bluuebunny/crossref_metadata_2025_split huggingface dataset:
Velocities in Developed Five-Spot Patterns
Authors: Parsons R.W. 
Published: December 2007

Laboratory experiments have shown that some oil recovery processes are rate sensitive, particularly Those employing surfactant-type materials. In this note, an ideal reservoir is analyzed to give a feel for proper rates in linear laboratory tests to best simulate proper rates in linear laboratory tests to best simulate a field pattern.We need to consider the distribution of frontal velocities* for field patterns. For the developed five-spot, velocities will range from very high in the well-bore vicinity to zero at the stagnation points halfway along each of the five-spot sides. Detailed frontal velocity distribution was determined from a computer streamline model for a homogeneous, isotropic, single mobility, confined five-spot octant. Each of the 12 equal volumetric rate stream channels in the octant had 40 cells with computer-generated values of volume and velocity.Fig. 1 shows the volumetric distribution of frontal velocities for the entire five-spot pattern (the same as for the octant). Velocities are on a normalized, but not dimensionless, basis, so the single curve applies for any pattern size, injection rate, and porosity. The median frontal velocity, 0.016, is that value at which half the five-spot volume has higher velocities and half lower. For example, a 10-acre five-spot with 20 percent porosity and an injection rate of 5 B/D-ft percent porosity and an injection rate of 5 B/D-ft would have a median frontal velocity of 0.016 X 5/(0.2 X the square root of 10) = 0.13 ft/D. Unless there is some other compelling consideration, this median value is probably a good single characterization of fluid velocity in a developed five-spot. Note that because of high near-wellbore velocities, the volumetric averaged velocity is somewhat higher than the median.A more detailed analysis would consider velocities at a displacement front in each of the stream channels as a function of total pattern injection. Fig. 2 shows the five-spot octant stream channels and location of a unit mobility ratio perfect piston front at various injection times. Velocities in Stream Channels 2, 4, 6, 8, 10, and 12 as a function of total pattern injection are shown in Fig. 3. Each curve is symmetrical about some vertical line. Consideration of Figs. 2 and 3 will give one a feet for just how realistic a particular linear laboratory experiment might be in simulating field five-spot rates.
P. 550
Estimating Flow Efficiency From Afterflow-Distorted Pressure Buildup Data
Authors: McKinley R.M. 
Published: December 2007

Since publishing the type-curve analysis method given in Ref. 1 for afterflow-distorted pressure; buildup data, I have received numerous queries on estimating the flow efficiency of a damaged well directly from the type-curve match. This note describes a method that gives a rough estimate of flow efficiency for wells with localized damage.Fig. 1 shows pressure buildup data computed during the afterflow period for a well producing at 60kh percent flow efficiency. In this figure, T = percent flow efficiency. In this figure, T = md-ft denotes transmissibility in units of, and F is thecp wellbore storage capacity in cu ft/psi, as defined below Eq. 5 in Ref. 1. If one assumes that this storage factor remains reasonably constant during the afterflow period, then the breakaway character of the type-curve match in Fig. 1 denotes localized wellbore damage with at least a 5:1 permeability reduction around the well. The departure of the data points in Fig. 1 from the T/F = 5,000 curve after a buildup of 80 to 100 psi denotes a transition from a state in which flow into the wellbore is determined by damage-zone resistance to a state in which formation resistance controls the flow. Conversely, pressure buildup before the departure represents pressure recovery across the damage zone. This is obviously a true statement for the two limiting cases ofno wellbore damage at all, andinfinitely large formation permeability beyond the damaged zone.
Statement validity for intermediate cases can be shown from the unit response formulation given in Ref. 1.
P. 696
The Effect of Temperature and Pressure on the Viscosity of Oil-Base Muds
Authors: McMordie W.C. , Bennett R.B. , Bland R.G. 
Published: December 2007

