bluuebunny/crossref_metadata_2025_split huggingface dataset:
Automated Fracture Detection on High Resolution Resistivity Borehole Imagery
Authors: Ye Shin-Ju , Baviller Philippe 
Published: December 2007

Abstract
This paper proposes a method to detect fractures on High Resolution Resistivity Borehole Imagery. The method provides with quantitative parameters, such as length and contrast of the fractures that can be processed with conventional logs to help characterize reservoir nature and behavior.
Thanks to the auto-optimization of the algorithm, this method is easy to operate, does not require expertise and can be used in drilling operation, on the site, in the meantime between log acquisition and casing perforation.
The method takes advantage of the fact that:–fractures are planar features secant to the stratification planes and exhibit high resistivity contrast.–stratification planes represents the dominant orientation of planar features that are seen on HR resistivity borehole imagery and, based on this characteristic, they can be detected using statistical analysis of the full image (The method is described on SPWLA logging Symposium transactions 1997, paper O).
After detection of the stratification planes, images are processed to filter out the stratification planes and normalize the background, thus making more visible the fracture planes. Fractures segments are detected on each "pad" images using "depth-first search" algorithm to find "min-cost path" and then selected according to length, contrast, linearity and visibility criteria. An image displaying the fracture segments and the associated quantitative parameters is produced. Detailed field examples are used to illustrate the results obtained in different types of lithology.
P. 777
Dynamic Displacement Measurement of Three-Phase Relative Permeabilities in Berea Sandstone Cores
Authors: Siddiqui Shameem , Yang Jiansui , Ahmed Mahbub 
Published: December 2007

Abstract
The measurement of three-phase relative is often a difficult and time-consuming process. To this date only a handful of papers can be found in the literature on the measurement of three-phase relative permeabilities. Grader and O'Meara developed an unsteady-state technique for measuring three- phase relative permeabilities by extending the Buckley Leverett theory to three phases. The validity of this new unsteady-state technique has been verified recently for three immiscible liquids in a glass-bead pack with the help of a medical CT-scanner (Siddiqui and Siddiqui et al.) However, this new technique has not been applied to measure the three- phase permeabilities of a rock -fluid system similar to that of a typical petroleum reservoir. This present study focuses on the application of the extension of the Buckley-Leverett theory for measurement of three-phase relative permeabilities for a brine- oil-gas system in Berea sandstone cores (permeability range 100-400 md). Several experiments were conducted using a specially designed coreflooding unit in which pressure at six locations along the core and flow rates are recorded continuously with a computerized data acquisition system. The three-phase flowpath used for this study was dynamic gas injection into the cores having a different initial water and oil saturation each time. Three-phase relative permeability data derived this way were used in a simulator to predict the recovery curves. Results show a good agreement for the different cases studied. Comparison is also made between these data and the data from experiments done with three immiscible phases (Siddiqui).
P. 759
Detection of Critical Flow Leaks in Deepwater Gas Flowlines
Authors: Scott Stuart L. , Yi Jinghai 
Published: December 2007

Abstract
Detection of hydrocarbon leaks from deepwater subsea flowlines represents a special challenge to both the oil and gas industry and regulators. The lack of inlet flow rate measurements, combined with an order-of-magnitude increase in gas solubility, limited access, ultra high flowrates and deepwater currents, is anticipated to compel new testing, inspection and monitoring methods for deepwater flowlines. This paper presents a leak detection technique based on routine production data, i.e. inlet and outlet pressure and outlet flow rate. This method is particularly valuable when inlet flow rate measurements are either unavailable or are of low accuracy. Based on the gas well backpressure technique, the proposed method detects changes in pipeline frictional losses resulting from a leak. Field-scale verification of the proposed method was obtained using the LSU 9,460 ft. horizontal flowloop made of 4 1/2 inch drillpipe. Multi-rate tests were conducted using methane at 650 psig with fixed diameter leaks of 1/8, 1/4 and 3/8 inches placed at the midpoint of the flowloop. The proposed method is shown to be effective in detecting leaks and, while location of the leak is also possible, it will likely require a large number of rate/pressure points to be useful. Based on this method a map has been developed that indicates what size of leak is detectable for a given set of field instruments and flow conditions.
P. 793
More Than 12 Years of Experience with a Successful Conformance-Control Polymer Gel Technology
Authors: Sydansk R.D. , Southwell G.P. 
Published: December 2007

