bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cooperative Research—A Route To Reduce the Environmental Impact of Drilling Fluids
Authors: Oakley D. J. , Morrison A. , Burdis I. , Jones K. G. 
Published: December 2007

Summary
Increasing environmental constraints on use of oil-based drilling fluids have fluids have prompted close cooperation between operators and service companies to maintain the technical performance of drilling fluids while reducing oil discharge. This paper describes how Amerada Hess Ltd. (AHL) and Intl. Drilling Fluids Ltd. (IDF) cooperated by extending laboratory developments into controlled field trials and how feedback from the field has allowed rapid progress toward performance and ecological goals. We achieved progress toward performance and ecological goals. We achieved success through two developments. First, as a result of a jointly funded research project, we developed a novel, oil-free, highly inhibitive water-based drilling fluid. The inhibition offered by this fluid approaches that offered by oil-based fluids. Second, we developed invert-emulsion and direct-emulsion fluids with low oil/water ratios for low oil-on-cuttings applications. The cooperative process improved the technical performance of these fluids demonstrably and reduced the oil on cuttings.
Internal Blowouts, Cratering, Casing Setting Depths, and the Location of Subsurface Safety Valves
Authors: Walters J. V. 
Published: December 2007

Summary
This paper promotes industry awareness of the potential mechanisms that may take place in the rare event of a loss of well control and how these mechanisms may be assessed for field-specific conditions. This is particularly important when exploration/appraisal drilling involves penetrating highly overpressured accumulations. Depending on the geological burial history, these overpressures may be located in extremely competent or weakly consolidated formations, even at great depth. In-situ stress and rock-strength characteristics will play a major role with respect to the chances of reaching these target horizons successfully.
Automatic Grid Generation for Modeling Reservoir Heterogeneities
Authors: Garcia Michel H. , Journel André G. , Aziz Khalid 
Published: December 2007

Summary
An automatic grid-generation and -adjustment method is proposed to produce grids that may be used for finite-difference simulators. The resulting blocks are as homogeneous as possible with respect to specified parameters (e.g., porosity and permeability). Creating a grid of homogeneous blocks is desirable in flow simulation studies because it allows easier evaluation of the block average (effective) properties.
Investigation of Stress-Induced Borehole Enlargement Mechanisms by a Liquid-Metal Saturation Technique
Authors: Ewy Russell T. , Myer Larry R. , Cook Neville G. W. 
Published: December 2007

Summary
Stress-induced borehole enlargement was investigated with thick-walled hollow rock cylinders and a liquid-metal sample-preservation technique that permits observation of the microstructure of the broken rock. The observed breakouts are oriented and occur on the two opposite sides of the hole with the highest compressive-stress/compressive-strength ratio. Triangular (dog-eared) breakouts result from progressive spalling of thin rock slabs. The fundamental mechanism leading to this failure is the growth and interaction of microscopic cracks oriented parallel to the hole wall. Overbalance pressure in the hole changes this failure mechanism and greatly strengthens and stabilizes the hole wall. The apparent rock strength observed next to these small laboratory-scale model holes is higher than expected for field-scale holes.
Distribution of Residual Oil in Heterogeneous Carbonate Cores Using X-Ray CT
Authors: Hicks Paul J. , Deans Harry A. , Narayanan K. Ram 
Published: December 2007

Summary
The use of X-ray computerized tomography (CT) for the measurement of residual saturations and porosity distributions in heterogeneous carbonate cores is illustrated. Semivariograms of porosity are calculated and used to determine correlatiort lengths on the laboratory scale. The relationship between residual saturation and porosity is presented for two different cores.
Breaker Concentrations Required To Improve the Permeability of Proppant Packs Damaged by Concentrated Linear and Borate-Crosslinked Fracturing Fluids
Authors: Brannon H. D. , Pulsinelli R. J. 
Published: December 2007

Summary
The concentrations of an oxidative breaker required to reduce significantly the proppant-pack permeability damage caused by aqueous hydraulic fracturing fluids have been determined. Long-term, proppant-pack permeability testing was used to evaluate linear • and borate-crosslinked gels. Results indicate that increasing the breaker concentration can reduce proppant-pack permeability damage very effectively.
North Vickers East Waterflood Performance Prediction With Fractal Geostatistics
Authors: Di Julio Shoeleh S. 
Published: December 2007

