bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploiting High-Rate Injection and Fracturing To Improve Areal Thermal Conformance in Cyclic Steam Stimulation
Authors: Boone Thomas J. , Gallant Richard J. , Kry P. R. 
Published: December 2007

Summary
Achieving good areal thermal conformance is a key component in developing an effective steam-based recovery process. This paper describes a test where high-rate pulsed injection (HRPI) of steam has been used to improve areal thermal conformance as part of an operation that uses cyclic steam stimulation. In this process, steam was repeatedly injected at high rates [≈ 2000 m3/d, cold water equivalent volume (CWEV)] for relatively short periods (hours), rather than constantly injecting at lower rates (200 to 300 m3/d) for several weeks or months. The objective of the high-rate injection was to create extensive horizontal fractures at a well. Then, the heat transport capability of steam flow in the fractures was exploited to improve areal thermal conformance. The well at which this test was conducted is surrounded by six observation wells. In the previous 5 years of cyclic steam stimulation at the injector, little temperature change had occurred in these wells. Within hours of starting HRPI, significant heat was seen at three of the surrounding observation wells. After several pulses, a fourth observation well showed significant temperature increases. This paper documents the procedures used in the test and data collected during the test.
A New Wireline Tool for In-Situ Stress Measurements
Authors: Thiercelin M. J. , Plumb R. A. , Desroches Jean , Bixenman P. W. , Jonas J. K. , Davie W. R. 
Published: December 2007

Summary
This paper describes the development of a wireline tool for open-hole stress measurements. This tool includes a straddle packer module comprising surface controlled valves, pressure gauges, and a downhole pump. Stress measurements are either based on the micro-hydraulic fracturing technique or the H.T.P.F. technique (Hydraulic Tests on Pre-existing Fracture). Before presenting the tool, we derive specifications for obtaining reliable stress measurements. The maximum differential pressure (which is the interval pressure minus wellbore pressure) that the tool can currently sustain is 28 MPa (4000 psi) and flow rates of the order of 1 liter/min can be achieved. Results of field tests are described which demonstrate the high quality of the tool response.
Physical Explanations of Non-Darcy Effects for Fluid Flow in Porous Media
Authors: Ma Huiping , Ruth Douglas 
Published: December 2007

Summary
The nature of nonlinear flow in porous media is analyzed by means of the volumetric averaging approach for a medium modeled by di-verging/converging capillaries. To clarify the mechanism responsible for the nonlinearity, a physical explanation is deduced for the dispersion term in the averaged momentum equation. With the present periodical model, the numerically obtained microscopic flow fields, in association with the macroscopic coefficients calculated by the average momentum balance, indicated quantitatively that the microscopic inertial phenomena, which lead to distorted pore velocity and pressure fields, is the fundamental reason for the onset of nonlinear effects as filtration velocity increases.
Pushing the Limits for Extended Reach Drilling: New World Record From Platform Statfjord C, Well C2
Authors: Alfsen Turid E. , Heggen Steinar , Blikra Harald , Tjøtta Helge 
Published: December 2007

Summary
Well 33/9-C2 with its horizontal reach of 7290 m is a new world record in extended-reach drilling. The well was drilled from the Statfjord C platform in the North Sea, Norwegian sector, and has a total length of 8761 m MD. This paper will describe the planning techniques used, with focus on coping with limitations in equipment and formation. It will also present a case history of the drilling operations including operational experience gained and comparisons between simulated drilling parameters and field data.
A Nonlinear Approximation for the Pressure Behavior of Heterogeneous Reservoirs
Authors: Kuchuk Fikri J. , Habashy Tarek M. , Torres-Verdin Carlos 
Published: December 2007

