarly journals A Fully Implicit Finite Volume Scheme for a Seawater Intrusion Problem in Coastal Aquifers

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1639
Author(s):  
Abdelkrim Aharmouch ◽  
Brahim Amaziane ◽  
Mustapha El Ossmani ◽  
Khadija Talali
Keyword(s):  
Finite Volume ◽  
Coastal Aquifers ◽  
Nonlinear Partial Differential Equations ◽  
Time Integration ◽  
Mass Conservation ◽  
Coupled System ◽  
Finite Volume Scheme ◽  
Time Step ◽  
Volume Scheme ◽  
Fully Implicit

We present a numerical framework for efficiently simulating seawater flow in coastal aquifers using a finite volume method. The mathematical model consists of coupled and nonlinear partial differential equations. Difficulties arise from the nonlinear structure of the system and the complexity of natural fields, which results in complex aquifer geometries and heterogeneity in the hydraulic parameters. When numerically solving such a model, due to the mentioned feature, attempts to explicitly perform the time integration result in an excessively restricted stability condition on time step. An implicit method, which calculates the flow dynamics at each time step, is needed to overcome the stability problem of the time integration and mass conservation. A fully implicit finite volume scheme is developed to discretize the coupled system that allows the use of much longer time steps than explicit schemes. We have developed and implemented this scheme in a new module in the context of the open source platform DuMu X . The accuracy and effectiveness of this new module are demonstrated through numerical investigation for simulating the displacement of the sharp interface between saltwater and freshwater in groundwater flow. Lastly, numerical results of a realistic test case are presented to prove the efficiency and the performance of the method.

Linear Solver Performance Optimization in Reservoir Simulation Studies

2009 ◽  
Author(s):  
Ilya D. Mishev ◽  
Bret Loneil Beckner ◽  
Serge A. Terekhov ◽  
Nelli Fedorova
Keyword(s):  
Reservoir Simulation ◽  
Performance Optimization ◽  
Simulation Studies ◽  
Linear Solver ◽  
Solver Performance

Advances in Tightly Coupled Reservoir/ Wellbore/Surface-Network Simulation

2001 ◽  
Vol 4 (02) ◽  
pp. 114-120 ◽  
Author(s):  
V.J. Zapata ◽  
W.M. Brummett ◽  
M.E. Osborne ◽  
D.J. Van Nispen
Keyword(s):  
Simulation Model ◽  
Reservoir Simulation ◽  
Network Simulation ◽  
Simulation System ◽  
Model Description ◽  
Fully Implicit ◽  
Black Oil ◽  
Tightly Coupled ◽  
Surface Network ◽  
Reservoir Simulator

Summary One of the most perplexing and difficult challenges in the industry is deciding how to develop a new oil or gas field. It is necessary to estimate recoverable reserves, design the most efficient exploitation strategy, decide where and when to drill wells and install surface facilities, and predict the rate of production. This requires a clear understanding of energy distribution and fluid movements throughout the entire system, under any given operational scenario or market-demand situation. Even after a reservoir-development plan is selected, there are many possible facility designs, each with different investment and operating costs. An important, but not always considered, fact is that each facility scheme could result in different future production rates owing to various types, sizes, and configurations of fluid-flow facilities. Selecting the best design for the asset requires the most accurate production forecasts possible over the forecast life cycle. No other single technology has the ability to provide this insight, as well as tightly coupled reservoir and facility simulation, because it combines all pertinent geological and engineering data into a single, comprehensive, dynamic model of the entire oilfield flow system. An integrated oilfield simulation system accounts for all dynamic flow effects and provides a test environment for quickly and accurately comparing alternative designs. This paper provides a brief background of this technology and gives a review of a major development project where it is currently being applied. Finally, we describe some recent significant advances in the technology that make it more stable, accurate, and rigorous. Introduction Finite-difference reservoir simulation is widely used to predict production performance of oil and gas fields. This is usually done in a "stand-alone" mode, where individual well performance is commonly calculated from pregenerated multiphase wellbore flow tables that cover various ranges of wellhead and bottomhole pressures, gas/oil ratios (GOR's) and water/oil ratios (WOR's). The reservoir simulator determines the predicted production rate from these tables, normally assuming a fixed wellhead pressure and using a flowing bottomhole pressure calculated by the reservoir simulator. With this scheme it is not possible to consider the changing flow-resistance effects of the piping system as various fluids merge or split in the surface network. Neglecting this interaction of the surface network can, in many cases, introduce substantial errors into predicted performance. Basing multimillion- (in some cases, billion-) dollar exploitation designs on performance predictions that are suboptimal can be very detrimental to the asset's long-range profitability. To help eliminate this problem, considerable attention is being given to coupling reservoir simulators and multiphase facility network simulators to improve the accuracy of forecasting. Landscape Surface-network simulation technology was first introduced in 1976.1 Although successfully applied in selected cases, the concept was not widely adopted because of the excessive additional computing demands on computers of that era. In those earlier applications, the time consumed by the facility calculations could actually exceed the reservoir calculations.2,3 As computer performance has increased by orders of magnitude, this has become less of an issue. Reservoir model sizes have increased dramatically with much finer grids that take advantage of the increased computer power, but there was no need for a corresponding increase in the size of the facility models. Today, with tightly coupled reservoir/wellbore/surface models, the facility calculations are a fairly small part of the overall computing time and there is considerable effort in the industry to build these types of systems.4,5 Chevron's current tightly coupled oilfield simulation system is CHEARS®***/PIPESOFT-2™****. CHEARS® is a fully implicit 3D reservoir simulator with black-oil, compositional, thermal, miscible, and polymer formulations. It has fully implicit dual porosity, dual permeability options, and unlimited multiple-level local grid refinement. PIPESOFT-2™ is a comprehensive multiphase wellbore/surface-network simulator. It has black-oil, compositional, CO2, steam, and non-Newtonian fluid capabilities. It can solve any type of complex nested looping, both surface and subsurface. The coupling is done at the wellbore completion interval, which is the natural domain boundary between the flow systems. We refer to our implementation as "tightly coupled" because information is dynamically exchanged directly between the simulators without any intermediate intervention. A simple representation of the interaction between the simulators is shown in Fig. 1. Gorgon Field Example The following is an example of how this technology is currently being used. The Gorgon field is a Triassic gas accumulation estimated to contain over 20 Tscf of gas, located 130 km offshore northwest Australia in 300 m of water (Fig. 2). It is currently undergoing development studies for an LNG project. Field and Model Description. The field is 45 km long and 9 km wide, and it comprises more than 2000 m of Triassic fluvial Mungaroo formation in angular discordance with a Jurassic-age unconformity. It has been subdivided into 11 vertical intervals (or zones) on the basis of regional sequence boundaries and depositional systems. These 11 zones were first modeled individually with an object-based modeling technique before being stacked into a 715-layer full-field geologic model. This model was subsequently scaled up to a 46-layer reservoir simulation model, reducing the size of the model from 4.5 million cells to 290,000 cells. While the scaleup process preserved the original 11 zone boundaries, the majority of the layers were located in regions identified as key flow units. In addition to vertical subdivision, seismic and appraisal well data suggest structural compartmentalization, resulting in six major fault blocks. After deactivating appropriate cells, the final simulation model contained 50,000 active cells and was initialized with 35 independent pressure regions. Each of these regions corresponds to a single zone in a single fault block.