Introduction
The viscosity of oil-base muds can be determined over a wide range of temperature and pressure using the BHC Viscometer. This instrument consists of two concentric cylinders mounted in a 20,000-psig autoclave that has an upper operating-temperature limit of 650 degrees F. The inner cylinder, or rotor, is connected by a magnetic couple to a Haake Rotovisko. A detailed description of the instrument has been published previously.
In operating the BHC Viscometer, the autoclave is completely filled with mud and sealed. The rotor is rotated at a constant rate and the sample is allowed to reach an equilibrium temperature. The pressure is then adjusted with an auxiliary pump and the shear stress is recorded for each shear rate.
The instrument was calibrated by first calculating the shear rates from the viscometer dimensions. This method gave shear rates of 11, 21, 32, 64, 96, 191, 286, 573, and 860 sec-1. The mean shear-stress constant was then determined experimentally to be 8.1 dynes/cm2/scale part (1.6 lb/100 ft2/scale part).

Discussion
The best mathematical description of the viscosity of an oil-base mud at constant temperature and pressure is the power-law model. The linear form of this model is power-law model. The linear form of this model is(1)ln = ln K + n ln y
However, two sets of constants are required, one set for use at shear rates below ~ 200 sec and the other set for the higher shear rates.
The analysis of the pressure and temperature effects shows that the logarithm of the shear stress is directly proportional to the pressure and inversely proportional to proportional to the pressure and inversely proportional to the temperature. These relationships can be expressed by the following equations:(2)ln p,
JPT
P. 884
A Coupled Reservoir and Geomechanical Simulation System
Authors: Settari Antonin , Mounts F. M. 
Published: December 2007

SummaryCurrent simulation models do not account for the interactions among the geomechanical behavior, formation fracturing and multiphase flow, and heat transfer in porous media. This paper describes a method for modular coupling of a commercial reservoir simulator with a three-dimensional (3D) stress code and fracture-propagation model. The iteratively coupled system is equivalent to a fully coupled solution of flow and stress. The iterative method is very robust. An experience with acceleration of the iteration is described, and the utility of the method is demonstrated on examples. The comparison with an uncoupled solution shows that significantly different (and more realistic) answers are obtained with the coupled modeling. The current limitations and future work are also discussed.
Vapex: An Efficient Process for the Recovery of Heavy Oil and Bitumen
Authors: Das S. K. 
Published: December 2007

Summary
The Vapex (vapor extraction) process may be a viable technique for the recovery of highly viscous heavy oil and bitumen. The size of the estimated heavy oil and tar sand resources in the United States amounts to 100 billion bbl and 62 billion bbl of oil in place (OIP), respectively. Although this represents a small fraction of the total world reserves, it is about one-third of the total estimated crude oil discovered in the United States. The world estimate of this resource is about 6 trillion bbl, six times the conventional oil reserves, and may be the future source of energy. Efficient extraction of these highly viscous crude oils poses a serious challenge to petroleum engineers. In some of the heavy oil reservoirs steam flooding and in-situ combustion processes were partially successful. For thick tar sand reservoirs, the steam-assisted gravity drainage (SAGD) process proved to be effective. However, thermal processes, in addition to other disadvantages, suffer from energy inefficiency caused by heat losses.
The Vapex process involves injection of vaporized hydrocarbon solvents into heavy oil and bitumen reservoirs; the solvent-diluted oi1 drains by gravity to a horizontal production well. Recent research has shown that the process is highly energy efficient, environmentally friendly, causes in-situ upgrading, and requires low capital investment compared to its competitive process, SAGD. The applicability of the Vapex process may even surpass SAGD in thin reservoirs, reservoirs underlain by aquifer, offshore operations, etc. Some experimental results, a theoretical analysis, and the feasibility of this process for implementation in heavy oil and bitumen reservoirs will be presented.
World's First 4.5-in. Coiled-Tubing Pipeline
Authors: El-laithy W. F. 
Published: December 2007

