bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Method for Measuring Solvent Diffusivity in Heavy Oil by Dynamic Pendant Drop Shape Analysis (DPDSA)
Authors: Yang Chaodong , Gu Yongan 
Published: December 2007

Abstract
This paper presents a new experimental method and its computational scheme for measuring the diffusion coefficient of solvent in heavy oil under the practical reservoir conditions by dynamic pendant drop shape analysis (DPDSA). In the experiment, a see-through windowed high-pressure cell is filled with the test solvent at desired pressure and temperature. Then a heavy oil sample is introduced slowly through a syringe delivery system to form a pendant drop inside the pressure cell. The subsequent diffusion process of solvent into the pendant oil drop causes its shape and volume to change until an equilibrium state is reached. The sequential digital images of the dynamic pendant drop are acquired and digitized by applying computer-aided digital image processing techniques. Physically, variations of the shape and volume of the pendant drop are attributed to the interfacial tension reduction and the well-known oil swelling effect as solvent gradually dissolves into heavy oil. Theoretically, the dynamic pendant drop profile is governed by the Laplace equation of capillarity and the molecular diffusion process of solvent into the pendant oil drop is described by the mass diffusion equation. An objective function is constructed to express the discrepancy between the experimentally observed and the numerically predicted profiles of the dynamic pendant drop. The solvent diffusivity in heavy oil and the mass-transfer Biot number are used as adjustable parameters and thus determined once the minimum objective function is achieved. This novel experimental technique is tested to measure diffusivities of carbon dioxide in a brine sample and carbon dioxide in a heavy oil sample, respectively. It should be noted that, with the present technique, a single diffusivity measurement can be completed within an hour and only a small amount of oil sample is required. The interface mass-transfer coefficient at the solvent-heavy oil interface can also be determined. In particular, this new technique allows the measurement of solvent diffusivity in an oil sample at constant pre-specified high pressure and temperature. Therefore, it is especially suitable for studying the mass transfer process of injected solvent into heavy oil during solvent-based post-cold heavy oil production (CHOP).
Using Cross Dipole Sonic Anistropy Data to Improve Reservoir Understanding in the Southern/Marine Areas of Mexico
Authors: Aquila Fredy Jimenez , Carmen Ciudad del , Barajas Jose Sanchez , Mesa Harold , Herrera Ricardo Rodriguez , Kessler Calvin 
Published: December 2007

Abstract
Crossed dipole sonic logging data has been used to improve reservoir understanding in the Southern/Marine areas of Mexico. The anisotropy analysis of the in-line and cross-line dipole waveform data provides the fast and slow shear wave travel time data and their corresponding orientation. These slowness values provide the input to a model that calculates the minimum and maximum principal stresses and the far-field stress orientation. The far-field stress orientation and stress anisotropy combined with 3D hydraulic fracture modeling is used to optimize the stimulation treatment design. The far-field stress information is also used for optimizing the perforated interval and orientation of the perforations.
Natural fractures provide many challenges for drilling, zonal isolation, and production enhancement. The detection and orientation of natural fractures is a needed key for reservoir management, and can be determined from the cross dipole anisotropy analysis. Inflow analysis from production logs has verified that the fractures identified by anisotropy analysis are open and are a major source of production in the Cretaceous section in the Marine area and Cretaceous/Jurassic in the Southern area. Mapping of the fracture orientation obtained from the sonic anisotropy analysis is used for well planning. Crossed dipole log examples in carbonate formations in Mexico will be used to illustrate how reservoir understanding can be improved with the use of this interpretation process.
Correlations of Shear vs. Compressional in Shaly Sands and Application to Quicklook Hydrocarbon Detection
Authors: Chardac O. , Brie A. , Chouker A. C. 
Published: December 2007

Abstract
Since the introduction of the dipole shear sonic measurements a large number of compressional and shear data sets have been acquired, especially in shaly sands. Correlations between these measurements are now well established and used routinely. The Castagna mudrock and sandstone lines on the Vp and Vs crossplot are popular among geophysicists while trends of Vp/Vs versus Δt proposed by Brie et al. (1995) are popular among petrophysicists. As expected, a comparison of these correlations shows that they are quite similar in saturated and dry conditions. However, the Vp/Vs trends can simulate different pore fluid types or saturation conditions because the fluid effect is accounted for through the Gassmann equation.
Using published correlations for adiabatic elastic moduli with temperature and pressure, we have generated slowness charts for water solutions and hydrocarbons and used them to refine the Vp/Vs trends. In particular we generated different trends for sands impregnated with fresh water, salt-saturated water and live oil. We show that the Vp/Vs trend for live oil is quite distinct from that in water.
An application of these correlations is to convert shear to compressional. As shear slowness is little sensitive to fluid type, the obtained compressional slowness, Δtwet, simulates water-filled shaly sands. A comparison of Δtwet with measured Δt provides a quicklook indicator of hydrocarbons. Various examples are presented and discussed. We show that all correlations give good results in sands with porosity larger than 20%. Between 10 and 20% porosity, correlations must be adjusted to obtain reliable results. Below 10% porosity, the technique becomes unusable.
The Δtwet estimate has other interesting applications in the domain of rock mechanics and stress evaluation because it is unaffected by fluid content. An example shows how the technique was applied to improve hydraulic-fracture design.
Determination of Primary and Secondary Porosity in Carbonate Formations Using Acoustic Data
Authors: Kazatchenko Elena , Markov Mikhail , Mousatov Aleksandr 
Published: December 2007