Summary
A detailed geostatistical cross section, combined with a fine-grid streamtube calculation was used to predict the improvements of the North Vickers East waterflood project in Inglewood, CA. The intent was to test the hybrid finite-difference/streamtube technique (HST) to predict workover and realignment in a complex reservoir that was not easily modeled by conventional methods. Results indicate that HST may offer a method to represent the performance of such reservoirs without conventional history matching.
Incorporating Reservoir Heterogeneity With Geostatistics To Investigate Waterflood Recoveries
Authors: Wolcott Don S. , Chopra Anil K. 
Published: December 2007

Summary
This paper presents an investigation of infill drilling performance and reservoir continuity with geostatistics and a reservoir simulator. The geostatistical technique provides many possible realizations and realistic descriptions of reservoir heterogeneity. Correlation between recovery efficiency and thickness of individual sand subunits is shown. Additional recovery from infill drilling results from thin, discontinuous subunits. The technique may be applied to variations in continuity for other sandstone reservoirs.
The Use of Low-Density Particles for Gravel Packing a Highly Deviated Well
Authors: Bryant David , Hudson T. E. , Hoover S. W. 
Published: December 2007

Summary
Packing the annulus and perforations with gravel in highly deviated wells, especially horizontal wells, is difficult. As well deviation increases, pump rates and carrier-fluid viscosities must be increased to prevent particle settling. Increasing the viscosity reduces fluid leakoff and performation-pack efficiency. Placement efficiency improves as particle density, ρp, and carrier-fluid density, ρc, become closer. In an ideal system, these densities would be equal, ρp/ρc= 1, and no viscosity would be required, thereby improving fluid leakoff and perforation packing. Using sand as the packing material causes perforation packing. Using sand as the packing material causes hydrostatic overbalance, thus limiting the application of this system. The use of this technique with a pack material having a density of 40% less than that of sand eliminates the overbalance. This paper provides technology applicable to gravel packing highly deviated provides technology applicable to gravel packing highly deviated (horizontal) wells and describes (1) a new method for completing highly deviated wells with low-density particles (LDP's) and low ρpρc ratios, (2) computer simulations used to aid in the design of completion techniques, (3) printouts of the screenout pressure and pump rates, (4) well design schematics, (5) pack logs, pressure and pump rates, (4) well design schematics, (5) pack logs, and (6) well performance data.
Acoustic Logging Based on Wellbore Resonance
Authors: Medlin W. L. , Schmitt D. P. 
Published: December 2007

Summary
Wellbore resonance phenomena are the basis for a new acoustic logging method, the Stimulated Mode Acoustic Log (SMAL). The SMAL method stimulates a particular mode of wellbore vibration by exciting a resonance for that mode. Specific resonances are excited by driving an acoustic transmitter with a short tone burst of appropriate frequency. SMAL benefits include signal enhancement under adverse conditions, avoiding dispersion effects, propagating formation waves through cased and slotted liner completions, generating steady-state phase and amplitude data, and providing formation Q logs. All of these applications have arisen from studies of wellbore resonance phenomena through well logging and laboratory experiments. One means of study has been the wellbore excitation log, which shows the foot-by foot response of the wellbore to swept-frequency excitation across the acoustic band. Excitation logs show that resonances are sensitive to lithology and formation saturation conditions. Additional insight has been provided by generating standing waves under resonance conditions. This approach has led to a means of estimating a formation Q from the decay of standing tube waves. Q data, generated in this way, are consistent with laboratory data for core and quarry samples. A Q log, run through the gas, oil, and water legs of a thick Gulf Coast sand, is consistent with lab data for cores. Laboratory experiments in thick-wall pipe models have been another means of study. These field and laboratory investigations indicate that the combination of wellbore and logging tool behave somewhat like a resonance cavity for pressure waves in the wellbore fluid. Tool elements, especially the two ends, act as reflectors of fluid wave energy, giving rise to resonances and standing wave phenomena. The resonance characteristics of this cavity are dominated by the properties of the formation wall material and the coupling between the fluid and borehole wall. Other factors, such as fluid column and source resonances, play secondary roles. It is the strong dependence of resonances on formation properties that makes SMAL a valuable logging concept.
Nonplanar Fracture Propagation From a Horizontal Wellbore: Experimental Study
Authors: Abass H. H. , Hedayati Saeed , Meadows D. L. 
Published: December 2007