Summary
Coiled tubing (CT) is a rapidly growing pipeline technology. Use of CT as pipeline is a new application to an existing technology. Until recently, CT was primarily used by service companies for CT workovers. As the technology expanded, the industry began using CT for other applications such as drilling, coring, logging, well cleanout operations, and artificial lift. As the tubing mills began producing larger sizes, the use of CT as pipelines was considered possible. The application of CT as a pipeline began in the Gulf of Mexico. The early results supported the application as being a low cost, time saving, economic alternative to conventional welded pipe for flowlines. CT applications have been used in 4 to 100 ft of water in the Gulf of Mexico area and the installation techniques have varied significantly.
In 1994, the Gulf of Suez Petroleum Co. (Gupco), a joint venture company between Amoco Production Co. and the Egyptian Petroleum Co., embarked on the first international application of the 3.5-in. coiled pipe with a dynamic lay procedure. The cost savings from the first two jobs were estimated to be in excess of 70% when compared to the traditional lay vessel charges. Ref. 1 presents engineering design and field experience. Subsequently, Gupco has taken a leading role in the application of CT technology with the 1996 installations of the first production of 4.5-in. coiled pipe, one of which is a record-setting 62,000-ft high-pressure water supply line. Cost savings of this larger diameter pipe are still yielding 55% over the conventional barge lay techniques. In this paper, we will cover the significant findings of that engineering work and present actual field case histories on Egypt's first 4.5-in. coiled pipeline projects.
Analytical Solutions for Waterfloods in Fractured Reservoirs Obtained by an Asymptotic Approximation
Authors: Rasmussen M. L. , Civan Faruk 
Published: December 2007

Summary
This analysis presents an approximation for the long-time evaluation of waterfloods in fractured reservoirs. The formulas for the approximate solution are easier to use than the exact results and lend themselves to the physical description of the propagation speed and the diffusive spreading of the wave front. A comparison of the approximate and exact results for a representative example shows excellent correlation, and the differences are well within the accuracy that can be expected in the practical representation of reservoir parameters.
Composite Production Riser—Testing and Qualification
Authors: Salama M. M. , Johnson D. B. , Long J. R. 
Published: December 2007

Summary
The production riser is a tension leg platform (TLP) component that lends itself to taking advantage of the unique properties of advanced composite materials. A composite production riser (CPR) has the potential to reduce capital expenditure and improve reliability for development of reservoirs in deep water because of its lighter weight, improved corrosion resistance, and excellent fatigue performance compared with steel risers. In 1995, a project was organized by several oil, service, and composite manufacturing companies and partially sponsored by the U.S. Dept. of Commerce Natl. Inst. of Standards and Technology Advanced Technology Program to develop a cost effective CPR for deepwater applications and to overcome the technical challenges in design, analysis, fabrication, and qualification of a CPR. A critical element of this project is the specification and implementation of a comprehensive testing program to confirm the advantages, validate the design, and establish the long-term performance of a CPR as well as to secure the confidence of both operational staff and certifying authorities. The testing program was designed to identify performance limitations, establish the failure envelope for the full-diameter CPR joints, and verify that the manufactured CPR meets the performance requirements for application on a TLP in the Gulf of Mexico. In addition, the testing program, combined with the analytical effort, was planned to establish statistical variations in strength factors and to generate data to design CPR's of different sizes and for different operating conditions. This will allow for site-specific qualification of a CPR with minimal testing. In this paper, we discuss the testing program, review its rationale, and present currently available results. Test results clearly illustrate that current state-of-practice for design and manufacturing of composite CPR joints are well advanced to achieve the required cost effectiveness and high reliability for use in deepwater developments.
Effect of Underinhibition With Methanol and Ethylene Glycol on the Hydrate-Control Process
Authors: Yousif M. H. 
Published: December 2007