Abstract
Recent years have seen extensive use of analytical techniques to study pressure behavior in layered, laterally, and radially composite systems. In this paper, we present a new approximate method to describe the transient pressure behavior of heterogeneous reservoirs. The reservoir is subdivided into a collection of subregions with different rock properties embedded in an otherwise homogeneous background that is defined as a homogeneous region, a stack of layers, or a radially symmetric composite structure. However, both the background medium and the anomalous region may exhibit three-dimensional (3D) anisotropy. The proposed method of solution is formulated in the Laplace transform domain wherein both wellbore storage and skin effects can be included in an algebraic fashion. Beginning with the integral equation solution for the pressure diffusion in porous media, we derive a nonlinear approximation with respect to the spatial variations in reservoir properties. This solution may accurately handle high contrasts in reservoir properties as well as large anomalous regions such as deltaic sandstones and sorted channels systems. For small contrasts, the proposed nonlinear approximation reduces to the Born approximation. We present comparison tests with available analytical solutions such as those related to finite-width strips.
Deepwater Gulf of Mexico Turbidites— Compaction Effects on Porosity and Permeability
Authors: Ostermeier R. M. 
Published: December 2007

Summary
The deepwater Gulf of Mexico is now a major area of activity for the U.S. oil industry. Compaction causes particular concern because most prospective deepwater reservoirs are highly geo-pressured and many have limited aquifer support; water injection may also be problematic. Thus, economic development may require significant drawdowns with ensuing compaction and its attendant problems.
To address some of the issues associated with compaction, we initiated a special core-analysis program to study compaction effects on turbidite sand porosity and permeability specifically. This program also addressed a number of subsidiary but no less important issues, such as sample characterization and quality, sample preparation, and test procedures. These issues are particularly pertinent, because Gulf of Mexico turbidites are generally unconsolidated, loose sands, and are thus susceptible to a whole array of potentially serious core-disturbing processes.
One key result of the special core analysis program is that turbidite compressibilities exhibit large variations in both magnitude and stress dependence. These variations correlate with creep response in the laboratory measurements. The data suggest creep may be important because observed creep relaxation rates, although slow on a laboratory time scale, are much faster than typical reservoir drawdown rates.
The effects of compaction on permeability are significant. To eliminate complicating effects caused by fines movement, we made oil flow measurements at initial water saturation. The measurements indicate compaction reduces permeability four to five times more than porosity on a relative basis.
Integrated Geostatistics For Modeling Fluid Contacts and Shales in Prudhoe Bay
Authors: Pérez Godofredo , Chopra A. K. , Severson C. D. 
Published: December 2007

Summary
Geostatistics techniques are being used increasingly to model reservoir heterogeneity at a wide range of scales. A variety of techniques is now available with differing underlying assumptions, complexity, and applications. This paper introduces a novel method of geostatistics to model dynamic gas-oil contacts and shales in the Prudhoe Bay reservoir.
The method integrates reservoir description and surveillance data within the same geostatistical framework. Surveillance logs and shale data are transformed to indicator variables. These variables are used to evaluate vertical and horizontal spatial correlation and cross-correlation of gas and shale at different times and to develop variogram models. Conditional simulation techniques are used to generate multiple three-dimensional (3D) descriptions of gas and shales that provide a measure of uncertainty. These techniques capture the complex 3D distribution of gas-oil contacts through time.
We compare results of the geostatistical method with conventional techniques as well as with infill wells drilled after the study. Predicted gas-oil contacts and shale distributions are in close agreement with gas-oil contacts observed at infill wells.
In-Situ Optical Fluid Analysis as an Aid to Wireline Formation Sampling
Authors: Smits A. R. , Fincher D. V. , Nishida Katsuhiko , Mullins O. C. , Schroeder R. J. , Yamate Tsutomu 
Published: December 2007

Summary
This paper describes the basic theory of operation for a newly developed wireline tool that uses optical principles for continuous analysis of fluid in the flowline of a wireline formation fluid sampler. The tool has a visible and near-infrared absorption spectrometer for fluid discrimination and a refractometer for free gas detection. The Effective Flow Stream (EFS) model has been developed to interpret the measured data and to estimate the volume fraction of water and oil in the tool's flowline for biphasic flow. For triphasic flow, the technique can give a quantitative estimate of water, along with a qualitative evaluation of the amount of oil and gas. We present an example of showing tool response in the laboratory, introduce applications of the technique for aiding formation sampling, and, finally, illustrate the implementation of this technique with field examples.
A Parameter-Based Approach for Two-Phase-Equilibrium Prediction With Cubic Equations of State
Authors: Kaul Pradeep , Thrasher R. L. 
Published: December 2007