Summary
This paper presents experimental results related to hydraulic fracturing of a horizontal well, specifically the nonplanar fracture geometries resulting from fracture initiation and propagation. Experiments were designed to investigate nonplanar fracture geometries. This paper discusses how these nonplanar fractures can be responsible for premature screenout and excessive treatment pressure when a horizontal well is hydraulically fractured. Reasons for unsuccessful hydraulic fracturing treatments of a horizontal well are presented and recommendations to ensure clear communication channels between the wellbore and the fracture are given.
Advances in Characterizing Natural-Fracture Permeability From Mud-Log Data
Authors: Dyke C. G. , Wu Bailin , Milton-Tayler David 
Published: December 2007

SummarySmall drilling-fluid losses provide an accurate means of detecting conductive natural fractures and pinpointing potentially productive zones. We outline improved interpretation techniques that allow losses as small as 0.5 bbl to be used reliably as fracture permeability indicators. We compare results from four case histories with conventional fracture-detection methods.
Precipitation and Dissolution of Calcium Phosphonates for the Enhancement of Squeeze Lifetimes
Authors: Browning F. H. , Fogler H. S. 
Published: December 2007

Summary
Injection of scale inhibitors into a formation is a commonly used technique to prevent scale formation during oil production. The success of a "squeeze treatment" often is determined by its effective lifetime in inhibiting scale in a reservoir system, and this lifetime is dictated by the retention/release mechanisms of inhibitor in the reservoir. This paper focuses on a study of the precipitation/dissolution of calcium 1-hydroxyethylidene-l, 1-diphosphonic acid (HEDP)in a porous medium to elucidate the important factors that affect the release of this precipitate.
Experiments carried out in ceramic cores indicate that precipitation squeezes offer longer squeeze lifetimes and more HEDP retention than adsorption squeezes. Micromodel experiments show that the calcium-HEDP precipitate placed in porous media is made up of long, fibrous particles preferentially situated in pore throats. The elution from micromodels indicates that slow dissolution of apparently strong pore-throat plugs dictates the long tailing region. Finally, multiple-shut-in experiments performed in ceramic cores show that, while the amount of calcium-HEDP retention per shut-in does not increase with successive shut-ins, an enhanced returns effect is observed with respect to the squeeze lifetime.
Perturbation Boundary Element Method for Heterogeneous Reservoirs: Part 1—Steady-State Flow Problems
Authors: Sato Kozo , Horne Roland N. 
Published: December 2007

Summary
A perturbation boundary element method (BEM) for steady-state flow problems in heterogeneous media is developed, and various aspects of the model are tested. The perturbation series obtained by the BEM gives the complete solution for the original governing equation. For highly heterogeneous problems. Padè approximants are effective to accelerate the rate of convergence and to convert a divergent series into a convergent solution. Because the model does not suffer from numerical dispersion and grid orientation effects, it is possible to track streamlines accurately.
A Consistent Probabilistic Definition of Reserves
Authors: Capen E. C. 
Published: December 2007

