bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nested Stochastic Simulations: A New Approach in Assessing Spatial Distribution of Carbonate Sedimentary Facies and Associated Diagenetic Overprints
Authors: Labourdette R. , Meyer A. , Sudrie M. , Walgenwitz F. , Javaux C. 
Published: December 2007

Abstract
A major challenge today is the development of carbonate reservoirs. They represent the most significant reservoir formation in the middle-east gulf region.
In carbonate reservoirs, heterogeneity is usually driven by both depositional and diagenetic patterns. The complex diagenetic history which prevails in these reservoirs influences the final static and dynamic reservoir properties. Dolomitisation is one of the most crucial diagenetic phases because of the way in which it constrains the permeability behaviour of the field. Detailed diagenetic research has shown that various genetic dolomite types exist, including evaporative, mixed evolved sea-water - freshwater and late thermobaric. Defining static rock-type can therefore be problematic due to the highly imbricate diagenetic phases and their various distributions and extensions. A further major difficulty is the spatial distribution of rock-types in reservoir models, each linked to different sedimentological and diagenetic processes and each with their own, but interdependent, geometrical characteristics.
In order to optimise the current production of reservoirs as well as future field development plans it is therefore necessary to understand the main diagenetic phases and develop approaches which effectively incorporate them into the static reservoir model.
This paper presents a synthetic modelling workflow applied to a large oolitic ramp derived from outcrop and field observations. This new approach is based on nested stochastic simulations, geologically-driven and derived from the relationships between dolomite type, stratigraphic position, palaeogeographic position, depositional facies, and proximity to fault/fracture zones. In addition to the initial depositional model, three diagenetic phases are modelled successively in order to restore the complex spatial relationship existing between diagenetic alterations.
The outcome of this modelling workflow, after a stage testing coherence with PC and Kr values and dynamic rock-typing definition, is fed into a dynamic simulator in order to assess the potential impact on field behaviour, production profiles and well productivity.
A Simulation Study of Performance Miscible Diplacement in El Gassi Field, Algeria
Authors: Tiab D. , Zhu T. , Merdaci C. , Bhangale A. Y. 
Published: December 2007

Abstract
El Gassi is a volatile oil field located in the Algerian desert. The field has produced about 62 MMSTB oil since 1959, through primary depletion. Due to the heterogenity of producing formation, the total recovery during 45 years is only about 11%. The implementation of water-flood project was avoided due to low achievable water injection rate. A miscible gas injection project is examined in this study. The purpose of gas injection is to maintain reservoir pressure and improve the microscopic efficiency to increase the overall recovery in the field. A laboratory study revealed that the miscibility could be achieved with a pressure of about 241.4 bars (i.e. 3500 psia), which is below the reservoir average pressure in El Gassi field. Typical reservoir heterogeneities encountered in El Gassi field were incorporated into the simulation model. The study includes history matching of past reservoir performance, investigation of different injection scenarios, optimization of injection well number, optimization of gas injection and oil production rates, and the benefit of drilling infill wells. Edge line gas injection appeared to be promising.
Two Phase Flow Properties of Brine-CO2 Systems in Carbonate Core: Influence of Wettability on Pc and kr
Authors: Chalbaud C. , Lombard J. -M. , Martin F. , Robin M. , Bertin H. , Egermann P. 
Published: December 2007

Abstract
The design of a CO2 injection project mainly depends on the results of reservoir models. Nevertheless, it is recognized that these models generally lack physico-chemical data. This issue becomes more important for storage options, such as deep saline aquifers, for which economically driven data collection and archiving have not been performed. Among these physico-chemical data, fluid/fluid and rock/fluid interactions have been long recognized to govern fluid distribution and behavior in the porous media. This paper focuses on rock/fluid interactions with the host formation, by means of the wettability, which is one of the controlling parameters of the remaining fluid saturations, capillary pressure and relative permeability; hence conditioning the performance of any CO2 operation.
The first part of this paper presents CO2 and N2 injection experiments in a carbonate core sample. Two different wettability conditions were investigated: water-wet and intermediate-wet. Thermodynamic conditions (pressure, temperature and water salinity) are representative of storage conditions and were the same for the entire core flooding experiments. Multirate experiments were conducted with in-situ saturation monitoring and enhanced interpretation workflow (heterogeneous approach) of the production curves in order to obtain relevant and complete sets of kr and Pc data. The second part is devoted to visualization experiments. CO2 injections were performed in glass micromodels, under the same conditions, in order to track the fluids distribution as a function of the thermodynamic and the wettability conditions.
Using this approach, we showed, on the one hand, that at the core (carbonate) and pore (micromodels) scale the CO2 does not wet the solid surface when the porous media is water-wet. On the other hand, if the porous media presents an intermediate wettability, the CO2 partially wets the substrate having significant effect on water mobility (krw). In all cases the results at the core scale were consistent with those at the pore scale.
Finally, we discuss the consequences of such CO2 wetting behavior in terms of fluids distribution in the porous media, injectivity level and seal efficiency of the caprock since all these mechanisms have a direct impact on CO2 storage capacity and sustainability of any prospect site.
A Model for Completion Selection for Multilateral and Multibranched Wells
Authors: Idiodemise E. J. , Dosunmu A. 
Published: December 2007