Summary
A parameter-based approach for two-phase-equilibrium prediction that uses the two-parameter Peng-Robinson equation of state (EOS) has been developed. This approach takes advantage of the special mathematical forms of the ideal mixing and excess parts of the Gibb's free energy to reduce the NC-component equilibrium problem to a minimization problem in three or four variables, depending on whether binary interaction coefficients (BIC's) are zero or nonzero. The Gibb's free energy is minimized in two steps. The ideal mixing term is minimized first subject to certain constraints that include the mixing rules for the EOS parameters. A second minimization is performed over the total Gibb's free energy with the Lagrange multipliers from the first minimization as a reduced set of variables in place of the usual component-related variables.
The new approach has been applied to develop parameter-based versions of the Newton-Raphson and trust-region methods for performing flash calculations as well as the phase-stability test to handle the transition from one to two phases. These methods have been implemented in computer programs and tested on phase-behavior problems taken from the petroleum literature.
In the case of zero BIC's, the reduction in the number of variables produces substantial reduction in computational cost compared with component-based methods, especially as the number of components increases, while convergence behavior is essentially unchanged. For the nonzero BIC case, however, a practical implementation requires the introduction of approximations that compromise convergence and offset the lower cost per iteration.
A Simple Predictive Calculation for the Viscosity of Liquid Phase Reservoir Fluids With High Accuracy for CO2 Mixtures
Authors: Fong W. S. , Sandler S. I. , Emanuel A. S. 
Published: December 2007

Abstract
A simple and accurate correlation has been developed for predicting the viscosity of CO2-reservoir oil mixtures from composition. The method is suitable for equation-of-state based reservoir simulations, and is useful for a wide range of oil viscosities from 0.2 to 400,000 cp. The correlation is based on a generalized power mixing rule and was developed with experimental viscosity data from 20 oil systems, ranging from light oils to heavy bitumens. The pressure-temperature range of the data was 14.7–7000 psi and 70–255°F. A Peng-Robinson equation of state characterization was developed for each of the oils to match PVT data. This characterization was then used in the viscosity correlation. Accurate predictions require an experimental value of CO2-free reservoir oil viscosity at reservoir temperature and above bubble point pressure. For the oils and bitumens tested, this method predicts oil-solution gas- CO2 mixture viscosity with 12.5% average absolute deviation (AAD).
Simulation of Production and Injection Performance of Gas Storage Caverns in Salt Formations
Authors: Hagoort Jacques 
Published: December 2007

Summary
This paper presents a simple yet comprehensive mathematical model for simulation of injection and production performance of gas storage caverns in salt formations. The model predicts the pressure and temperature of the gas in the cavern and at the wellhead for an arbitrary sequence of production and injection cycles. The model incorporates nonideal gas properties, thermodynamic heat effects associated with gas expansion and compression in the cavern and tubing, heat exchange with the surrounding salt formation, and nonuniform initial temperatures but does not include rock-mechanical effects. The model is based on a mass and energy balance for the gas-filled cavern and on the Bernoulli equation and energy balance for flow in the wellbore. Cavern equations are solved iteratively at successive timesteps, and wellbore equations are solved within an iteration cycle of the cavern equations. Gas properties are calculated internally with generally accepted correlations and basic thermodynamic relations. Example calculations show that the initial temperature distribution has a strong effect on production performance of a typical gas storage cavern. The primary application of the model is in the design, planning, and operation of gas storage projects.
System Safety Analysis of Well-Control Equipment
Authors: Fowler J. H. , Roche J. R. 
Published: December 2007

Summary
Two techniques are used for reliability analysis of a blowout preventer (BOP) and a hydraulic control system. Failure modes and effects analysis (FMEA) examines each part and the consequences of its malfunction. Fault tree analysis (FTA) traces undesired events to their causes. Reliability calculations and data sources are addressed.
Design, Drilling, and Testing of a Deviated HTHP Exploration Well in the North Sea
Authors: Seymour K. P. , MacAndrew Robert 
Published: December 2007