Abstract
A technique for quantitative estimation of crack or vug porosity using acoustic well-log data is proposed. The estimation is based on a double-porosity rock model that consists of a solid matrix with primary porosity and inclusions which represent the secondary pore system. We applied the method of effective medium approximation (EMA) to calculate P- and S-wave velocities in the double-porosity formations. This method allows modeling multicomponent systems composed by grains of different mineral components, primary pores and secondary inclusions. All these components are approximated by spheroids with different aspect ratios.
The technique includes two steps. At the first step the matrix P- and S-wave velocities as functions of the primary porosity are calculated. For this procedure two groups of parameters are required: 1 - solid-skeleton elastic moduli that are defined by laboratory measurements or calculated using formation mineralogical composition; 2 - aspect ratios for grains and primary pores. We determined these aspect ratios by the inversion of the published regression equations for P- and S-wave velocities to the microstructure parameters.
At the second step, using the obtained previously matrix parameters, the value and aspect ratio of secondary pores are determined by the joint inversion of P- and S-velocities (minimizing the difference between the experimental data and velocities predicted for the double-porosity model). The obtained aspect ratio indicates the type of secondary-pore system (cracks or vugs).
Examples of secondary-porosity determination using acoustic core and well log data are presented.
Completion Optimization in the Wamsutter Field, SW Wyoming
Authors: Heidt J. H. , Harting T. A. , Glover M. D. , Rowe W. , Adegbola K. A. , Rucker L. R. 
Published: December 2007

Abstract
This paper describes the successful application of a rigorous optimization process to new well completions in the Wamsutter area of SW Wyoming. High well costs and relatively low netback product prices require that all new well completions be rigorously optimized for maximum value. Excellence in stimulation design, execution, and evaluation is absolutely critical to economic success in this heterogeneous, stacked, tight formation gas play.
Flawless, Safe Execution is the most critical part of the completion process. QA/QC standards require rigorous prejob and day-of-job fluid and proppant testing, the ability of all chemical add pumps to accurately deliver specified rates, and rigorous material balance tracking throughout the job. The job must not be pumped if all personnel, equipment, and materials are not fully prepared and up to spec.
Rigorous Engineering of completion designs is performed by a geographically dispersed, multi-disciplinary team, using petrophysical, reservoir, and frac design models to assure the most optimum design based on all available data and knowledge. The petrophysical model uses standard log data to estimate reservoir properties and mechanical rock properties. Log data is seamlessly converted into layer data for input into frac and reservoir models. Designs are optimized for each well based on predicted fracture characteristics and reservoir performance. Data is exchanged via a secure interactive web-based system. Data flow and work processes are well mapped and highly efficient.
Systematic Learning is pursued through comprehensive postcompletion well reviews. Frac design and reservoir models are re-run on every completion to help explain actual well performance versus pre-completion estimates. Production logs and frac diagnostic data also aid in understanding well results. The petrophysical, fracture stimulation, and reservoir models are periodically updated to incorporate learnings. Precompletion predictability has improved substantially.
The application of this model on 99 wells completed in 2002 has resulted in a 20% improvement in production and estimated ultimate recovery. Additionally, drilling costs have been reduced by 5%. Cost per unit gas volume produced has improved by 27%. Continued improvement in reservoir predictability will allow better optimization of top-quartile wells by focusing strongly on frac length and conductivity optimization, and of lower-quartile wells by minimizing the completion to only those few contributing sands.
Modeling Fracture Tip Screenout and Application for Fracture Height Growth Control
Authors: Bai M. , Morales R. H. , Suarez-Rivera R. , Norman W. D. , Green S. 
Published: December 2007

Abstract
This paper discusses the use of numerical simulations for predicting the onset and development of fracture tip screenout (TSO). It presents a parametric study for fracture containment to prevent height growth into water boundaries or a gas cap, under conditions that approximately simulate Gulf of Mexico reservoirs (weakly consolidated, high permeability soft formations). Different typical field cases were analyzed to demonstrate height containment at TSO conditions. The perforation interval is critical to height containment, with perforation height of only a fraction of the total pay interval required in some cases in order to create TSO.
A Cost Effective Approach to Modeling and Managing Large Gas Fields
Authors: Yee David , Poitevien Ricot 
Published: December 2007

