bluuebunny/crossref_metadata_2025_split huggingface dataset:
Offshore Tests of Diamond-Enhanced Rock Bits
Authors: Salesky W. J. , Swinson J. R. , Watson A. O. 
Published: December 2007

Abstract
Maintaining full gage hole while drilling the chert laden Monterey formation offshore California is a constant problem due to the highly abrasive nature of the rock. Three cone rock bits having conventional tungsten carbide gage inserts wear severely necessitating reaming as well as frequent replacement of downhole tools.
Offshore bit tests have been performed on three cone bits with highly wear resistant diamond enhanced gage inserts. These test results have shown these new bits to be capable of drilling in-gage holes through the Monterey formation, and as a consequence, reaming has been significantly reduced.
This paper will give an overview of the drilling problems encountered offshore California. A discussion will be provided on the diamond enhanced insert technology and its impact on drilling performance, downhole tool replacement and reaming time in the Monterey formation offshore California.
An Improved Modeling Program for Computing the Torque and Drag in Directional and Deep Wells
Authors: Ho H. -S. 
Published: December 2007

ABSTRACT
In directional and deep wells, the torque and drag generated by contacts between the drillstring and the borehole play major roles in the following operations of the well: planning, drilling (trouble diagnosis and prevention), and casing running/setting.They also affect the completion/cementing operation.
This paper discusses the shortcomings of the "soft-string" model, which has been widely used in the drilling industry. The soft-string model ignores the effects of drillstring stiffness, stabilizer placement, and borehole clearance. Consequently it generally shows reduced sensitivity to local borehole crookedness and underestimates the torque and drag.
An improved modeling program is presented here that combines a BHA (bottomhole assembly) analysis in the stiff collar section, coupled with an improved soft-string model for the remainder of the drillstring.
Case studies are presented to demonstrate the difference between this improved model and the soft-string model; and also to justify the approach of the improved model.
For deep vertical wells, spiraling of the well can result in very severe torque and drag. Simplified formulas are derived, and examples are given to demonstrate the exponential increases of torque and drag as the well depth increases. In essence, deep vertical wells with spiraling tendencies should be handled as directional wells.
Enhanced Oil Recovery Evaluation of the Flounder T-1.1 Reservoir
Authors: Younes A. M. 
Published: December 2007

ABSTRACT
Under a different and healthier pricing environment, Esso initiated engineering and laboratory work to evaluate a miscible gas process at Flounder. The objective of the evaluation was to study the benefits of immiscible gas injection as well as the potential of achieving miscibility and hence, an incremental oil recovery from the field. To accomplish the project objective, a simulation study and laboratory evaluation of Flounder oil and gas samples were undertaken.
The laboratory studies were necessary to define the miscibility conditions to be expected at Flounder. The simulation study was undertaken to determine if the Flounder reservoir characteristics, such as dip, stratification and permeability contrast, are favourable to achieving higher oil recoveries by gas injection. This paper reviews the results of the simulation and laboratory work which was undertaken at Esso, Exxon Production Research Company and the University of New South Wales.
Transport Mechanisms of Xanthan Biopolymer Solutions in Porous Media
Authors: Kolodziej E. J. 
Published: December 2007

ABSTRACT
The propagation of a polymer slug through porous media is affected by several transport mechanisms including polymer adsorption, inaccessible pore volume, and dispersion. In many previous studies, a specific mechanism (e.g. adsorption) is evaluated, but few studies attempt to evaluate all three mechanisms under a consistent set of flooding conditions. In this paper, a comprehensive study was conducted to evaluate the simultaneous effects of these three mechanisms for single-phase Xanthan biopolymer core floods at 100% brine and at residual oil. The polymer concentration was systematically varied in these floods. The effects of inaccessible pore volume were also investigated in a two-phase Xanthan biopolymer flooding experiment in an initial oil-saturated core. Several key trends on the effects of polymer concentration and residual oil for these polymer transport mechanisms were noted. Attempts are then made to rationalize these trends in terms of microscopic (i.e. molecular and pore level) effects.
Interpretation of High Recovery Obtained in a New Polymer Flood in the Chateaurenard Field
Authors: Putz A. G. , Lecourtier J. M. , Bruckert L. 
Published: December 2007

ABSTRACT
The Courtenay polymer flooding test is being completed, using a larger than usual slug size; a special attention was given to monitoring the concentration and quality of the effluents.
The test is implemented on a ten acres inverted five spot in the center of the field of Courtenay, which is part of the Chateaurenard field. A rather large slug of partially hydrolized Polyacrylamide was injected, consisting of 42% pore volume of a 1000 ppm active polymer concentration solution followed by a 39% pore volume solution at a tapered concentration.
By matching the oil cuts and polymer concentrations in the effluents of the producing wells we estimate that the adsorption of the polymer on the rock was 35 μg/g of rock.
Concentrations and main characteristics of produced polymer at the wellhead were determined using a sampling and separation methodology which prevents chemical and mechanical degradation. An increase in polymer molecular weight versus time has been observed, this polymer is not harmed by flow in the reservoir.
Performance Update of a Dual-Resistivity MWD Tool with Some Promising Results in Oil-Based Mud Applications
Authors: Grupping T. I. F. , Harrell J. W. , Dickinson R. T. 
Published: December 2007