SummaryUncertainty begs for a probabilistic treatment, and I know of almost no business filled with more uncertainty than that of the petroleum technologist in quest of oil and gas volume estimates. As in most uncertain endeavors, no single number captures the range that describes our lack of knowledge. Fortunately, the petroleum business has a mathematical ally, the central limit theorem. We know when we multiply variables (reservoir thickness, reservoir length, reservoir width, porosity, saturation, percent of hydrocarbon in place that can be produced with present technology and prices), we very quickly approach the log-normal distribution. We can make our estimates of proved, probable, and possible reserves all consistent if we make sure that each lies on the same log-normal probability distribution. We make still other improvements if we take these distributions for wells (or the basic unit on which we estimate reserves) and add the entire distribution to get reservoir, field, or company reserves. Simply adding proved reserves has never been a mathematically legal operation and ought to cease as quickly as possible. By striving for a distribution answer, we will find that we supply the kinds of numbers from "very safe" to "this is a dream" that will satisfy the various constituencies requiring volume information—governments, management, explorationists, bankers, and others. Still better, when estimates have probabilistic definitions, it is also possible to generate performance measures that hold the estimators to their promises.
Hydraulic Fracture Performance in the Moxa Arch Frontier Formation
Authors: Cipolla C. L. , Meehan D. N. , Stevens P. L. 
Published: December 2007

SummaryA comparison of hydraulic fracture performance during the initial development of the Moxa Arch Frontier sandstone in southwestern Wyoming (1975 to 1985) through infill development in 1989 to 1991 (320-acre spacing) and 1992 (160-acre spacing) is presented. The evaluation includes 3D hydraulic fracture modeling of reflected bottomhole pressures measured on 36 wells completed in 1992. In addition, in-situ stress test results from two wells are integrated with 3D fracture modeling and reservoir simulation of postfracture well performance to evaluate the evolution of fracture treatments over 17 years of development.The results from over 200 fracturing treatments were used to quantify the effect of treating fluid and proppant type on well performance. Detailed 3D fracture modeling illustrates the effects of in-situ stress and leakoff properties on fracture geometry. The results from 3D fracture modeling of 33 mini-fracs indicates vastly different fluid-loss behavior from well to well and a variation of in-situ stress within the Moxa Arch. The performance of 1992 infill wells stimulated with guar-based gels (borate and zirconium crosslinked) and sand is similar to initial development wells stimulated using guar-based crosslinked polymers and sand. However, 1989 to 1991 infill wells stimulated using CO2 foam and intermediate-strength ceramic proppants (ISP) did not perform as well as the water-based fluids and sand treatments. Fracturing net pressure data are presented that illustrate excess pressures owing to "proppant effects" and breakdown of stress barriers during fracturing that occurs in many treatments.
A Mechanistic Model for Computing Fluid Temperature Profiles in Gas-Lift Wells
Authors: Hasan A. R. , Kabir C. S. 
Published: December 2007

Summary
In a continuous-flow gas-lift operation, gas is injected down the annulus into the tubing near the top of perforations. The intrinsic idea is to aerate the liquid column, thus providing the necessary stimulus for fluid flow. Because the volumetric gas rate is dependent upon both the pressure and temperature at the depth of injection, accurate knowledge of these entities cannot be overemphasized for an efficient lift. In particular, the behavior of the nitrogen gas charged in the dome is critically dependent upon the temperature prediction for the optimal performance of the bellows-charged gas-lift valves.
Current practice entails use of a linear temperature profile for the annular fluid while applying empirical correlations for the tubing fluids. Improved temperature predictions are now possible for fluids in both conduits by modeling the heat and fluid flow problem at hand from first principles.
In this work, we present a mechanistic model for the flowing temperature of the annular gas and the gas/liquid two-phase mixture in the tubing as a function of both well depth and production time, regardless of the well deviation angle. The model is based on energy balance between the formation and fluids flowing through each conduit. While flowing down the annulus, the cold gas injected at the wellhead continues to gain heat. The heat-transfer rate for the annular gas depends on the relative temperatures of the formation and the tubing fluid. We assume unsteady-state heat transfer in the formation and steady-state heat transfer in the tubular for a continuous-flow gas-lift operation.
The analytic solution obtained affords flexibility to input any temperature distribution function (TD model) for modeling unsteady heat transfer in the formation. Rapid implementation of the new solution is possible because of its simplicity. Our results show that the temperature profiles in both flow conduits are nonlinear, unlike those used previously, particularly in the annulus. Variables, such as the overall heat-transfer coefficients, gas mass-fraction in the tubing, well depth, and flow rates, in both conduits govern the nonlinearity in temperature profiles. We discuss both synthetic and field examples to illustrate the applicability of the new solution.
Estimation of Permeability From Well Logs Using Resistivity and Saturation Data
Authors: Saner Salih , Kissami Mimoun , Nufaili Subhi Al 
Published: December 2007