Abstract
Management of gas reservoirs can be a difficult task if there is a varying degree of interference between wells. This difficulty increases with well count and the number of compressors and inter-connected processing plants. Numerical simulation of the integrated network and reservoir can help substantially. However, stability issues in complex networks and extensive data requirements have made simulation costly for large and complex projects.
With an extremely stable and efficient numerical model combined with data preparation techniques that rely on the use of existing databases and automated techniques, as well as streamlined history matching approaches, it has now become economically viable to use integrated models for large shallow gas properties. Without such a model to predict future performance, there is significant risk of over-building and over-drilling for future development. This paper discusses the setup, calibration and day to day use of an integrated model for a shallow gas field in Southern Saskatchewan, Canada.
Drift-Flux Modeling of Multiphase Flow in Wellbores
Authors: Shi H. , Holmes J. A. , Durlofsky L. J. , Aziz K. , Diaz L. R. , Alkaya B. , Oddie G. 
Published: December 2007

Abstract
Drift-flux modeling techniques are commonly used to represent two and three-phase flow in pipes and wellbores. Unlike mechanistic models, drift-flux models are continuous, differentiable and relatively fast to compute, so they are well suited for use in wellbore flow models within reservoir simulators. Drift-flux models require a number of empirical parameters. Most of the parameters used in current simulators were determined from experiments in small diameter (2 inch or less) pipes. These parameters may not be directly applicable to flow in wellbores or surface facilities, however, as the flow mechanisms in small pipes can differ qualitatively from those in large pipes. In order to evaluate and extend current drift-flux models, an extensive experimental program was initiated. The experiments entailed measurement of water-gas, oil-water and oil-water-gas flows in a 15 cm diameter, 11 m long plexiglass pipe at 8 deviations ranging from vertical to slightly downward. In this paper, these experimental data are used to determine drift-flux parameters for steady state two-phase flows of water-gas and oil-water in large-diameter pipes at inclinations ranging from vertical to near-horizontal. The parameters are determined using an optimization technique that minimizes the difference between experimental and model predictions for holdup. It is shown that the optimized parameters provide considerably better agreement with the experimental data than do the existing default parameters.
Probabilistic/Mechanistic Modeling of Slug Length Distribution in a Horizontal Pipeline
Authors: Al-safran E. M. , Sarica C. , Zhang H. Q. , Brill J. P. 
Published: December 2007

Abstract
A Probabilistic/mechanistic modeling was carried out to develop a predictive model for fully developed slug length distribution in horizontal pipeline. Statistical analysis suggested the appropriateness of a Log-Normal model over an Inverse Gaussian model for predicting slug length distribution. A total of 64 data sets were used to empirically correlate the Log-Normal model. Two empirical relationships for mean slug length and slug length standard deviation were developed. A statistical analysis revealed that, in addition to pipe diameter and mixture velocity, volumetric flow rate of the liquid film in the bubble region and the momentum exchange between the slug body and the liquid film are strongly correlated to mean slug length at a 5% significance level. The slug length standard deviation was found to have a significant correlation with film liquid holdup and momentum exchange. A model validation study demonstrated the capability of the probabilistic/mechanistic model to reproduce the experimental data with a satisfactory match. The match was improved when the developed correlations were tuned using the statistical confidence intervals of their coefficients.
Segregated Modeling of Oil-Water Flows
Authors: Shi H. , Jepson W. P. , Rhyne L. D. 
Published: December 2007

Abstract
A four-layer model was developed for horizontal and near horizontal oil-water flows. The four layers consist of pure water, oil-in-water dispersion, water-in-oil dispersion, and pure oil. The two dispersed layers are known to have significantly different viscosities. Therefore, the four-layer model provides a more comprehensive description and better modeling of the phase distribution and velocity profile as compared to earlier modeling efforts using two- and three-layers. Furthermore, the four-layer model uses a more accurate estimate of the mixture layer viscosities as compared to prior work using a simple volumetric averaging approach. The definition of the boundary between the two mixture layers was based on experimental phase-inversion measurements.
This four-layer model is based on experimental work performed on horizontal oil-water flows in a 10-cm diameter and 40-m long pipeline. Flow characteristics including pressure gradient, phase distribution and velocity profile across the pipe, and phase inversion point were measured for an oil and ASTM seawater system. Input water cuts between 0 to 100% were examined at mixture velocities ranging from 0.4 m/s to 3.0 m/s. The system was maintained at 25°C and 0.136 MPa. The model predictions are in good agreement with the experimental data. A multi-layer model is also proposed as the general form of segregated flow model, which can be used for Computational Fluid Dynamics (CFD) modeling efforts. CFD using a preliminary multi-layer model provided reasonable estimates of pressure drop.
A Compendium of Directional Calculations Based on the Minimum Curvature Method
Authors: Sawaryn S. J. , Thorogood J. L. 
Published: December 2007