Summary
Hydrate control can be achieved by chemical injection. Currently, methanol and ethylene glycol are the most widely used inhibitors in offshore hydrate control operations. To achieve effective hydrate inhibition, a sufficient amount of inhibitor must be injected to shift the thermodynamic equilibrium condition for hydrate formation outside the pipeline operating pressure and temperature. Recently published field experiments showed that hydrate blockages form more readily in underinhibited systems than in systems completely without inhibitor. A laboratory study is conducted to determine the effect of low concentration (1 to 5 wt%) methanol and ethylene glycol on the hydrate formation process. The results show that, although these chemicals are effective hydrate inhibitors when added in sufficient quantities, they actually enhance the rate of hydrate formation when added at low concentrations to the water. Furthermore, the presence of these chemicals seems to affect the size of the forming hydrate particles.
Delineation of Air/Water Capillary Transition Zone From GPR Data
Authors: Nguyen Buu-Long , Bruining Johannes , Slob E. C. , Hopman Victor 
Published: December 2007

Summary
Spilled petroleum products spread laterally in the capillary transition zone above the water table. Ground penetrating radar (GPR) is a technique that can potentially delineate the air/water capillary transition zone (CTZ), because a varying water content strongly influences the reflected signal through its effect on the electrical properties. The vertical water distribution is determined on the pore scale by the grain size distribution and on the reservoir scale, mainly, by the permeability distribution. We present the integral equations for the reflected signal from a inhomogeneous slab with a depth-dependent dielectric constant and electrical conductivity. The numerical solution of the equations allows us to compute the signal reflected from different sand profiles. The results show that the reflected signal is strongly influenced by both the grain size distribution and the variation in permeability. A strong frequency dependence is also observed. We present a two-dimensional GPR profile measured in the field that shows a clear effect of the CTZ on the reflection of the radar signal. All these results are considered of importance for the interpretation of GPR data involving the capillary transition zone.
The Athel: A Challenging Formation in South Oman
Authors: O'Dell P. M. 
Published: December 2007

Summary
The Athel silicilyte is a deep, tight formation containing light oil and dissolved sour gas. Because the potential volume is large, there is interest in early development. However, because individual wells are very expensive, every opportunity to gather information must be used. Well testing (production tests, pressure/volume/temperature (PVT) sampling, production logging runs, and pressure transient tests) has been used extensively to characterize the reservoir, to guide appraisal activities, and to shape the ultimate development. Key issues to be resolved before development are initial and sustained productivity and project costs.
Production tests have demonstrated both challenges and opportunities in producing from this unique formation. Pressure transient tests have indicated that effective reservoir permeability is one-tenth of cleaned core plug permeability. The difference is likely caused by some combination of sealed fractures and the plugging effects of bitumen in the reservoir. Production logging has been used to measure the fraction of pay contributing to production. Reservoir simulation models, based on well test results, have been used to predict initial rates and ultimate recoveries for various well types (vertical, multiple drainhole, and multiple hydraulic fractures). Project costs (number of wells required) are based on these reservoir simulation results.
Rig Site and Laboratory Use of CWT Acoustic Velocity Measurements on Cuttings
Authors: Nes O. -M. , Horsrud Per , SØnstebØ E. F. , Holt R. M. , Ese A. M. , Økland Dag , KjØrholt Halvor 
Published: December 2007

Summary
A continuous wave technique (CWT) for measurement of acoustic phase velocities on cuttings is presented. The equipment is particularly well suited for testing of small samples like cuttings, and measurements, even on sub-mm-thick shale cuttings, have been performed. This yields potential access to a new source of data on the drilled formation that can also be attained in quasireal time at the rig site. The prototype equipment developed is portable, fast, and easy to use. Tests have been performed both at the rig site and in the laboratory. Potential applications include estimation of mechanical properties of shales, effects of various fluids and drilling muds, estimation of seismic parameters, and estimation of pore pressure.
Data Validation: Key to Development of an Integrated Reservoir Model for the Wara Formation, Greater Burgan Field
Authors: Pederson J. M. , Moon M. S. , Al-Ajeel H. Y. 
Published: December 2007