Summary
An experimental relationship between permeability, water saturation, and rock resistivity has been suggested. This relationship can be used for interpreting any one of these three parameters when the other two are known. For example, the relationship can be used in interpreting permeability from resistivity logs when water saturation is known. This study is based on electrical measurements of core samples of different permeabilities.
Brine saturation, SW, and corresponding rock resistivity, Rt, were used together to express the permeability of the rock. To eliminate the brine-resistivity effect, the rock resistivity was represented by an apparent formation factor, Fa, which is the ratio of the partially saturated rock resistivity to the brine resistivity, Rw. It was observed that the apparent formation factor vs. water-saturation curves for samples of different permeabilities were arranged similarly to capillary pressure curves, and each permeability is represented by a unique curve. Therefore, permeability was expressed as a function of the apparent formation factor and the brine saturation. When fractional brine saturation is 1.0, permeability becomes a function of formation factor only.
Water saturation and apparent formation factor are the parameters that can be calculated from well logs. When water saturation and apparent formation factor are known, permeability can be estimated from the suggested relationship. Data points from the oil zone, transition zone, or water zone can be used for computations. Permeability determinations are sensitive to the accuracy of water-saturation data near irreducible water saturations, although at high water saturations, accuracy of resistivity measurements becomes more significant for correct permeability results.
Hole-Cleaning Capabilities of Water- and Oil-Based Drilling Fluids: A Comparative Experimental Study
Authors: Hemphill Terry , Larsen T. I. 
Published: December 2007

Summary
Many laboratory studies evaluating the cuttings transport capabilities of water- and oil-based drilling fluids have been published, but few attempts have been made to investigate both fluid types under identical, controlled conditions. Those that considered both fluid types measured cuttings accumulation in the annulus and not fluid velocity. In this comparative study, the efficiency of water- and oilbased muds in cleaning the inclined annulus at varying fluid velocities was investigated. The results showed that, under equivalent rheological and flow-velocity profiles, water- and oil-based drilling fluids clean similarly. While fluid velocity is key to hole cleaning, other parameters, such as mud density and flow index ‘n' factors, can affect cuttings transport efficiency in certain hole angle ranges.
Drilling-Induced Lateral Shifts Along Pre-Existing Fractures: A Common Cause of Drilling Problems
Authors: Maury Vincent , Zurdo Christian 
Published: December 2007

Summary
Two gas well collapses showed a peculiar failure mechanism. Excessive fluid levels and temperature variations during the ultimate drilling phase and later workovers induced microannuli and cementation damage. Abnormal fluid pressures from deeper gas- or water-bearing layers channeled through damaged cementation and increased the pore pressure in uphole faults or bedding joints. Thus the effective normal stress on faults was released, inducing shear displacements and casing deformation. Weakened casings were further collapsed by later fluid-level variations.
It was then suspected that this mechanism also occurred in open holes during drilling. This was shown to be so with borehole televiewer tool (BHTV) images showing borehole lateral shifts. Although never mentioned in the past in the domain of borehole stability, this mechanism explains some poorly understood drilling incidents, such as tight-holes, problems to run in hole (RIH) or pull out of hole (POOH), and abnormal torques, in spite of no indications of instability, such as cavings. This mechanism can be mitigated by taking the necessary precautions during drilling and by the adequate selection of mud characteristics.
Predicting Phase Behavior of Water/Reservoir-Crude Systems With the Association Concept
Authors: Shinta A. A. , Firoozabadi Abbas 
Published: December 2007

Summary
An association model has been incorporated in the Peng-Robinson equation of state (PREOS) to use the combined model for water/res-ervoir crudes phase-behavior calculations. The interaction coefficients between H2O and hydrocarbons follow a simple relationship. Such a relationship makes the use of the association equation of state (AEOS) both accurate and simple. The computed high-pressure crude/steam distillation results by the AEOS are in excellent agreement with the data.