bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coalbed Methane Simulator Development for Improved Recovery of Coalbed Methane and CO2 Sequestration
Authors: Syahrial E. 
Published: December 2007

Proposal
Sequestration of CO2 in deep unmined coal seams is currently under development for improved recovery of coalbed methane (ICBM) as well as permanent storage of CO2. Recent studies have shown that CO2 displaces methane by adsorbing more readily onto the coal matrix compared to other greenhouse gases, and could therefore contribute towards reducing global warming. In order to carry out a more accurate assessment of the potential of ICBM and CO2 sequestration, field based numerical simulations are required. Existing simulators for primary CBM (coalbed methane) recovery cannot be applied since the process of CO2 injection in partially desorbed coalbeds is highly complex and not fully understood. The principal challenges encountered in numerical modelling of ICBM/CO2 sequestration processes which need to be solved include: (1) two-phase flow, (2) multiple gas components, (3) impact of coal matrix swelling and shrinkage on permeability, and (4) mixed gas sorption.
This paper describes the development of a compositional simulator for improved recovery of coalbed methane and CO2 sequestration. The new features that describe the complex process of CO2 injection are implemented here. The numerical results for enhanced recovery indicate that matrix swelling associated with CO2 injection could results in more than an order of magnitude reduction in formation permeability around the injection well, hence prompt decline in well injectivity. The model prediction of the decline in well injectivity is consistent with the reported field observations in San Juan Basin USA. Also, a parametric study is conducted using this simulator to investigate the effects of coal properties on the enhancement of methane production efficiency based on published data.
Integrated Analysis of Down-hole Corrosion Logs to Investigate Casing Leaks
Authors: Al-Ghasham Y. Y. , Catte D. R. , Al-Haji A. A. 
Published: December 2007

Abstract
Despite the application of impressed current cathodic protection (ICCP), the Hawiyah and Haradh areas in the Ghawar field of Saudi Arabia have experienced external corrosion-related casing leaks through relatively shallow aquifers in a number of water injection wells.Many of the wells with failures were less than 10 years old and required costly workover repairs.
Down-hole corrosion logs were ran in these wells and others to investigate the cause(s) and mechanism(s) of the casing leaks.The logs were run under dynamic cathodic protection conditions to develop a better understanding of the problem and to enable the authors to determine cost-effective preventive measures to reduce future failures.
This paper presents a detailed analysis of the investigative corrosion logs, which include ultrasound, electromagnetic and potential measurement type logs. Findings will focus on cement quality, electrochemical interference between offset wells, and the effects of changing the magnitude of the applied cathodic protection current.
Sustainable Management of a Large Oil Field in Libya
Authors: Bremeier M. , Elashahab B. M. , Goh T. 
Published: December 2007

Abstract
This paper presents the efficient implementation of an integrated reservoir-management strategy with the example of a large oil field in the Sirte basin. The reservoir-management strategy targets a recovery factor in excess of 50% in line with high HSE standards such as gas utilization and produced salt water re-injection.
The immediate evaluation of key uncertainties, a focused data acquisition programme and proper data analysis enabled the early identification of optimisation potential. A tarmat at the initial oil-water contact was identified at a very early stage and detailed special core analysis led to the correct prediction of its threshold pressure. The encroachment of the bottom drive aquifer and the tilting dynamic oil-water contact was correctly forecasted by reservoir simulation. In conclusion, a substantial modification of the initial development plan was implemented.
A production optimisation strategy of ‘edge-to-top-displacement’ was selected. With a balance of off-take and pressure support, the recovery of down-dip wells was optimised in advance. The steering of the tilted secondary oil-water contact was monitored by reservoir surveillance, i.e. pressure and saturation monitoring. Reservoir simulation was again efficiently used and enabled the exact prediction of different recovery strategies. This also incorporated the management of water shut-off's in producing wells.
Artificial gas-lift was implemented to optimise recovery of wells with high water-cuts. Detailed interaction between different disciplines resulted in a modification of the standard API gas-lift design with considerable improvements.
The sustainable reservoir-management of the As Sarah oilfield is based on tailor-made data acquisition and state-of-the-art analysis and interpretation. With an integrated approach, including all relevant disciplines, it was possible to implement a custom-made development schedule resulting in a remarkable recovery factor.
Compact separation By Means of Inline Technology
Authors: Schook R. , van Asperen V. 
Published: December 2007