Summary
Prior coarse grid simulation models in the Greater Burgan field were unable to capture the stratigraphically diverse nature of the Wara reservoir and accurately match the existing historical data, resulting in unrealistic predictions of fluid flow from individual reservoir layers. Most simulation failures are blamed on the inability to correctly model reservoir heterogeneity rather than problems associated with the data it is trying to match. In reality it is probably a function of both. In this paper, we emphasize the importance of a systematic review of historical production data to ensure the accurate initialization of a simulation model and to assess whether a full history match should or should not be undertaken.
Not only does there need to be sufficient geologic and engineering detail to accurately characterize the fluid and flow properties of the Wara reservoir, but, more importantly, issues involving the validity, accuracy, and lack of historic data need to be addressed before deciding whether a reasonable reservoir model for history match can be developed. The reservoir size, long history, and high production rates of the Greater Burgan field magnify the impact and highlight the importance of correcting data errors and recognizing data uncertainty and gaps.
Compositional and Black Oil Reservoir Simulation
Authors: Coats K. H. , Thomas L. K. , Pierson R. G. 
Published: December 2007

SummaryThis paper describes a three-dimensional (3D), three-phase reservoir simulation model for black oil and compositional applications. Both implicit pressure, explicit saturation/concentration (IMPES) and fully implicit formulations are included. The relaxed volume balance concept effectively conserves mass and volume and reduces Newton iterations in both formulations. A new implicit well rate calculation method improves IMPES stability. It approximates wellbore crossflow effects with high efficiency and relative simplicity in both IMPES and fully implicit formulations. Multiphase flow in the tubing and near-well non-Darcy gas flow effects are treated implicitly.Initial saturations are calculated as a function of water/oil and gas/oil capillary pressures, which are optionally dependent upon the Leverett J function. A normalization of the relative permeability and capillary pressure curves is used to calculate these terms as a function of rock type and gridblock residual saturations.Example problems are presented, including several of the SPE comparative solution problems and field simulations.
A Hybrid Markov Chain Monte Carlo Method for Generating Permeability Fields Conditioned to Multiwell Pressure Data and Prior Information
Authors: Bonet-Cunha Luciane , Oliver D. S. , Redner R. A. , Reynolds A. C. 
Published: December 2007

SummaryIt is necessary to construct and sample the a posteriori probability density functions (pdf's) for the rock property fields to properly evaluate the uncertainty in reservoir performance predictions. In this work, the a posteriori pdf is constructed based on prior means and variograms (covariance function) for log-permeability and multiwell pressure data. Within the context of sampling the probability density function, we argue that the notion of equally probable realizations is the wrong paradigm for reservoir characterization. If the simulation of Gaussian random fields with a known variogram is the objective, it is shown that the variogram should not be incorporated directly into the objective function if simulated annealing (SA) is applied either to sample the a posteriori pdf or to estimate a global minimum of the associated objective function. It is shown that the hybrid Markov chain Monte Carlo (MCMC) method provides a way to explore more fully the set of plausible log-permeability fields and does not suffer from the high rejection rates of more standard MCMC methods.
Characterization of In-Situ Fluid Responses by Use of Optical Fluid Analysis
Authors: Felling M. M. , Morris C. W. 
Published: December 2007

Summary
Experiments were performed to quantify the light transmittance and optical density (OD) characteristics of more than 75 fluid samples, including hydrocarbons, formation waters, drilling mud systems, mud filtrates, and mixtures of these fluids. A catalog of characteristic optical fluid analyzer (OFA, Schlumberger Wireline & Testing, Houston) responses has been developed to aid in real-time fluid identification applications. Hydrocarbon responses were found to show a strong correlation between oil gravity and OD. Downhole oil gravity can be estimated from the OFA response by comparison with the database. A new technique for minimizing oil sample contamination by various oil-base mud (OBM) filtrates is proposed. Furthermore, a means is suggested for distinguishing between OBM filtrates and formation hydrocarbons. Several field examples are presented to illustrate the application of the techniques introduced.