bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preventing Shallow Gas Migration in Offshore Wells: The Performance of Lead Cements
Authors: Coker O. D. , Harris K. L. , Williams T. A. 
Published: December 2007

ABSTRACT
Offshore drilling operations that encounter shallow gas formations must consider the potential annular gas flow that may occur following primary cementing. Many specialized cements and procedures have been developed to combat gas migration, but the complexities of gas migration control still challenge operators worldwide. In offshore shallow environments, additional complications can arise with the presence of weak formations and cold temperatures. In such conditions, lightweight lead cements are employed to avoid fracturing the wellbore. Although lead cements are often viewed simply as "filler" materials, shallow gas control slurries must far exceed that role as they become the mechanism to help isolate the movement of gas up the annulus.
Presented in this paper is a review of the properties of gas control cementing systems specifically related to lightweight lead slurries. The importance of fluid loss control, rapid gelation, and compressive strength at the time of drillout is stressed. Silica fume cement and newer cementing additives such as colloidal silica and small particle cement are highlighted as means of helping prevent shallow gas migration. Several offshore cementing operations are documented which confirm the success of applying the prescribed designs and methods.
High-Energy Gas Fracturing (HEGF) Technology: Research and Application
Authors: Yang Weiyu , Zhou Chunhu , Qin Fadong , Li Dang 
Published: December 2007

ABSTRACT
HEGF is an oil/gas well stimulation technology by means of propellant inflamming in wells to produce multiple radial fractures in formation and hence to enhance the well production. The paper summarizes the achievements of our effort on research and application of the technology. For understanding the HEGF mechanism, laboratory and field experiments are conducted and numerical simulators are studied. The treatment design method and implementation techniques are discussed. A design software, which includes the content of propellant burn, perforation, stemming liquid motion, fracture propagation, fluid flow in fracture, and production increase prediction etc., has been developed to serve as the basis of the design, optimization, and control of the technology. The application of the technology to exploratory, production and injection wells shows its great prospects in oil and gas industry.
Stimulation of High-Rate Gravel-Packed Oil Wells Damaged by Clay and Fines Migration: A Case Study, Gullfaks Field, North Sea
Authors: Svendsen O. B. , Kleven Reidun , Hartley I. P. R. , Aksnes Norvald 
Published: December 2007

ABSTRACT
This paper reviews the methodology and approach taken to stimulate oil production from high rate gravel packed wells in a high permeability poorly consolidated sandstone reservoir, containing up to 35% clay fines. The three key elements involved were; a detailed laboratory study to identify and quantity the damage mechanism, selection of an optimum treatment fluid system, and finally successful execution through accurate placement of the treatment fluids.
Reservoir Management of the Oseberg Field After Four Years’ Production History
Authors: Fantoft Svein 
Published: December 2007

ABSTRACT
The Oseberg Field comprises an accumulation about 500 × 106 Sm3 of oil and 60 × 109 Sm3 of free gas located in seven partly communicating reservoirs. Oseberg experiences full scale gas injection supplied by water injection in some reservoir units. Production experiences and observation wells have confirmed gravity stable displacement at high offtake rates. History matched simulation models indicate that oil recovery above 60% may be obtained in the main reservoir unite. An extensive horizontal well program will give important contributions to a prolonged plateau period and high recovery.
Transforming the Future of the Brent Field: Depressurisation—The Next Development Phase
Authors: Braithwaite C. I. M. , Schulte W. M. 
Published: December 2007

ABSTRACT
Under waterflood development, gas production from the Brent Field will fall off plateau in 1998 and, at field abandonment, it is estimated that approximately 55% of the 6.9 Tscf GIIP and 54% of the 3600 MMstb STOIIP would be recovered.
With its high solution gas-oil-ratio, reservoir depressurisation, as an enhanced recovery project, is an attractive possibility. In this process, reservoir pressures would be progressively lowered, ultimately to approximately 1000 psi.
It is expected that gas liberated from residual and by-passed oil would increase gas recovery by over 1 Tscf allowing the field to continue to produce at plateau levels into the 21st Century. Depressurisation is also expected to increase oil and condensate recovery by 30 MMstb compared to a continuation of the ongoing waterflood. From a sub-surface viewpoint, the main challenge would be to manage the field to maximise oil recovery while maintaining gas sales at plateau.
To allow the field to move into a new development phase, an extensive platform modification programme will need to be initiated. Planning has to take into account the uncertainties associated with a project that has not been tried on an oil reservoir of such a scale. Aquifer influx, H2S and sand production are some of the risks that have been assessed and contingency measures identified.
Investigation of Optimum Well Spacing for North Sea Eocene Reservoirs
Authors: Matthews J. D. , Carter J. N. , Dake L. P. 
Published: December 2007