Abstract
In a conventional separator, with the exception of mist elimination, separation is usually achieved by allowing the fluids to have a few minutes retention time under the influence of gravity. Separation equipment can be reduced in size bythe application of a centrifugal force, which is many times gravity. The result of this is that centrifugal separators can be manufactured as a very compact unit. One step further is to fabricate the equipment according to pipeline design codes so as to avoid the complexities associated with the use of pressure vessels. Inline separators are based on cyclonic technology and can be regarded as mono-cyclones. At the moment two types of separators are available and qualified for the market. The first one is a Degasser where the aim is to separate gas from a liquid continuous flow. The second type is a Deliquidiser acting in the opposite way namely separating liquid from a continuous gas stream. Besides this, liquid/liquid inline separators are in development at the moment. Besides the compactness of these inline separators, the flexibility in terms of turndown, pressure drop and efficiency is a significant benefit compared to conventional separation equipment. The paper describes several types of newly developed inline separators and inline separator-systems. In addition current installations, namely those on Statoil Statfjord B and Sleipner T platform and on the BP ETAP platform, along with their specific benefits and cost savings are discussed. It will be shown that inline technology can and has played a major role in the de-bottlenecking and upgrading of existing top-side facilities. Besides this several sub-sea applications on new and existing oil and gas fields are currently being assessed for the application of this inline technology.
Optimizing Stimulation of Coalbed Methane Reservoirs Using an Integrated Fracture Modeling Approach
Authors: Valencia K. J. , Chen Z. , Hodge M. O. , Rahman S. S. 
Published: December 2007

Abstract
Conventional methodologies have failed to address the difficulties involved in the design and execution of fracture treatments of reservoirs with complex geology and stress conditions such as coal bed methane (CBM) reservoirs. This paper presents an innovative technique to optimize and design hydraulic fracture treatments in naturally fractured CBM reservoirs. This methodology integrates (1) a three dimensional (3D), finite element based numerical design tool to predict the fracture geometry for given reservoir and operating conditions, (2) a production model to estimate fluid flow in the CBM reservoir, and (3) cost analysis to optimize the design parameters against different field scenarios using a hybrid genetic-evolutionary optimization tool.
The technique has been used to design fracture treatments in a coal bed methane reservoir to illustrate its potential benefits in improving the reservoir's productivity. Results of this study have shown that the use of a 3D geometry model enabled realistic post-frac productivity analysis. This provided reliable conservative estimates on the revenue derived from the stimulation program. Furthermore, the optimization approach allowed operators to incorporate operating constraints based on sound industry practice and company guidelines for a cost-effective exploitation of CBM reservoirs.
Optimization and Scaling of Reservoir Models
Authors: Lenoach B. , Bowen G. 
Published: December 2007

Abstract
We report on an investigation into optimization techniques that could be useful for the automatic matching of production data. One key objective is to extract the maximum amount of information from the data. Our starting point is a series of grids of differing refinement starting at a coarse scale and an associated set of property parameterizations at increasing resolutions. Automatic optimization algorithms are investigated that utilize the differing scales. The aim is to develop optimization methods that can extract maximum information from the production data and are fast and robust enough for practical use.
The algorithms written for this study, which were initially developed for stand-alone single-phase flow models, have subsequently been implemented in a system using a standard commercial simulator. The results presented here are for synthetic models using a simulated truth case; the models are introduced in order of increasing levels of realism.
Three-Dimensional, Three-Phase Discrete-Fracture Reservoir Simulator Based on Control Volume Finite Element (CVFE) Formulation
Authors: Fu Y. , Yang Y. -K. , Deo M. 
Published: December 2007

Proposal
A three-dimensional, three-phase black oil reservoir simulator has been developed using the Control Volume Finite Element (CVFE) formulation. Flux-based upstream weighting is necessary to ensure flux continuity and solution stability. Traditional CVFE formulations for reservoir simulation are not flux continuous. Flux continuity is observed with respect to all the phases; the solutions are locally and globally mass conservative. In addition, numerical aspects of the problem are not any more complicated than the finite- difference techniques, since numerical integration of dependent variables in the control volume is not required. It is thus established that CVFE formulation can be employed for field-wide reservoir simulation as an alternative to finite- difference formulations. Comparison of the results to results from a finite-difference simulator is presented.
The formulation is fully implicit. State-of-the-art parallel, linear solvers (coupling with the Portable Extensible Toolkit for Scientific Computation (PETSc)) are used. The simulator is appropriate for reservoirs of complex geometry. The formulation is applicable to anisotropic and heterogeneous domains, with full-tensor permeability. Fractures and faults are represented by lines (in two dimensions) and planes (in three dimensions). The difficult task of generating an unstructured mesh for complex domains with faults and fractures is accomplished in this study. Results of two-phase and three-phase simulations in a variety of fractured/faulted and nonfractured domains are presented. These domains are geometrically complex and are not easily represented by traditional finite-difference discretization. Fundamental aspects of fracture flow mechanics, such as imbibition, water bypassing, etc. are more easily examined using these simulators. Capillary pressure functions in matrix and fractures are very important in determining recovery behavior. Different combinations of capillary pressures in matrix and fractures can be examined with these models. The models were implemented in parallel on a 18-processor Linux cluster (64-bit Opteron chips) using Message Passing Interface (MPI). Speedup of up to 12 on a 16-processor setup was observed.
Dual-Mesh Simulation of Reservoir Heterogeneity in Single-and Dual-Porosity Problems
Authors: Atan S. , Al-Matrook M. , Kazemi H. , Ozkan E. , Gardner M. 
Published: December 2007