Abstract
With increasing demand for optimal production and reserve recovery, more fields are currently being developed using multilateral well technology. However, the success of a multilateral well depends strongly on the completion program, use of appropriate well architecture, optimal equipment selection and Junction selection. Well completion selection decisions rely on the use of various well decision criteria including reservoir consideration, equipment selection and technology, risk, as well as economic criteria. These criteria have been explained by [1] using flowcharts, a screen matrix and a risk model. In this study a new model was developed to aid completion selection for multilateral well applications. The method applied a modified Suglyama matrix for well selection, a junction screen matrix for junction selection, a sand completion selection model for sand control and other matrices developed in the course this study. The model considers different aspects of the well completion selection process. A user-friendly visual basic software was then developed to simplify the use of the models.
Using the software developed, two case studies were analyzed. The cases are reservoir with high mobility ratio [Case A] and another with low mobility ratio [Case B] Sensitivity analysis was then performed for the different reservoir parameters to determine their variation with well production. The advantage of this software is that it is cheap, proactive and aid in completion selection.
Prediction of the Viscosity of a Water-Base Mud Treated with Cassava Starch and Potash at Varying Temperatures Using Factorial Design
Authors: Okumo I. , Isehunwa S. O. 
Published: December 2007

Abstract
In order to monitor and control the properties of drilling fluids, measurements are routinely made at the surface. However, these surface measurements may not be representative of down-hole properties where the desired functions of hole cleaning and other related issues are critical to the success of the drilling operations. Consequently, it is important to make necessary adjustments of the fluid properties obtained at ambient conditions to give estimate of properties at high temperatures and pressures.
The principle and method of factorial design have been used to develop a model, which makes possible the prediction of drilling fluid viscosity at varying temperatures. Cassava starch and potassium carbonate were used as local additives in a water based bentonic drilling fluid after running a quality check. 23 full factorial design experiments which consider temperature, starch and potash as factor variables and viscosity as the response variable were conducted.
The main effects as well as the interaction effects were determined and examined. The results were analyzed and a predictive model was obtained. Viscosity values obtained using the model were compared with the experimental results and it was observed that the model has an accuracy of 93.6%.
This method makes possible the prediction of the viscosity of drilling fluids at varying temperatures, hence the treatment of mud systems can be determined ahead of time.
Convergence in Gas Pricing: What It Might Mean for Nigeria
Authors: Hunziker R. N. 
Published: December 2007

Abstract
The world's demand for gas is expected to increase at a faster rate than any other energy source; and, many traditional supply sources are approaching maturity. Many industry pundits call for an increasingly converging global market in natural gas. What are the possible implications and opportunities for Nigeria, which is well-endowed with natural gas resources and possesses a large latent energy demand of its own?
The paper illustrates some of the signposts of the trends behind growth in natural gas market convergence. Nigeria is well-known for its gas resources; so, the paper will move-on from a review of the commercial frameworks to some of the implications and opportunities for Nigeria. Finally, the paper concludes with references to the Theme for NAICE 2007: "Optimization of Oil & Gas Potentials."
Calibration of the Elemental Capture Spectroscopy Tool Using the Niger Delta Formation
Authors: James Egbe Samuel , Omole O. , Diedjomahor Jacob , Crowe John 
Published: December 2007

Abstract
The Elemental Capture Spectroscopy tool (ECS) is calibrated for improved formation evaluation in "Hot sands ’ of the Niger Delta. This is done by combining the tools signal (Capture gamma ray spectrum) obtained from well # XD1 in the Niger Delta and concentrations of elements derived from the analysis of a core sample obtained from well # XD1, to produce calibration equations for the various elements measured by the tool.
The Window's method of spectral analysis was used in this study rather than the well known Yield's method. This is because the Window's method has great precision over the Yield's method at the tool's logging speed (1800ft/hr), and spectral energy resolution at operating temperatures in the borehole.
The calibration equations were validated by using spectral data obtained from a given depth in well #XD1 to predict the known elemental concentrations at that given depth. Predicted average elemental concentrations correlated very well with known average elemental concentrations.
Maximizing the Potential of Decline Curve Analysis
Authors: Aitokhuehi I. 
Published: December 2007

