bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and Testing of an Expandable Casing Patch System
Authors: Braddick B. O. , Jordan G. D. , Baker S. F. , Stulberg M. A. 
Published: December 2007

Abstract
Since the early years of cased hole completions, casing patches of various designs have been used to seal off annular leaks down hole. Casing patches of prior art would typically restrict the operator the ability to run large diameter tools below the patch leaving the well bore with a less than desirable tubing size for completions. Also, current designs of casing patches that are available are typically weaker with respect to the pressure integrity of the patch itself.
Recent interest along with the technological advances of expandable tubulars have led to a new design of casing patch that permits a more desirable size of completion string. In addition to this, it was also realized in the design and testing phase, that a patch could be developed with pressure integrity that meet or exceed the tubing and/or casing string in which it is set.
This paper will focus on the unique features of this high pressure, large thru bore expandable casing patch system from the initial customer contact, to the trials and tribulations of the design and the research and development testing process. Actual field use of the tool including applications and sizes will also be briefly discussed, as the patch system has been deployed in wells ranging from the Texas panhandle to Wyoming1.
In conclusion, this paper will discuss how the developmental process of this particular tool has led the manufacturer to the design of several other new tools for various down hole applications.
Application of a New Mechanistic Parachor Model to Predict Dynamic Gas-Oil Miscibility in Reservoir Crude Oil-Solvent Systems
Authors: Ayirala Subhash C. , Rao Dandina N. 
Published: December 2007

Abstract
Interfacial tension (IFT), being an important thermodynamic property of the interface between two fluid phases in contact, can be used for phase behavior characterization, interpretation of fluid phase equilibria and miscibility. In order to examine these multitudes of roles played by interfacial tension, gas-oil IFT measurements were carried out for Rainbow Keg River (RKR) and Terra Nova reservoir fluids at elevated pressures and temperatures [1, 2]. A computerized drop shape analysis technique was used to fit the actual drop profiles of pendent oil drops with the iterative solution of the Laplace capillary equation for gas-oil IFT determination. These measurements have enabled the development of a new gas-oil miscibility determination technique called the vanishing interfacial tension (VIT) technique [1, 2].
In this paper, we propose a mass transfer enhanced mechanistic Parachor model to predict the gas-oil IFT at reservoir conditions and to identify the governing mechanism of mass transfer to attain fluid phase equilibria. The proposed model incorporates the ratio of diffusivities between the fluid phases raised to an exponent to account for mass transfer effects. The proposed model resulted in good IFT predictions as well as indicating that vaporization of light hydrocarbon components from crude oil to gas phase is the governing mass transfer mechanism for the attainment of fluid phase equilibria in these two reservoir fluids. The sensitivity studies on model results indicate that the provision of a single experimental IFT measurement is sufficient for accurate IFT predictions at other conditions from the model. Regression equation has been developed relating the exponent in the mechanistic model to the normalized solute compositions present in either of the two fluid phases for RKR and Terra Nova reservoir fluids. This regression equation, if generalized, using more reservoir crude oil-solvent systems, can be used for a-priori prediction of exponent in the mechanistic model by simply knowing the reservoir fluid compositions, without the need for experimental measurements. The use of diffusion coefficients in the mechanistic model indicates dynamic nature of IFT, thus enabling the use of model predictions to determine dynamic gas-oil miscibility in gas injection EOR projects.
Steady-State Propagation of In-situ Combustion Fronts with Sequential Reactions
Authors: Akkutlu I. Yucel , Yortsos Yannis C. 
Published: December 2007

Summary
The sustained propagation of a combustion front is necessary for the improved recovery of oil during an in situ combustion process. In situ combustion involves the added complexity of chemical reactions. In this paper, combustion will involve two sequential oxidation reactions. High-temperature oxidation represents proper combustion, its fuel generated by the preceding low-temperature oxidation. The interaction between the two reactions in the presence of reservoir heat losses and their overall influence on front propagation are investigated using a perturbation, analytical approach, based on the assumption of large activation energies. The places where the reactions occur are treated as spatial discontinuities for heat and mass fluxes, across which appropriate jump conditions are developed. Under certain conditions, the two reaction regions are coupled and travel coherently with the same velocity. The corresponding parameter space is delineated. The resulting common velocity is investigated as a function of the various parameters, including heat losses. The work finds application to our understanding of in-situ combustion processes and their application to oil and bitumen recovery.
Drilling Further with Water-Based Fluids—Selecting the Right Lubricant
Authors: Knox D. , Jiang P. 
Published: December 2007