ABSTRACT
A new "Toroidal" Measurement While Drilling (MWD) resistivity tool was introduced to the oil and gas industry in 1986. The tool utilises the drill collar as an electrode to provide two independent resistivity measurements: a focused lateral resistivity measurement and a trend resistivity at the drill bit. In oil based muds the tool provides a single high-resolution measurement at the bit-to-formation contact.
Since its introduction the tool has been operated in a variety of diverse drilling environments, both in the North Sea and in North America, and in a wide range of drilling fluids including oil based muds.
This paper reviews the performance of the tool with specific log examples highlighting the qualitative and quantitative responses of both resistivity measurements in comparison to conventional wireline logs. Particular attention is also given to the advantages and limitations of logging in the MWD environment.
As a result of these operating experiences several changes were necessary in order to improve the reliability of the tool and to ensure good log quality, especially in fast drilling formations. These problems together with the effected solutions will also be presented.
Finally a brief review will be made of future enhancements to MWD systems which will provide additional sensors for formation evaluation and reservoir analysis.
Fracture Detection in Low-Permeability Reservoir Sandstone: A Comparison of BHTV and FMS Logs to Core
Authors: Laubach S. E. , Baumgardner R. W. , Monson E. R. , Hunt E. , Meador K. J. 
Published: December 2007

ABSTRACT
Detection and characterization of fractures in low-permeability reservoirs is an important goal of reservoir analysis. Natural fractures may increase porosity in low-permeability rock and may enhance or limit the success of hydraulic fracture treatment. Two logging tools used for fracture detection are the borehole televiewer (BHTV), an acoustic device that maps the smoothness of the borehole wall, and the Formation Microscanner (FMS*), a resistivity tool that produces a conductivity map of two 2.8-inch-wide strips of the borehole wall. Our analysis compares BHTV and FMS logs to 1,028 ft of core from three wells in the 2,000-ft-thick Lower Cretaceous Travis Peak Formation, a sandstone and shale unit that produces gas from low-permeability sandstone in East Texas. Core was obtained from depths of 5,900 to 9,900 ft. The Travis Peak provides a good test of fracture-imaging logs because natural fractures have complex geometry and variable mineral fill and because there are borehole breakouts, drilling-induced fractures, and vertical sedimentary structures that must be distinguished from natural fractures for successful fracture analysis.
Vertical extension fractures in Travis Peak sandstone usually are visible on BHTV and FMS logs, but some fractures were missed by FMS pads. Low-angle natural shear fractures observed in core were not seen on either log. Both BHTV and FMS represent fracture shape and distinguish fractures from borehole breakouts. FMS gives a high-resolution image of fracture shape, but natural fractures could not be distinguished from drilling-induced fractures on either log. Existing commercial BHTV and FMS techniques do not give a quantitative measure of fracture aperture. Fracture orientation is readily obtained for inclined fractures from either BHTV or FMS logs, but the orientation of vertical fractures is commonly ambiguous on both logs. These results show that BHTV and FMS logs are useful adjuncts to core-based fracture studies for evaluation of fractured reservoirs.
Similarities and Differences in Methods Currently Used to Analyze Pressure-Transient Data from Layered Reservoirs
Authors: Larsen Leif 
Published: December 2007

SUMMARY
Methods currently used to analyze pressure-transient data from layered reservoirs are investigated, and similarities and differences highlighted with emphasis on the mathemats behind the various methods. All of the basic mathematical models for single-phase flow of slightly compressible fluids in layered reservoirs are considered, allowing layers to have only horizontal flow, only vertical flow, or flow in both directions in the basic model, and allowing both uniform and mixed boundary conditions.
Generation of type curves for standard analyses and generation of synthetic data for use in history-matching procedures are considered the most important applications of the results of the paper. The results are, however, also used to show that some aspects of the characteristic behavior reported in the literature for layered reservoirs are caused by the mathematical modelling and not by reservoir layering.
Improving Prudhoe Bay Pulse-Test Data by Processing with Fourier Transforms
Authors: Bradley D. A. , Allen T. T. 
Published: December 2007