Abstract
Eocene reservoirs contain thin columns of high viscosity oil. Recovering the oil is difficult because coning results in low oil production rates.
This paper examines the effect of drilling wells on a much smaller spacing than is traditionally employed in the North Sea. It is found that smaller spacings improve oil recovery.
The Bruce Gas Export Line Tie-In Into the Frigg UK Line by Means of the Tomseal Isolation Technique
Authors: Freund J. P. , Vossier Bernard 
Published: December 2007

ABSTRACT
The Bruce field is a large gas condensate accumulation, which underlies blocks 9/8a, 9/9a and 9/9b in the UK sector of the North Sea. The decision to develop the Bruce field was taken by the Bruce Partners (BP Exploration, Elf UK, Total Oil Marine, Hamilton and LASMO North Sea) in 1989, and the responsibility for gas transportation was assigned to Total Oil Marine, as operator.
In November 1989, TOTAL formed a project group, which was set up to study, design, construct and install the Frigg UK Wye Project, besides other responsibilities within the Bruce Area Development Project developed by B.P. In the actual economic context calling for cost effective developments, the project group conceived, engineered, tested and deployed a new pipeline isolation philosophy: TOMSEAL, which is based on a combination of proven hot tapping and folding stopple techniques associated with the development of new remotely controlled plugs, for the tie-in of the Wye piece into the Frigg UK line. TOMSEAL makes lengthy recommissioning redundant as it avoids the need for pipeline flooding, dewatering and drying, therefore generating cost savings on the connection operations but, more importantly, shortening dramatically gas export transportation system unavailability when performing the connection.
Once the works are commissioned in 1993, gas will be exported from the Bruce field through a new 32-inch pipeline 5.8 km long which is now connected to the 32-inch Frigg UK line and on to St Fergus terminal in Scotland. The pipeline connection is through a subsea Wye component which has been tied into the Frigg UK line. The preparation works commenced in December 1991 and were completed in April 1992. The installation and isolation works were successfully performed in Summer 1992.
New Subsea Developments in a Mature Area: Planning for Access
Authors: King G. W. , Miller B. L. , Thomas P. V. 
Published: December 2007

ABSTRACT
In a mature development area such as the North Sea the addition of new small scale subsea developments can have a significant economic impact. Such fields are frequently developed using the infrastructure and services of an existing development. The paper considers a critical aspect of this pattern of developments: the need to include and maintain access for moored vessels within the development area with regard to the increased number of seabed flowlines.
The situations where access with a moored vessel are considered: at the new development; along the flowline route and at the platform facility. The problems of access are then addressed analytically and solutions presented for ‘design for clearance’ and ‘design for contact’ conditions. The technologies which could be used for these conditions are then discussed with regard to technical limitations and economic considerations.
The Greater Ekofisk Area: Addressing Drilling Fluid Challenges With Environmental Justifications
Authors: James R. W. , Helland Bjørn 
Published: December 2007

ABSTRACT
This paper discusses the drilling related complexities of the Greater Ekofisk basin which have demanded innovative shale stabilizing mud systems. The innovative mud systems discussed include "pseudo and synthetic" oil emulsion fluids; and cationic water based fluids. Phillips Petroleum Company Norway (PPCoN) has improved drilling fluids standards and drilling/wellbore performance with environment awareness.
The environmental evaluations of the innovative drilling fluids have involved a series of studies including Acute toxicity; Bio-degradability; and Bio-accumulation. In addition, marine seabed surveys have included studies to trace drilling fluids in the sea bottom sediments. The studies have revealed weaknesses in some test procedures. Through cooperation with external research laboratories, alternative test methods have been developed and evaluated.
The Application of High Flow Rate Well Testing Techniques on Precompleted Subsea Oil Wells
Authors: Jewell Stephen , Home Hugh 
Published: December 2007

Abstract
This paper describes the design and performance of a temporary surface welltesting system capable of processing up to 20,000 BOPD. The system was designed to meet the requirements for the post-completion testing of subsea oilwells on a North Sea development. The paper will be of interest to engineers wishing to achieve high flowrates during testing operations on semi-submersible drilling rigs.
Low-Energy, High-Reliability Platform for Gasfield Development
Authors: Fomiatti Stefano 
Published: December 2007

Abstract
A new approach in the definition of production & service units and in the operating management of platforms installed in the peripheral and marginal gas fields in the Adriatic Sea, is being developed in order to reduce investment & operating costs. The platform's new typology defined as BEAF (Low Energy - High Reliability), should reach the intervention and maintenance objective every 6 months by means of reduced production plants and highly reliable components.
Screening of WAG Injection Strategies for Heterogeneous Reservoirs
Authors: Surguchev L. M. , Korbøl Ragnhild , Haugen Sigurd , Krakstad O. S. 
Published: December 2007