scholarly journals Linear solver performance in elastoplastic problem solution on GPU cluster

2017 ◽  
Author(s):  
Yu. V. Khalevitsky ◽  
A. V. Konovalov ◽  
N. V. Burmasheva ◽  
A. S. Partin
Keyword(s):  
Elastoplastic Problem ◽  
Problem Solution ◽  
Gpu Cluster ◽  
Linear Solver ◽  
Solver Performance

scholarly journals Mass splitting in an 331-TC coupled scenario

2020 ◽  
Vol 35 (27) ◽  
pp. 2050169
Author(s):  
A. Doff
Keyword(s):  
Asymptotic Behavior ◽  
Coupled System ◽  
Mass Splitting ◽  
Mass Scale ◽  
Third Generation ◽  
New Approach ◽  
High Energies ◽  
Fermion Masses ◽  
Irregular Form ◽  
Very High

The root of most of the technicolor (TC) problems lies in the way the ordinary fermions acquire their masses, where an ordinary fermion [Formula: see text] couples to a technifermion [Formula: see text] mediated by an extended technicolor (ETC) boson leading to fermion masses that vary with the ETC mass scale [Formula: see text] as [Formula: see text]. Recently, we discussed a new approach consisting of models where TC and QCD are coupled through a larger theory, in this case the solutions of these equations are modified compared to those of the isolated equations, and TC and QCD self-energies are of the irregular form, which allows us to build models where ETC boson masses can be pushed to very high energies. In this work we extend these results for 331-TC models, in particular considering a coupled system of Schwinger–Dyson equations, we show that all technifermions of the model exhibit the same asymptotic behavior for TC self-energies. As an application we discuss how the mass splitting of the order [Formula: see text](100) GeV could be generated between the second and third generation of fermions.

scholarly journals On Improving Linear Solver Performance: A Block Variant of GMRES

2006 ◽  
Vol 27 (5) ◽  
pp. 1608-1626 ◽  
Author(s):  
A. H. Baker ◽  
J. M. Dennis ◽  
E. R. Jessup
Keyword(s):  
Linear Solver ◽  
Solver Performance

scholarly journals Finite Difference Analysis of Unsteady Heat and Flow of an Incompressible Third Grade Fluid

2021 ◽  
pp. 307-318
Author(s):  
I Nayak
Keyword(s):  
Finite Difference ◽  
Viscous Dissipation ◽  
High Speed ◽  
Transfer Problem ◽  
Coupled System ◽  
Elastic Parameter ◽  
Physical Parameters ◽  
Fully Implicit ◽  
Grade Fluid ◽  
Matlab Programming

An unsteady flow and heat transfer problem with viscous dissipation of a third order fluid placed within two long parallel flat porous walls is studied in present work. The governing equations are non- dimensionalized and finally a non-linear coupled system of partial differential equation is obtained. An approximated solution is obtained using finite difference method of fully implicit form. With help of high speed MATLAB programming numerical solution is procured and presented graphically. Investigation is made on effect of different physical parameters on flow and heat profile. The notable finding in the current work is that for smaller values of visco-elastic parameter ®, the velocity rises with raising the values of ®. But for larger visco-elastic parametric values of ®, a reversed effect is seen on velocity field. Also with the increase of viscous-dissipation parameter, more viscous-dissipation heat generated that increases the temperature field.

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

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