Abstract
The data most collected within the oil industry is the rate-time data. This data is analyzed with decline curve to primarily determine well/reservoir remaining reserves. However, rate-time data, which is a form of extended well testing, can also be used to estimate other reservoir parameters such as permeability and/or relative permeability curve.
In this paper, we utilized Masoner's decline derivation to show that estimates of the relative permeability curve can be obtained from a well under voidage rate control in a solution gas drive system. For a well under pressure control in a solution gas drive reservoir, however, we show that the decline is exponential and obtain an expression for the permeability. The results were applied to data from solution gas drive simulation models and are presented. Application to field data is also presented.
Analytical Method for Diagnosing and Predicting Pressure Response with Injection in Waterflood Reservoirs using Net Voidage Curve.
Authors: Okoro I. C. , Okojie S. E. , Umurhohwo J. O. 
Published: December 2007

Abstract
A critical component of waterflood management is the ability to proactively determine the impact of injection rates on the reservoir pressure and the capacity to diagnose injection anomalies. The most reliable means of doing this is through the use of numerical models. However, these models may be expensive to build and difficult to maintain. Therefore, a simpler and less expensive method to forecast the impact of injection rates on reservoir pressures, under various injection and production scenarios, is of immense benefit.
The method presented in this paper was developed and used by a team of Engineers managing the Meren field waterflood project to diagnose pressure response anomalies and provide estimates of injection targets to achieve any expected pressure response for the project reservoirs without the use of numerical models. It uses the slopes of the cumulative net voidage curve and the measured change in pressure response to define reservoir specific relationships between injection and pressure response. Case study on application of method for diagnosing pressure response anomalies was presented. Also, example pressure prediction calculations were performed on a project reservoir. These examples clearly establish the method as a valid tool for the early identification of injection anomalies and prediction of reservoir pressure changes. Comparison of actual pressure survey data and those predicted with the analytical model indicated that both were on the same trend.
Quantitative Mineralogy of Reservoir Rocks Using Fourier Transform Infrared Spectroscopy
Authors: Ballard Bryce D. 
Published: December 2007

Abstract
An inversion scheme was modified to quantitatively determine the mineralogy of reservoir rock samples using transmission Fourier transform infrared spectroscopy (FTIR). This inversion scheme adds apatite and aragonite to the previous inversion and is now capable of recognizing 16 minerals. The other minerals include quartz, calcite, dolomite, illite, smectite, kaolinite, chlorite, pyrite, orthoclase, oligoclase, mixed clays, albite, anhydrite, and siderite. The inversion predicts the mineral concentrations with an average error of +/- 1.1 wt % and within a standard deviation of +/- 2.1 wt %. It also found that 97 % of mineral concentrations are accurately predicted within +/- 5 wt %. These prediction errors are similar to published values for error associated with X-ray diffraction (XRD) which has become the industry standard for mineralogy analysis. The addition of apatite allows rapid and accurate quantification of mineralogy in gas shale reservoirs which have become a major play in U.S. natural gas exploration.
Heavy Fraction C7+ Characterization for PR-EOS
Authors: Sancet Gastón Fondevila 
Published: December 2007

Abstract
A compositional simulator uses an Equation of State (EOS) to predict the pressure-volume-temperature (PVT) behavior of gas and crude oil fluids, which are very complex hydrocarbon mixtures.
In a hydrocarbon mixture, the critical properties (critical pressure "Pc", critical temperature "Tc" and accentric factor "ω") must be given for each component. These properties are well known for pure compounds (like methane, ethane, etc.), but nearly all naturally occurring gas and crude oil fluids contain some heavy fractions that are not well defined. These heavy fractions are lumped and called the "plus-fraction" (C7+). There arises the need of adequately characterizing these undefined plus fractions in terms of their critical properties.
This work presents a correlation for the critical properties of the plus-fraction C7+ needed in the characterization of crude oil fluid samples for a compositional simulator using Peng-Robinson's1 EOS. The correlation is a function of the fraction's molecular weight (MW).
Twenty (20) PVT laboratory tests made in black oil fluid samples taken from fields of the Neuquén Basin (Argentina) were utilized for the adjustment of the bubble point (Pb), gas-oil ratio (GOR), constant composition expansion pressure-volume relation (PV) and differential expansion curves (Rs, Bo and ρo) of the compositional simulator.
A comparative study was performed against the Riazi-Daubert's2 correlation. The correlation here presented gives better results than those of Riazi-Daubert's correlation and also gives excellent liquid density predictions when there are high MW hydrocarbons present in the fluid.
Streamline-Based Reservoir Model Calibration to Three-Phase Production Data
Authors: Oyerinde Adedayo 
Published: December 2007