Abstract
Microscopic oil displacement and sweep efficiency of waterflooding and continuous gas injection can be improved by water alternated gas (WAG) injection.
Reservoir and fluid properties are determining factors in screening WAG injection strategies. Evaluation of miscibility condition is an important step in the process design. Different correlations used for miscibility evaluation are compared on the Brent reservoir example. The effect of injection parameters on injectivity and recovery in the layers of a stratified reservoir is shown through the simulation results.
Methods improving WAG efficiency like non-stationary injection are discussed. Main parameters of cyclic injection with variation of flow directions are considered in relation with non-stationary WAG. Numerical modelling with respect to three phase effects showed the advantages of non-stationary WAG in a stratified reservoir.
Examining the Potential for Corrosion Inhibitor and Scale Inhibitor Compatibility in a Multifunctional Squeeze Strategy
Authors: Lawless T. A. , Bourne H. M. , Bolton J. R. 
Published: December 2007

Abstract
The molecular requirements and the fundamental physico-chemical mechanisms associated with inhibition of both scale and corrosion are reviewed establishing the general difficulties associated with the provision of single component, dual function agents. Molecular groups, steric effects, ion binding, conformational needs, ionisation and molecular weight are viewed theoretically to describe molecular demands on performance. An array of commercially available scale and corrosion inhibitors have been examined for their bulk and low concentration solution compatibility prior to the generation of detailed phase behaviour maps to elucidate realms of binary component coexistence. A compatible pair of inhibitor agents were selected for dynamic coreflood retention and release investigations, at elevated temperatures, to probe likely squeeze characteristics. Both single component and dual component formulations in adsorption only and precipitation modes were studied in detail. Desorption curves were successfully modelled with non-equilibrium models to help quantify operational mechanisms and identify future directions.
Efficient Iterative Linear Solution of Locally Refined Grids Using Algebraic Multilevel Approximate Factorizations
Authors: Wallis J. R. , Nolen J. S. 
Published: December 2007

Abstract
The objective of this work was to develop improved variations of the BEPS, FAC, and Sequential preconditioning methods used to solve composite grid linear systems. These methods are attractive since they use standard subgrid approximate factorizations in constructing the composite grid preconditioning. This paper describes two algebraic, multilevel grid coarsening procedures which allow efficient "black box" implementation of FAC and BEPS. The coarsening procedures are compared with regard to their effect upon convergence and computer efficiency. In addition all three methods may be modified to use variable step subgrid solutions to enhance convergence.
A Linear Equation Solver for Massively Parallel Computers
Authors: Li K-M. G. 
Published: December 2007

ABSTRACT
The latest generation of parallel supercomputers promises to deliver computational performance that is orders of magnitude higher than that of the sequential supercomputers. The major obstacle to using these supercomputers for reservoir simulations is the lack of software. Most existing reservoir simulators were developed to run on sequential computers and must be restructured to take advantage of these parallel systems.
The major bottleneck in the parallelization of a reservoir simulator is the solution of the linearized finite difference equation. Currently, the most robust techniques for solving large scale reservoir simulation problems are preconditioned conjugate gradient like methods. However, the more robust preconditioners such as nested factorization and ILU factorization are not suitable for parallel computers.
This paper describes a parallel linear equation solver that is suitable for large and small scale parallel computers. It is based on the preconditioned generalized conjugate residual method. The new preconditioner is a parallel variant of nested factorization. For the problems tested, the new solver is as robust as the more traditional solvers for sequential computers. Results are presented for large scale reservoir models running on the Cray C—90 and a massively parallel CM-2.
Multigrid Methods for Petroleum Reservoir Simulation on SIMD Machines
Authors: Dendy J. E. 
Published: December 2007