Summary
Significant quantities of hydrocarbon reserves are contained in North Sea high-temperature, high-pressure (HTHP) reservoirs. De-velopment of these reserves will require deviated wells. This paper outlines the planning, drilling, and testing of the first deviated HTHP well in the U.K. sector of the North Sea.
Dual Openhole Gravel Pack in Shaly Fine Sands
Authors: Moricca Giuseppe , Ripa Giuseppe , Rucci Domenico , Pitoni Enzo 
Published: December 2007

Summary
This paper discusses the design and execution of dual-zone gravel packs in very shaly and silty formations of median sand grain size less than 30 μm. An oversized gravel was selected for sand control and, as a consequence, the openhole gravel-pack technique was adopted to reduce the effect of intermixing between formation and gravel-pack sand. During the completions in the first five wells, we encountered and solved several operational problems, including those involving (1) borehole stability, (2) setting of inflatable packer for zone isolation, (3) hole preparation, and (4) gravel placement. From the lessons we learned, another 11 wells were completed with dual openhole gravel packs without significant problems. After 1 year of production, the flow performance from the wells met or exceeded the initial objectives.
Equilibrium and Stability of Static Interfaces in Biconical Pore Segments
Authors: Toledo Pedro G. , Scriven L. E. , Davis H. Ted 
Published: December 2007

Summary
The equilibrium and stability of interfaces largely set the fluid distribution in a porous medium. Here we determine the equilibrium and stability of axisymmetric interfaces, namely head and neck menisci, in biconical pore segments. We also report relationships between capillary pressure, Pc, and mercury volume, VHg, for stable interfaces. These results are used in our Monte Carlo simulation of volume-controlled mercury porosimetry.
New Electromagnetic Surveying/Ranging Method for Drilling Parallel Horizontal Twin Wells
Authors: Kuckes A. F. , Hay R. T. , McMahon Joseph , Nord A. G. , Schilling D. A. , Morden Jeff 
Published: December 2007

Summary
An electromagnetic source was used in conjunction with a measurement-while-drilling (MWD) survey instrument to drill two parallel horizontal wells with a vertical separation of 9 ± 2 m over a length of 600 m in Amoco's Wolf Lake field for steam-assisted gravity drainage of heavy oil. Existing wellbore survey methods are incapable of this level of precision because of cumulative survey error and associated position uncertainty. Using this new electromagnetic ranging technique, the twin wells were placed with better than 10 times the accuracy of gyro surveys.
Effects of Heterogeneity and Anisotropy on Probe Measured Permeabilities
Authors: Manrique Jorge F. , Kasap Ekrem , Georgi Dan 
Published: December 2007

Abstract
Numerical simulations and laboratory experiments were used to study effects of heterogeneity and anisotropy on probe measured permeabilities. Simulation results show that the geometric factors for unsteady-state flow measurements are not different from the ones obtained for steady-state. Effects of a nearby flow barrier on probe measured permeability are studied experimentally and numerically, and it is concluded that the effect of a local flow barrier is negligible when the barrier is located farther than one-half of a probe-tip diameter from the probe.
Probe measured permeability on a damaged formation is profoundly affected by the damaged zone thickness. Working with geometric factors, a methodology to obtain undamaged and damaged zone permeabilities, and damaged zone thickness is developed. To obtain such information uniquely three measurements with three different probe tip sizes are required.
The effects of anisotropy on probe measured permeability are also investigated by introducing tensorial permeability for probe measurements. Several simulation runs were performed for different anisotropy ratios at various cross-bedding angles. Results are presented in the form of dimensionless parameters that can be used to determine depositional dip angle and permeabilities in the principal directions.
Horizontal Well Acidizing of a Carbonate Formation: A Case History of Lisburne Treatments, Prudhoe Bay, Alaska
Authors: Krawietz T. E. , Rael E. L. 
Published: December 2007