Abstract
Streamline-based assisted and automatic history matching techniques have shown great potential in reconciling high resolution geologic models to production data. However, a major drawback of these approaches has been incompressibility or slight compressibility assumptions that have limited applications to two-phase water-oil displacements only. Recent generalization of streamline models to compressible flow has greatly expanded the scope and applicability of streamline-based history matching, in particular for three phase flow. In our previous work, we calibrated geologic models to production data using the generalized travel time inversion (GTTI) technique. For field applications, however, the highly non-monotonic profile of the gas/oil ratio data often presents a challenge to this technique. In this work we present a transformation of the field production data that makes it more amenable to GTTI. Further, we generalize the approach to incorporate bottom-hole flowing pressure during three-phase history matching. We examine the practical feasibility of the method using a field application. The field case is a highly faulted, west-African reservoir with an underlying aquifer. The reservoir is produced under depletion with three producers, and over thirty years of production history. The simulation model has several PVT and SCAL regions and over a hundred thousand cells. The GTTI is shown to be robust because of its quasi-linear properties as demonstrated by the water-cut and GOR match for a period of 30 years of production history.
Water Saturation Evaluation in Shaly Sand Reservoirs Using Advanced X-ray Diffraction and Cation Exchange Capacity Measurements
Authors: Ugbo Justin 
Published: December 2007

ABSTRACT
Interpretation problems are commonly associated with calculating water saturation in non-homogenous shaly sand reservoirs. Recent studies on the electrical anisotropy of shaly sands have shown that the level of our understanding our ability to correctly and accurately evaluate complex shaly sand reservoirs can be greatly improved.
The model ("Total Expansible Clay Model") developed in this work is similar in form to the recent shaly sand Dual Water Model, except that the clay effect have been defined by a volume-conductivity transform rather than the usual volume-porosity transform.
The model is experiment-based and designed to quantify the effects of the mineralogical and electrical properties of clay minerals on well log signatures.
The Total Expansible Clay Model evaluates these effects via direct measurement of independent mineralogy and cation exchange capacity of the clay minerals within the reservoir sands.
The model integrates the following as an effective basis for characterizing shaly sand reservoirs:
Rietveld based siroquant assay for quantitative X-ray diffraction (XRD) used in determining mineral percentages from standard XRD trace patterns, Cation exchange capacity (CEC) used to determine the quantity of cations involved in the exchange at the shale-water interface, Porosity, permeability, density and resistivity measurements,
Overall, the correlations drawn from this model yield improved results for total water saturation (especially in low porosity and highly shaly formations), which appear consistent with those calculated earlier using well known water saturation models (Dual Water and Juhasz). A total of 23 core plugs from two wells in the Cliff Head Field, Perth Basin, were analyzed for this study.
Deepwater Driven Advancements in Well Control Equipment and Systems
Authors: Vigeant Shawn P. 
Published: December 2007

Abstract
The recent surge of deepwater drilling activity throughout the world, and in particular the US Gulf of Mexico has prompted oil companies, drilling contractors and equipment manufacturers alike, to develop and implement a wide variety of technologically advanced systems designed to overcome the adversities associated with the harsh environment of today's extreme water depths. In particular well control equipment and related systems have undergone the greatest transformations and made the most significant technological gains.
Development and Application of an Underbalanced Drilling Simulator
Authors: Bijleveld A.F. , Koper M. , Saponja J. 
Published: December 2007

Abstract
A part of the planning of underbalanced operations is to estimate drilling and production related parameters. Wellbore pressure and fluid phase velocity profiles, hydrocarbon production management mechanisms and injection gas requirements are necessary for designing underbalanced drilled wells. A steady state underbalanced drilling software tool has been developed by Shell to assist their well engineers in planning and executing underbalanced operations. The simulator has been validated and its accuracy proven with field data comparisons. The accuracy was within the range of the intended area of application and has indicated less than 10% difference in measured wellbore pressures. The objective of the software development is to release the simulator to the industry. Concurrently the model will be developed further and its accuracy improved. A concern at the moment, is the limited number of wells drilled underbalanced with sufficient data gathered to allow extensive simulator comparison.
To obtain an overview of capabilities and applicability of presently on the market available simulators, a thorough comparison between models is recommended.
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