Abstract
Pulse testing using surface-pressure measurement has proven to be a cost-effective way to establish reservoir continuity and to determine interwell reservoir properties at Prudhoe Bay. Using portable surface measurement equipment – instead of wireline-conveyed bottom-hole measurement tools – at the observation wells has significantly reduced the cost of conducting the tests. However, the pulse test analysis is often complicated by extraneous pressure fluctuations in the surface-measured data. These fluctuations may be caused by variations in ambient temperature, by operation of surface production equipment, or by reservoir pressure transients generated by offset wells. To eliminate these detrimental effects, a method has been developed which uses Fourier transforms to process the surface data. Once the data has been processed, conventional analysis of the pulse-test data can be improved substantially. This paper discusses the method, as well as its application to two Prudhoe Bay pulse tests.
A Rule-Based Approach to Dipmeter Processing
Authors: Kerzner M. G. 
Published: December 2007

ABSTRACT
A new algorithm for dipmeter processing is being described. This work is a continuation of the work described in a previous paper1, however, to achieve improved performance, major changes were introduced, both in the theory and in realization of the algorithm. The central idea of the new work is the formulation of a number of rules of visual correlation. These rules are then applied in attempts to find acceptable correlations. The sequence of the application of the rules is dependent upon the character of the data, and the process continues until a good correlation is found. In contrast, in previous work, there were fewer rules, and all of them were applied together in a general optimization scheme. This new approach gives the program additional flexibility, which lets it process data that could not be handled previously, and also results in a much more practical running time. Another advantage of the new algorithm is the possibility of a number of options in the level of detail of the dip analysis — from very general to very fine.
Electrolytic Conduction in Partially Saturated Shaly Formations
Authors: Schwartz L. M. , Sen P. N. 
Published: December 2007

Abstract
An essential feature of electrical conduction in shaly sands is the fact that the surface and bulk tortuosities are not identical as assumed in most empirical models. For an arbitrary geometry of insulating, but charged, objects immersed in an electrolyte for which diffusion currents are important, the DC electrical conductivity problem can be mapped into a superposition of two ordinary conduction problems without diffusion currents but with conductive surface layers. We apply this mapping to a generalization of the grain consolidation model in which a shaly sand is modelled by a three dimensional periodic array of charged overlapping spherical grains. We solve numerically for the electrical conductivity, σ, as a function of the porosity ϕ, brine salinity σw, charge density Qv, and water saturation Sw. The results of these calculations provide a basis for new empirical saturation equations which can be used in exploration geophysics.
Interference Test in a Fractured Carbonate: A Lisburne Case History
Authors: Sampson L. E. , Marcou J. A. 
Published: December 2007

ABSTRACT
A case history is presented for a 160-acre-five-spot interference test performed in the Wahoo formation, a fractured carbonate within the Lisburne reservoir located at the North Slope of Alaska. Several results are realized from this test. First, the Lisburne reservoir is a heterogeneous formation with the possibility for dual porosity and multi-layered behavior. Second, interference pressure data from two of the four observation wells can be analyzed utilizing a modified approach to the conventional anisotropic permeability technique. Third, even with considerable pre-test planning and design, the reservoir responded differently than expected.
The Lisburne Interference Test preceded field startup in an effort to determine directional permeability and to evaluate vertical and lateral continuity within the reservoir with a rninimum amount of offset interference. The center well was cycled through a drawdown and build up while the four corner wells monitored pressure. Bottomhole pressure recorders were installed in the wellbores prior to the start of the test. During the interference test, the observed pressure responses in the observation wells were significantly more rapid and of a greater magnitude than expected. Concurrent pressure transient analysis of the data, made possible by surface readout equipment, resulted in a shorter, less expensive test.
The test analysis provided effective reservoir permeability from dual porosity type curve matching and semi-log analysis of the active well data with good agreement between the drawdown and build up results. Analysis of the observation well pressure data was consistent with the active well data and was achieved using dual porosity transient interporosity flow type curves and semi-log analysis.
Because of reservoir heterogenities, the pressure data from only two of the four observation wells were analyzable with the conventional anisotropic permeability analysis method. Generally this method requires pressure data from three uniquely-oriented observation wells to obtain a solution. However, the anisotropic permeability model can place limits on the feasible solutions using data from only two wells, and with the elimination of one of the four unknown values through core data, a complete solution of the Lisburne Interference Test was achieved.
Falloff Testing a Waterflood-lnduced Fractured Well in Western Venezuela
Authors: Prado L. R. , van Kruysdijk C. , Niko H. , Sancevic Z. A. , Rodríguez R. 
Published: December 2007