Abstract
In this paper we consider several multigrid methods on SIMD (single instruction, multiple data) architectures. The advantages and disadvantages of these methods are discussed. Actual timing data will be presented only at the meeting, since otherwise this paper would contain data five months old, rendering it obsolete in the current fast-moving world of parallel computation.
In a previous paper [DMRRS], a semicoarsening multigrid procedure was considered for solving three-dimensional problems that arise from pressure equations in reservoir simulation. In this procedure, semicoarsening was coupled with plane relaxation in order to accommodate anisotropies and heterogeneities. Subsequent work by Schaffer [S,SW] has improved the robustness of this procedure. Results of the implementation on the CM-200 of the twodimensional version of this procedure will be described, as will progress on the implementation on the CM-5 of the two-dimensional and three-dimensional versions.
Another possibility involves the use of Mulder's method as developed by Naik and Van Rosendale. [NR] In this method semicoarsened grids in both x and y (and z in three dimensions) are employed. The advantage is that general anisotropic problems require only point relaxation. This approach is compared to the above approach and shown to have better convergence factors but to be less efficient than the above method on machines like the CRAY-YMP. This method is being implemented on the CM-200 and CM-5 by using concurrent relaxation, interpolation, and restriction. This approach yields great parallelism but at the sacrifice of the splendid convergence factors.
A third possibility involves standard coarsening multigrid. This method seems less attractive than semicoarsening multigrid for SIMD machines, especially for three-dimensional problems.
A final possibility is the method referred to as BHT in [DIR]. This method uses standard coarsening but for every grid employs four coarse grids, thus keeping all the processors busy at every level. Busyness of processors is not innately virtuous, but the employment of supplemental coarse grids gives rise to a method which requires only point relaxation for simple anisotropic problems. It is the latter feature which makes the BHT method potentially attractive.
Under and Over Relaxation Techniques for Accelerating Nonlinear Domain Decomposition Methods
Authors: Nacul E. C. , Lett G. S. 
Published: December 2007

Abstract
Large reservoirs usually consist of several distinct drainage regions. Moreover, for simulation it may be desirable to use different grids in some regions. Such cases motivate a domain decomposition strategy at the reservoir level. The problem is split into several subproblems, corresponding to different drainage regions or grid types (or whatever other physical reasons there may be that motivate such a splitting). The subproblems can be solved separately, and by exchanging boundary information, the error at the interfaces can be reduced iteratively.
Such algorithms are attractive for parallel computation because of their coarse granularity and less communication, as compared to domain decomposition methods within the linear solver. A straightforward implementation of such methods, however, may converge slowly. The reason is the nonlinearity of the problem and the fact that in case of a linear problem, such methods would reduce to a simple block-Gauss-Seidel method, which is not an efficient solver. It is essential to apply acceleration techniques for such domain decomposition methods.
We present here two dynamic acceleration techniques for nonlinear domain decomposition methods. They use information from the previous time step, to calculate relaxation parameters. To test the robustness and efficiency of these techniques, three-phase black-oil examples with significant flow across subdomain boundaries and examples using locally refined grid have been computed. Results for our approach are compared with standard linear solvers. They show that with suitable acceleration techniques, a domain decomposition on the nonlinear (physical, reservoir) level is a feasible way to obtain coarse-grain parallelism.
The Treatment of Wells, Faults, and Other Singularities in a Black-Oil, Finite-Element Reservoir Simulator
Authors: Shaw D. C. 
Published: December 2007

Abstract
Several previous studies have applied finite-element techniques to reservoir simulation problems. However, these methods prove to be very complicated in the general case, and are not competitive with finite-differences in terms of equivalent speed for a given accuracy. In particular, most previous work has been on, at most, two-dimensional and two-phase problems. The full black-oil and three-dimensional case has been avoided because of its complexity.
By choosing only linear test functions and a first-order approximate integration scheme, the finite-element method simplifies enormously, yielding difference equations no more difficult than finite-differences. At the same time, the scheme has the improved convergence and grid-orientation insensitivity reported earlier in the literature. For equivalent accuracy, computing expense is therefore less than for finite-differences.
The method also allows a more accurate representation of singularities and discontinuities. They both introduce less truncation error with this method and can be located more precisely within a grid. Furthermore, they preserve the banded structure of the matrix problem, without the off-band connections typical of finite-differences.
Numerical results are presented demonstrating improved convergence, accuracy and the effects of locating a well more precisely within an element.
Full-Field Compositional Simulation of Reservoirs With Complex Phase Behavior
Authors: El-Mandouh M. S. , Bette Srinivas , Heinemann R. F. , Ogiamien E. B. , Bhatia S. K. 
Published: December 2007

SUMMARY
This paper describes the application of compositional reservoir simulation techniques in the management of large reservoirs. The equation-of-state compositional simulator was specifically enhanced to address several technical challenges, such as geologic heterogeneities including crossing faults and widely varying permeability, complex phase behavior of a near-critical fluid, and involved surface facilities operational constraints.
The application of the simulator to the Oso field in Nigeria is presented. The Oso field has two reservoirs. This field study reports on the major reservoir which contains a near-critical fluid and has a highly faulted structure. The fault model, in addition to accurately representing geologic faults and the associated flow across different layers, also reduced computational requirements considerably over the old conventional methods for fault representation. The reservoir fluid and its behavior near the critical region was characterized accurately using an 8-component, equation-of-state model.
The application of the model in the study of reservoir recovery under various production scenarios is discussed. The displacement mechanisms involved in the different depletion strategies are explained through a series of 1-dimensional simulations. This integrated approach in reservoir management enables us to determine an optimal development plan and surface facilities design parameters for the Oso reservoir.