Abstract
The minimum curvature method has emerged as the accepted industry standard for the calculation of 3D directional surveys. Using this model, the well's trajectory is represented by a series of circular arcs and straight lines. Collections of other points, lines and planes can be used to represent features such as adjacent wells, lease lines, geological targets and faults. The relationships between these objects have simple geometrical interpretations, making them amenable to mathematical treatment. The calculations are now used extensively in 3D imaging and directional collision scans, making them both business and safety critical. However, references for the calculations are incomplete, scattered in the literature and have no systematic mathematical treatment. These features make programming a consistent and reliable set of algorithms more difficult. Increased standardisation is needed.
Investigation shows that iterative schemes have been used where explicit solutions are possible. Explicit calculations are preferred because they confer numerical predictability and stability. Though vector methods were frequently adopted in the early stages of the published derivations, opportunities for simplification were missed because of premature translation to Cartesian coordinates.
This paper contains a compendium of algorithms based on the minimum curvature method (includes co-ordinate reference frames, toolface, interpolation, intersection with a target plane, minimum and maximum TVD in a horizontal section, point closest to a circular arc, survey station to a target position with and without the direction defined, nudges and steering runs). Consistent, vector methods have been used throughout with improvements in mathematical efficiency, stability and predictability of behaviour. The resulting algorithms are also simpler and more cost effective to code and test. This paper describes the practical context in which each of the algorithms is applied and enumerates some key tests that need to be performed.
Engineering Aspects of LWD Quadrupole Measurements and Field Test Results
Authors: Dubinsky V. , Tang X. M. , Bolshakov A. , Patterson D. 
Published: December 2007

Abstract
This paper presents the principle and engineering aspects of an LWD quadrupole shear wave tool. Extensive theoretical study and a series of laboratory and field experiments have been conducted to verify that the quadrupole measurements can determine the true shear velocity of the formation. Experimental results based on the actual laboratory and downhole while drilling measurements are presented in this paper. A multipole (i.e., monopole, dipole, and quadrupole) LWD acoustic tool has been constructed. This tool allows downhole recording of raw and stacked signals acquired by individual receiver elements of the tool. This tool consists of a universal source, which can operate at different frequencies in all three modes, i.e., monopole, dipole, and quadrupole. The six-station receiver array, with four individual receiver elements per station, permits signal acquisition in all these modes. In addition, a triaxial accelerometer system is used to monitor drilling dynamics while drilling.
By making multiple snapshots of the signals in different modes downhole for various drilling conditions, we demonstrate that, when operating in the quadrupole mode, the acoustic signals acquired by the LWD tool possess the true quadrupole characteristics. Comparison of the dipole, monopole, and quadrupole signatures clearly demonstrates how common mode noise is efficiently suppressed in the quadrupole mode. The result shows that even in the case of severe lateral vibrations the combined quadrupole signal provides satisfactory shear wave measurements. The data processing/analysis results are presented. Field-measured quadrupole LWD shear data are evaluated for different drilling scenarios.
LNG: A Proven Stranded Gas Monetization Option
Authors: Coyle David , Durr Charles , Shah Pankaj 
Published: December 2007

Abstract
LNG is a proven gas monetization option that has grown over the past 30 years from a 3 MMTPA industry in the early 1970s to 106 MMTPA industry in 2001. Even so, LNG today accounts for only about 6% of the total natural gas consumed worldwide. The growth in LNG is forecast to remain strong in the coming decade. The ability of the LNG option to continue to compete with existing and emerging gas monetization options will depend on the industry's success in reducing cost throughout the LNG value chain and maintaining exceptional safety, reliability, and environmental performance.
This paper reviews the different components of the LNG value chain from the gas field to the eventual consumer with emphasis on liquefaction plant and regasification terminal. The paper addresses feed gas treatment, liquefaction process technologies, utilities and typical CAPEX for the LNG liquefaction facility. For regasification terminals, the paper will describe off-loading systems, storage tanks, regasification process, vaporizer designs, safety issues and typical CAPEX.
The engineering of LNG liquefaction and regasification facilities is considered a mature technology. However, there are several developments that have or will lead to reduction in life cycle cost of these facilities making LNG a more competitive gas monetization option. These developments include large capacity LNG plants, use of large single shaft gas turbine drivers, all electric drives, and offshore LNG facilities.