Abstract
This paper presents dual-mesh computing in simulation of reservoir heterogeneities in single- and dual-porosity reservoirs. The dual-mesh approach provides a great tool for computing displacement processes and saturation distribution on the same fine-grid as the underlying geological models and is also extremely powerful in simulation of naturally fractured, dual-porosity reservoirs. This approach may even be used for the fine-scale computations in compositional modeling of petroleum reservoirs. In principle, the dual-mesh computing surpasses the benefits of streamline simulation both in single and dual-porosity problems. Several convincing examples are presented to illustrate the broad applications. The reasons for the accuracy and efficacy of the dual-meash computing are also explained.
Simulating Residual Oil Saturation in Miscible Gas Flooding Using Alpha-Factors
Authors: Barker J. W. , Prévost M. , Pitrat E. 
Published: December 2007

Abstract
A method for imposing residual oil saturation in compositional simulation of miscible gas injection processes is proposed. It is based on use of alpha-factors found by a simple analytic calculation.
The method is validated on a one-dimensional model, then applied to full field simulations of miscible gas injection in the Deep Jusepin reservoir in Venezuela. In this case, the alpha-factor approach was judged to have been successful, improving the physical representation of the process and probably making the simulation results more realistic.
Finally, the method is compared with other possible approaches, principally (a) excluding a specified amount of oil from the flash calculations, or (b) using a dual porosity model.
Precambrian Field Oman from Greenfield to EOR
Authors: Al-Riyamy Q. , Kelly S. , Al-Rawahi A. , Matsuura T. , Davis D. , Henning R. , Terres R. 
Published: December 2007

Abstract
A group (the Cluster) of nine intra-salt Precambrian age reservoirs is located in the south of Oman 70 km from the nearest infrastructure and has been identified for potential development. Four reservoirs are currently producing via depletion. Although primary depletion provides a robust and economic development, Petroleum Development Oman (PDO) intends to implement a development based on EOR miscible gasflood at the earliest opportunity. If successful, a miscible gas injection project has the potential to triple the ultimate recovery compared to primary depletion. In order to demonstrate the technical feasibility and economic viability of a miscible gasflood, one of the identified Precambrian reservoirs (Field A) was extensively modelled both statically and dynamically.
A complete subsurface reservoir characterization was underpinned with an extensive data acquisition program, including: new 3D seismic acquisition and processing, full-reservoir section coring and sedimentologic facies description, routine and special core analyses, standard wireline logging, bore-hole image logs and interpretation, well test data (stimulation and cleanup, stabilized flow test, pressure buildup, MPLT, and standard and miscible PVT analyses) and interference pressure testing (from permanent down-hole pressure gauges).
Integrated static and dynamic compositional modelling of the field identified the primary subsurface uncertainties as: compartmentalization, permeability heterogeneity and injectant gas composition (to achieve miscibility). Pressure interference results indicate that faults locally act as baffles (not barriers) and that no field wide thief zone is present. Miscible PVT experiments show that an average Cluster gas should be multiple contact miscible at pressures below original reservoir pressure.
A comprehensive suite of geological static model realizations and compositional dynamic simulations were generated to capture the spread in reservoir heterogeneity, STOIIP and ultimate recovery. Gasflood recovery factors from these full field simulations varied from 25% to 55% and demonstrated that a miscible gasflood in this reservoir is attractive even in the pessimistic case. Field A will be the first miscible gasflood in the Cluster. Based on the studies approval have been given to develop the field with miscible gasflood
An Adaptive Multiphase Multiscale Finite Volume Simulator for Heterogeneous Reservoirs
Authors: Tchelepi H. A. , Jenny P. , Lee S. H. , Wolfsteiner C. 
Published: December 2007