Abstract
This paper summarises the results of extensive laboratory work carried out in recent years to determine the performance of a number of experimental and commercially available lubricants for reservoir applications. The laboratory work included a series of tests to determine formation damage potential in both completion brines and low-solids, water-based reservoir drilling fluids, as well as reduction in friction coefficient.
The testing to evaluate formation damage potential included brine miscibility, greasing and emulsion formation potential, as well as return permeability testing on outcrop sandstone.
Planning EOR Projects
Authors: Hite J. Roger , Avasthi S. M. (Sam) , Bondor Paul L. 
Published: December 2007

Abstract
High oil prices and concerns about future oil supply are leading to a renewed emphasis on Enhanced Oil Recovery (EOR), a group of technologies which can significantly increase the recovery factor of oil reservoirs. Some of these EOR technologies are currently producing substantial incremental oil; others have not yet made a commercial impact. As all EOR processes are reservoir- and reservoir fluid-specific, it is necessary to identify the appropriate EOR technology for use in a reservoir, design the project to achieve the required economic incremental recovery, and manage the project to meet or exceed expectations. This paper discusses how to plan, design and manage an EOR project, proceeding from process selection through geologic analysis and modeling, project economics, project design, pilot testing (when and if required), and project implementation and surveillance. In each stage, key risks are identified, and actions to minimize those risks are given.
On the Inverse Problem of the Estimation of Multiphase Flow Functions
Authors: Nieto V. L. , Savioli G. B. , Bidner M. S. 
Published: December 2007

Abstract
An inverse method is described for simultaneously obtaining relative permeability and capillary pressure curves from measurements taken during an unsteady state oil-water flow experiment at the laboratory. This inverse method algorithm has four basic components: 1) an IMPES finite-difference numerical simulator of the flow through the core; 2) functional representations-power law models or piece-wise linear splines-of relative permeability and capillary pressure curves in terms of a set of adjustable parameters found by minimizing an objective function; 3) the objective function, formed by the sum of the square of the differences between the experimentally measured and the numerically simulated data; 4) the Quasi-Newton Approximation for the Least-Squares Problem (QNA) technique to minimize that objective function. The method is tested with synthetic and experimental data.
The QNA optimization technique performs better than other methods of the Newton type. Besides, it is simpler to implement than the genetic and optimal control algorithms. The accuracy of the relative permeability and capillary pressure estimations depends on the objective function definition. That definition, in turn, depends of the different kinds of available measurements (flow rates, pressure drop, saturation profiles at different times) and of the functional representations (power functions or piece-wise linear splines) of relative permeability and capillary pressure curves. Automatic history matching of a laboratory two-phase displacement to obtain relative permeabilities and capillary pressure is a classical ill-posed inverse problem. The solution of the lack of uniqueness and convergence of the method cannot be warranted for all cases by the introduction of more data (i.e. saturation profiles), more refined functional representations (piece-wise linear splines) or better optimization techniques.
The Use of Tracers to Characterize Highly Heterogeneous Fluvial Reservoirs: Field Results
Authors: Badessich M. F. , Swinnen I. , Somaruga C. 
Published: December 2007

Proposal
Before the start of an enhanced oil recovery project it is important to adequately describe the architecture of sand bodies, preferential flow directions and permeability barriers.
As a consequence of project implementation operating costs tend to increase so in order to guarantee the economic success of the venture, reservoir surveillance plays a major role. This is mandatory in highly heterogeneous reservoirs where it becomes strictly necessary to identify and adjust any deviation from the anticipated response to injection.
This paper presents the results of the use of chemical and radioactive tracers in Grupo Neuquen reservoir, Loma Alta Sur field, Argentina. The objectives have been to improve the dynamic description of the reservoir previous to the injection of costly polymers and surfactants and to optimise the secondary flood by increasing volumetric sweep efficiency.
This field has been in production since 1990. Water injection started in 1993 and due to field observations of poor reservoir connectivity an intensive programme of tracers was recommended. Three injectors were inoculated, one of them with ammonium thiocyanate and the rest with tritiated water. Fifteen producers were monitored throughout twelve months.
Field data is presented in this report. It shows that hydraulic connectivity is higher than expected although fluid migration among wells is highly variable depending on reservoir transmissibility and channel orientation. For wells separated only 300 feet arrival times of few hours were reported. From these observations it was concluded that many sand bodies still produce under primary recovery. Sands with better transmissibility and continuity are constantly recycling injected water contributing little to reduce oil saturation. As a consequence a full field reservoir description in a sand by sand basis was initiated before the implementation of an EOR process.
New Analytical Pressure-Transient Models to Detect and Characterize Reservoirs With Multiple Fracture Systems
Authors: Dreier Jürgen , Ozkan Erdal , Kazemi Hossein 
Published: December 2007