Summary
Stimulating horizontal wells in carbonate formations can lead to significant increases in productivity if effective fluid diversion can be achieved. Many horizontal wells are completed with slotted or pre-drilled uncemented liners throughout long producing intervals. These completions prevent effective use of conventional cased-hole diverting techniques, such as ball sealers and some particulates. Stimulation fluids can be mechanically placed or diverted with such materials as particulates, foam, and/or high-viscosity fluids. A combination of nitrogen foam and viscous emulsified acid pumped through coiled tubing (CT) has been successfully used to treat horizontal wells in the Lisburne field at Prudhoe Bay, Alaska. This paper documents treating techniques and production results of acid stimulation treatments pumped in horizontal wells that are completed with slotted or predrilled uncemented liners throughout long producing intervals. Case histories of four wells are used to illustrate treatment designs and production response.
Improved Oil Recovery Using Horizontal Wells at Elk Hills, California
Authors: Gangle F. J. , Schultz K. L. , McJannet G. S. , Ezekwe N. 
Published: December 2007

Abstract
Eight horizontal wells have been drilled and completed in a steeply dipping Stevens sand reservoir in the Elk Hills field, Kern County, California.
The subject reservoir, called the Stevens 26R, is a turbidite channel sand deposit one mile wide, three miles long, and one mile deep. Formation beds have a gross thickness up to 1,500 feet and dips as high as 60 degrees on the flanks. The original oil column of 1,810 feet has been pulled down to 200 feet by continual production since 1976.
The reservoir management operating strategy has been full pressure maintenance by crestal gas injection since 1976. The steep dip of the formation makes gravity drainage the dominant drive mechanism. Additionally, improved recovery is coming from cycling dry gas through the large secondary gas cap region.
The prudent placement of the horizontal wells above the oil/water contact promises to improve oil recovery and extend the operating life of the reservoir. Field results are given to compare the performance of the horizontal wells with the conventional wells. The horizontal wells produce at higher rates, lower draw downs, and lower gas/oil ratio which will extend the life of the project and result in higher recovery.
Using Fracturing as a Technique for Controlling Formation Failure
Authors: Fletcher P. A. , Montgomery C. T. , Ramos G. G. , Miller M. E. , Rich D. A. , Guillory R. J. , Francis M. J. 
Published: December 2007

Summary
Conventional gravel-pack completions often reduce a well's productivity by increasing the completion skin. This paper describes a methodology backed by a systematic technique to predict the necessary drawdown, fracture length, and conductivity to prevent formation failure and remove the completion damage. This method enables the engineer to optimize the fracture dimensions while obtaining the necessary decrease in near-wellbore drawdown that would cause the unpacked perforation to fail. This technique will greatly reduce the chance for formation failure and improve the well performance without the need to gravel pack.
Multiple Realizations of the Permeability Field From Well Test Data
Authors: Oliver Dean S. 
Published: December 2007

Abstract
Although it is possible to generate smooth radially-symmetric permeability distributions that honor a given set of pressure data, the assumption of radial symmetry is unrealistic for most heterogeneous reservoirs. The alternative for generating two-dimensional permeability fields that honor the pressure data and a variogram, without the radial symmetry of the deterministic methods, has usually been to resort to Monte Carlo methods. In this paper I show that it is possible, using models which are linearized about the maximum likelihood point, to generate multiple realizations of the permeability field that are conditioned to well test data, point measurements of permeability, and the variogram. The proposed procedure is far more efficient than current simulated annealing or genetic algorithms and the resulting conditional simulations have no radial artifacts.
Fracture-Mechanics Analysis of the Breakdown Process in Minifracture or Leakoff Test
Authors: Detournay Emmanuel , Carbonell Roberto 
Published: December 2007

Summary
The breakdown pressure—the peak pressure that is reached during pressurization of the wellbore—is interpreted in this paper to correspond to a condition of unstable crack propagation. It is shown that the classical Hubbert and Willis14 and Haimson and Fairhurst9 breakdown criteria represent a condition of fracture initiation in the limiting case of fast and slow pressurization rate, respectively; and that the breakdown pressure, pb, could be either equal to or larger than the fracture-initiation pressure, pi.