Abstract
We developed an adaptive reservoir simulator for accurate modeling of multiphase flow and transport in large scale heterogeneous reservoirs. The simulator is based on a multiscale finite volume (MSFV) method. We describe both IMPES and sequential implicit formulations. The algorithms are sensitive to the specific characteristics of flow (i.e., pressure and total velocity) and transport (i.e., saturation). To obtain the fine scale (i.e., fine grid) flow field, two sets of basis functions - dual and primal - are constructed. The dual basis functions, which are associated with the dual coarse grid, are used to calculate the coarse scale transmissibilities. The fine scale pressure field is computed from the coarse grid pressure via superposition of the dual basis functions. Having a locally conservative fine scale velocity field is essential for accurate solution of the saturation equations (i.e., transport). The primal basis functions, which are associated with the primal coarse grid, are constructed for that purpose. The dual basis functions serve as boundary conditions to the primal basis functions. To resolve the fine scale flow field in and around wells, a special well basis function is devised. As with the other basis functions, we ensure that the support for the well basis is local.
Our MSFV simulator is designed for adaptive computation of both flow and transport in the course of a simulation run. Adaptive computation of the flow field is based on the time change of the total mobility field and triggers selective updates of basis functions. The key to achieving scalable (efficient for large problems) adaptive computation of flow and transport is the use of high fidelity basis functions with local support. We demonstrate the robustness and computational efficiency of the MSFV simulator using a variety of large heterogeneous reservoir models, including the SPE 10 comparative solution problem.
Finite Volume Methods for Coupled Stress/Fluid Flow in a Commercial Reservoir Simulator
Authors: Shaw G. , Stone T. 
Published: December 2007

Abstract
The flow equations in commercial reservoir simulators are generally discretized using the finite difference method, whereas for stress equations it is more common to use the finite element approach. In a reservoir simulator designed to include geomechanical effects, these two distinct types of equations must be solved with some degree of coupling. It is therefore natural to ask whether suitable finite volume methods can be derived for the stress equations - so that the stress and fluid flow models can share a common derivation, and what are the relative merits of finite volume and finite element methods for these coupled systems.
In this paper we present a finite volume discretization of the stress equations as implemented in a commercial reservoir simulator with an option to couple the stress with the fluid flow. We demonstrate that the method is locally conservative and retains second order accuracy on general threedimensional grids. We discuss the imposition of various types of boundary condition and describe the implementation of special features such as faults, pinch-outs and local grid refinements. We also present a comparison with other approaches based on finite differences1,2 and finite elements3. The relative accuracy, efficiency and robustness of these three different approaches are discussed.
Finally the paper presents some case studies demonstrating the suitability of the finite volume approach for realistic geomechanical simulations.
Water Management in North ‘Ain Dar, Saudi Arabia
Authors: Alhuthali A. H. , Al-Awami H. H. , Soremi A. , Al-Towailib A. I. 
Published: December 2007

Abstract
This paper presents a study on a six-year water management strategy in North ‘Ain Dar to reduce water production, prolong well life and enhance oil recovery. This field has been under peripheral injection for more than thirty years. Three strategies were implemented during the past five years to achieve optimal water management: 1) production optimization, 2) rigless water shutoff jobs, and 3) horizontal drilling. The success of these strategies can be attributed to a full understanding of the drive mechanisms that control fluid transport in the reservoir. This paper presents these mechanisms and their impact on water management strategies. The effectiveness of these strategies have been evaluated and supported by field data.
Horizontal drilling and rigless water shut-off proved to be effective techniques to control water production and enhance recovery in this gravity dominated system. Since 1999, production optimization has also played a significant role in controlling the water production and maintaining a constant water cut.
Effective Integration of Reservoir Heterogeneities, Fracture Networks and Fault Communication and Their Challenges in Bahrain Field Simulation Models
Authors: Kumar K. , Abdulwahab A. E. , AL-Muftah A. 
Published: December 2007

Abstract
The Bahrain field is an asymmetric anticline trending in the North-South direction. The field was discovered in 1932. The field is a multi-stack carbonate and sandstone reservoirs most of them oil bearing. The fluids range from tarry oil in Aruma zone to dry gas in the Khuff zones. The geology of the field is extremely complex with a large number of faults especially in the Wasia group formations, which contain the major oil reservoirs of the Bahrain field. These reservoirs are at different stages of the production cycle. Following a 3-D seismic acquisition campaign in the year 2000, Bapco took up an integrated study to develop numerical models as the main tool to assess alternative production mechanisms. This integrated study faced a significant number of challenges, which had to be overcome with innovative ideas.
The challenges included representing communication between reservoirs through faults, complex rock and fluid distribution from heavy oil to condensate, gas injection, aquifer encroachment and fracture intensity. Although the hardware required for handling the large simulation models was meticulously selected based on benchmark data of the various machines, the geological complexities posed serious problems while running the simulation models.
This paper describes the effective integration of the reservoir heterogeneities, fracture networks and fault communication in the simulation models built for different zones of Bahrain field. It also highlights the challenges faced during history matching process and the approaches adopted to overcome these challenges.