Abstract
This paper presents two new pressure-transient models for naturally fractured reservoirs. The analytical models consider flow in a quadruple-porosity system that consists of a triple-fracture network with a single-matrix system. The models are used to investigate the pressure-transient characteristics of quadruple-porosity systems. They can also be used to detect, characterize, and simulate naturally fractured reservoirs with quadruple-porosity characteristics. It is shown that the fracture interconnectivity can be determined from pressure-transient tests if the combined fracture storativity is sufficiently large and the matrix contribution can be unambiguously isolated. Regression analysis of pressure-transient tests in naturally fractured reservoir with quadruple-porosity behavior is also discussed. It is demonstrated that the standard regression techniques are very sensitive to the scatter of the pressure vs. time data.
Successful Field Surveillance Using Portable Multi-Phase Flow Meter in a High Gas-Volume Fraction and High Water-Cut Application in East Kalimantan, Indonesia
Authors: Wangsa S. , Latief R. , Kaura J. , Finley D. , Ogilvie A. 
Published: December 2007

AbstractTotal Indonesia had been finding it increasingly more difficult to obtain direct measurement of produced oil from some of their remotely located fields. The production wells that needed testing were in a mature field in a swamp location and had high water-cuts (WC) and extremely high gas-volume fractions (GVF). The WC and GVFs in these fields range from 80 to 100% and 90 to 100%, respectively. Moreover, most of the wells have low potential and are very sensitive to back-pressure. All these characteristics as well as their logistics made accurate measurement of production from the wells in this area extremely challenging. As a result, the time interval between the well tests was ever increasing (more than one month).In order to achieve more frequent performance data, and thus, enable more effective work-over decisions, the suggestion was made to evaluate use of a portable multi-phase flow meter (MPFM) to resolve the measurement problems.The initial well tests yielded MPFM total liquid flow-rate readings that were ±30% of the test separator readings; the MPFM gas rates were ±25% of the separator reading. The operator's requirement was for the MPFM to be within ±10% of the test separator readings. Since these disparities were attributed to the extremely high GVFs that had been encountered on these wells, modifications to the present MPFM system were needed toReduce the GVF going through the meter Reduce the uncertainty of the meter measurements Improve the accuracy of the meter Increase the meter operating envelope.Subsequently, a gas knock-out (GKO) vessel was designed and constructed to address the above needs. The GKO vessel was designed within a predetermined set of constraints so as to achieve the desired results.The GKO vessel was installed immediately upstream of the multiphase meter. After incorporating the GKO vessel with the MPFM, the new "hybrid" system was used to test the same wells that had been tested earlier. The results using the MPFM and the GKO vessel yielded liquid rates and gas rates that were within ±10% of the test separator.
Why so Many Different Types of Wells on Njord?
Authors: Talukdar Saifullah , Brusdal Lill Harriet 
Published: December 2007

Abstract
The Njord Field is one of the most complex reservoirs in the Norwegian North Sea due to a large number of faults. Seismic quality in the heavily faulted areas is poor making seismic interpretation difficult. Typically the uncertainty in top structure is in the order of 10-100 m.
The well design criteria on Njord are dependent on the structural uncertainty and the availability of new technology. Njord started with relatively simple single-bore horizontal wells. This design was not suitable in the intensely faulted areas. High amplitude U-, S- and W-shaped wells have been effective to penetrate all reservoir units in uncertain areas, to minimize the risk of hole-instability and to drain oil from multiple fault compartments.
The need for placing a well in the best reservoir interval, to penetrate longer reservoir section and to drain oil from sparsely located undrained compartments led to drill a tree-branched well in the recent days. A new active visualization assisted geo-steering technology coupled with biostratigraphy has been tremendously successful to steer the well path in the most complicated area. Another well has been drilled in another heavily faulted area where the pressure depletion in some of the compartments was in excess of 300 bar.
The drive for a cheaper way of drilling sparsely located relatively smaller undrained pockets led to initiate a new campaign to find and drill low cost infill targets using the Through Tubing Rotary Drilling technology. Intensive research and development activities have been undertaken to resolve outstanding issues, such as, protection of X-mas tree and down hole safety valve, risk for mud loss and differential sticking, zone isolation by swell packers, etc.
This paper summarizes the reasons for adopting so many different well types, and a comprehensive description on their planning, execution, challenges, successes and failures.
Effect of Ultrasonic Waves on the Capillary-Imbibition Recovery of Oil
Authors: Hamida T. , Babadagli T. 
Published: December 2007