ABSTRACT
A high-precision fall-off test, carried out by Maraven in the water injection well VLA-440w in western Venezuela with the objective of determining the length of a waterflood induced fracture, has been analysed using the latest interpretation tools available. Deconvolution techniques were used to remove the effects of storage on the pressure data, thus enabling the identification of the characteristic flow regimes for a fractured well. In addition, the use of the pressure derivative plot enabled the characterisation of the flow system which led to a type-curve match of the data as the only way to interpret the test. Using a recently developed semi-analytical model, a type curve match was obtained with the response of a fractured well with fracture wall skin effect.
The presence of a skin on the fracture wall in fact extends the duration of the fracture linear flow period which allowed us to observe this period in the data. An effective permeability of 2 mD, a fracture half-length of 900 ft and a skin of 0.15 were obtained from the type-curve match. Moreover, the formation permeability calculated is in agreement with available petrophysical information. In addition, a short injectivity test performed after the fall-off qualitatively confirmed the interpretation.
Facies Modeling and the Flow Unit Concept as a Sedimentological Tool in Reservoir Description: A Case Study
Authors: Rodriguez A. 
Published: December 2007

ABSTRACT
Early recognition of porosity and permeability contrast in a reservoir has economic implications in reservoir management. Correct reservoir heterogeneity description is the key for such recognition. Problems such as number of blocks to be used in simulation modelling can be minimized with a proper understanding of the reservoir. Several techniques, including "slice-technique," "fining and coarsening-upwards" sequences, and lithological transgressive/regressive concepts, have been used for reservoir description.
With the advance in facies modelling, sedimentological studies have introduced facies-zones, and facies associations as flow units for reservoir sublayering. But, in the literature, there is a lack of objective parameters with which to place boundaries between adjacent production intervals. The objective of this paper, therefore, is to present a methodology which allows subdivision of a sedimentary column, for reservoir description, based on quantifiable rock characteristics.
The study of the cored section of the Eocene C Reservoir, Block III, lake Maracaibo, allowed facies characterization with physical, chemical, and biological parameters. By identifiying major changes in the related depositional sequences, facies units were characterized with porosity and permeability values. The so defined intervals were proven valid by histograms and cross-plots obtained from the petrophysical data. Biostratigraphic analysis also support this subdivision.
Since the combination of sedimentological, petrophysical and biostratigraphic characteristics support a similar sublayering of the cored sedimentary section, the Sedimentary Units were taken as representative of main flow units. Facies maps constructed for each Unit, show a sequential deltaic development with different sand geometries.
Results obtained with this facies approach show that by combining independent 1ines of evidence it is possible to have an objective and quantifiable methodology for reservoir heterogeneity description. A scientific tool for minimizing number of blocks to be utilized in simulation studies is given by grouping of facies with similar permeability characteristics within a well defined Flow Unit.
Reliability of Anelastic Strain Recovery Estimates for Stress Orientation in the Travis Peak Formation, Harrison County, Texas
Authors: Owen L. B. , Toronto T. W. , Peterson R. E. 
Published: December 2007

ABSTRACT
The Gas Research Institute sponsored a series of Staged Field Experiments (SFE) which collectively provided an important opportunity for critical evaluation of various methods for prediction of hydraulic fracture orientation. During the period August-September, 1986, the SFE No. 1 well was drilled in the Waskom Field, Harrison County, Texas. This well penetrated the Travis Peak Formation of Lower Cretaceous age. Core recovery was 471 ft of which 91.4 ft was oriented. Eight methods were employed for the determination of in-situ stress orientation: Orientation of Natural Fractures and MicrofracturesOrientation of Fluid Inclusion PlanesOrientation of Coring Induced Centerline and Petal FracturesOrientation of Stress Test FracturesBorehole Ellipticity3-D Microseismic SurveysDifferential Strain AnalysisAnelastic Strain Recovery
Orientation of natural fractures by petrography, borehole televiewer and formation microscanner resolved a primary fracture with an azimuth between 70-80 deg. Subsidiary fractures were observed at 90-100 deg and 120-130 deg. Minor features were found at 35-45 deg and 145-165 deg. The orientation of fluid inclusion planes was more scattered but of similar character, coring induced fractures observed in recovered oriented core were generally coincident with the observed natural fracture pattern.
Four stress tests performed during the coring operation provided evidence for a preferred fracturing direction at 76 ± 8 deg. The orientation of a treatment-induced fracture at a depth of 6410 ft was mapped by a microseismic survey at 69 deg. Average well bore ellipticity was 68 deg. One differential strain analysis for a mudstone yielded a maximum horizontal stress orientation of 90 ± 20 deg.
Horizontal strain recovery data were successfully obtained for 18 samples during the coring operation. Core orientation data were available for 11 of the analyzed samples. Each sample was approximately 6 inches in length. Tested litholo-gies included sandstones, mudstones, shales and siltstones. The quality of strain recovery data was excellent in most cases. Calculated orientations for maximum horizontal stress direction fell into three groups. Three samples yielded an orientation of 69 ± 10 deg. Seven samples yielded an average orientation of 116 ± 10 deg. One sample indicated an orientation of 28 deg. The average orientation of the maximum horizontal stress (excluding the 28 deg sample) was 102 ± 24 deg.