AbstractAlthough the effects of ultrasonic irradiation on multiphase flow through porous media has been studied in the past few decades, the physics of the acoustic interaction between fluid and rock is not yet well understood. Insight into the physical principles governing the mobilization of oil by ultrasonic waves is vital for developing novel techniques of oil extraction.Various mechanisms may be responsible for enhancing the flow of oil through porous media in the presence of an acoustic field. Capillary related mechanisms are peristaltic transport due to mechanical deformation of the pore walls, reduction of capillary forces due to the destruction of surface films generated across pore boundaries, coalescence of oil drops due to Bjerknes forces, oscillation and excitation of capillary trapped oil drops, forces generated by cavitating bubbles, and sonocapillary effects.This paper aims at identifying and analyzing the influence of high-frequency, high-intensity ultrasonic radiation on capillary imbibition. Laboratory experiments were performed using cylindrical Berea sandstone and Indiana limestone samples with all sides (co-current imbibition) and only one side (counter-current imbibition) open to flow contacting with the aqueous phase. The oil saturated cores were placed in an ultrasonic bath, and brought into contact with the aqueous phase. The recovery rate due to capillary imbibition was monitored against time.Air-water, mineral oil-brine, mineral oil-surfactant solution and mineral oil-polymer solution experiments were run each exploring a separate physical process governing acoustic stimulation. Water-air imbibition tests isolate the effect of ultrasound on wettability and capillarity, while oil-brine imbibition experiments help understand the ultrasonic effect on viscosity and interfacial interaction among oil, rock and aqueous phase. We observed a substantial increase in final recovery (up to 15%), and a slight increase in recovery rate when ultrasonic waves were applied. A modified form of an exponential model was employed to fit the recovery curves to clarify the factors causing an incremental recovery by ultrasonic waves for different fluid pairs and rock types.
Abandonment of the NW Hutton Platform Wells
Authors: Kirby Steve , Skelly Garry , Campbell Ken 
Published: December 2007

Abstract
This paper discusses the systematic approach adopted by BP Exploration to achieve its objective of safely recovering the tubing, casing and conductors from the wells on a major North Sea Platform. An integrated team, comprising oil company engineers and key service company personnel developed processes and procedures to reach the objective. The project applied conventional and non-conventional technology to address the issues. This approach facilitated the timely and cost effective recovery of 40 wells in a safe and environmentally friendly manner and in achieving world-class performance.
Fracture Closure Stress (FCS) and Lost Returns Practices
Authors: Dupriest Fred E. 
Published: December 2007

Abstract
In the mid 1990's the operator's lost returns mitigation practices were modified to align with a simple, but robust, rock mechanics concept that described the manner in which LCM and other products work. The model holds that regardless of the type of treatment used, integrity is increased by widening the fracture to increase its closing stress. Field practices have been changed to enhance a variety of mechanisms that may play a role in this process. Depending on the product, these mechanisms may include development of an immobile mass, deposition of solids in layers, development of viscous resistance, and the deposition of adhesive solids. The paper presents the development of the rock mechanics perspective, the resulting Fracture Closure Stress (FCS) Practices, a treatment selection guide, worldwide results, and discussion of the key factors that continue to limit performance in some situations.
Achieving Long-Term Isolation for Thin Gas Zones in the Adriatic Sea Region
Authors: Moroni N. , Vallorani F. , Johnson C. , Perez D. , Bilic J. 
Published: December 2007

AbstractThis paper describes the application of a flexible cement system to isolate pay zones, spaced 1 m apart, in the Barbara gas field in the Adriatic Sea, off the coast of Italy. This field presents several challenges to achieving long-term zonal isolation—crossflow between pressured zones, changing mud weights, and a high-pressure cold-fluid injection fracture treatment. One or more of these conditions may contribute to a loss of isolation; hence, there is a need for an effective sealant material that can handle these challenges. Conventional cement systems have been unable to address zonal isolation at such a scale.In view of these various challenges, the team in charge of cementing these wells redesigned the cement program to mitigate the risks in the field. The main objective was to minimize the Young's modulus (maximize flexibility) and maximize the compressive strength of the set cement. Thus, an extensive program was carried out to measure the mechanical properties of the set cement. The new cement program used a flexible, expandable slurry system that isolated five zones behind 7-in. casing in the Barbara gas field. A cement-bond log evaluation confirmed isolation of the pay zone. No losses were observed during cement placement across the low-fracture-gradient formations. The new slurry system brought substantial value to the operation by enabling use of 7-in. casing as the production casing. It also eliminated any interzonal pressure communication between formations and the need for an additional 5-in. liner, which saved rig time and rig costs.