Abstract
In this paper, we discuss and describe our extensive experience with the widely applied and quite successful Cr(III)-carboxylate/acrylamide-polymer (CC/AP) gel technology for use in oilfield conformance-control, sweep-improvement, and fluid-shutoff treatments, along with briefly reviewing the gel technology's development. Chromic triacetate is the often- preferred chemical crosslinking agent used in conjunction with this polymer-gel technology. The CC/AP gel technology, which was conceived in late 1984, is characterized as having a robust gel chemistry and as being highly insensitive to petroleum reservoir environments and interferences. This gel technology has been employed in over 1,400 conformance- control treatments worldwide. Highlights of illustrative field applications and results involving the CC/AP conformance- control gel technology are presented. An overview of what a decade-plus of experience in developing and applying the CC/AP gel technology has taught us is discussed. This includes discussion of: classifying and distinguishing conformance problems and treatments, attributes of good candidate wells and well patterns for gel conformance-control treatments, requirements that must be met in candidate wells and well patterns in order to achieve success, gel treatment elements that must be successfully implemented in order to achieve success, guidelines where conformance polymer-gel treatments are most successfully applied, risks and pitfalls of gel conformance treatments, and quality control issues.
P. 841
Phase Diagram of fully Developed Drainage: A Study of the Validity of the Buckley-Leverett Equation
Authors: Yortsos Yannis C. , Xu Baomin , Salin Dominique 
Published: December 2007

Abstract
Despite the significant progress made in recent years, a fundamental understanding of immiscible displacements at the macroscale is lacking. In this paper we use a version of percolation theory, based on Invasion Percolation in a Gradient, to connect drainage processes at the pore-network scale with the displacement at the macroscale. When the mobility ratio M is sufficiently small, the displacement is stabilized and can be described by Invasion Percolation in a Stabilizing Gradient. In the opposite case, the displacement has common features with Invasion Percolation in a Destabilizing Gradient. A phase diagram of fully developed drainage is then developed. The transition between stabilized displacement and fingering is controlled by the change of the sign of the gradient of the percolation probability, and the transition boundary is described by a scaling law involving the capillary number and the viscosity ratio. The theory is subsequently extended to correlated pore networks and a phase diagram involving the correlation length A is constructed. As the regimes of stabilized displacement are also those for which conventional theories (such as the Buckley-Leverett equation) apply, the phase diagram helps to delineate their validity.
P. 877
Implementation of Multirate Technique to Measure Relative Permeabilities Accounting
Authors: Virnovsky G.A. , Vatne K.O. , SkjaeveLand S.M. , Lohne A. 
Published: December 2007

Abstract
A practical implementation of the multi-rate steady-state technique to determine relative permeabilities from steady- state floods and its comparison with the standard steady-state technique is the main subject of the paper. The multi-rate technique is based on the theory of two-phase flow, and facilitates analytical corrections of relative permeabilities to account for capillary end effect. This is especially of practical importance if the experiment is performed at low rates when the relative role of capillary forces increases.
Normally, it is recommended to perform flooding experiments at high rates and/or on long cores to suppress capillary effects. Though this approach ensures simplicity in the interpretation procedure it disregards several factors one of which is that the relative permeabilities may depend on the rate. Proper account for capillary effects makes usage of long cores and high rates unnecessary.
A number of steady-state core floods have been performed at different rates varying from a high rate typically used in the lab experiments to a low rate approaching the range of typical reservoir rates. The experimental results, i.e. a set of relative permeabilities depending on the rate, have been interpreted both without and with account for capillary end effect. The previously developed analytical corrections for capillary effects were implemented in the interpretation. The results of analytical interpretation are quality controlled by numerical simulation of the experiments. It is shown that much of the difference observed in relative permeability curves and residual saturations measured at different rates can be explained by the influence of capillary end effect.
P. 901
Quantification of Vuggy Porosity in a Dolomite Reservoir from Borehole Images and Core, Dagger Draw Field, New Mexico
Authors: Hurley N. F. , Zimmermann R. A. , Pantoja D. 
Published: December 2007

Abstract
Vugs, which are large irregular pores, are a key pore type in many carbonate reservoirs. Because of coarse sample rate and limited vertical resolution, conventional wireline logs commonly mask vuggy porosity. This becomes a major problem when logging tools combine high vuggy porosity with low matrix porosity to derive average porosity values that fall below arbitrary commercial cutoffs. Non-completion of such zones commonly results in bypassed pay.
Borehole-imaging logs are high-resolution, oriented electronic "pictures" of the wellbore made by electrical or acoustic devices. Pixel-counting techniques, when applied to borehole images, can be used to detect and quantify vugs. The purpose of this study is to calibrate vugs quantified from borehole images to those quantified from digitally scanned core. Samples studied are vuggy dolomites of the Cisco and Canyon Formations (Pennsylvanian), Dagger Draw field, Eddy County, New Mexico. Results suggest that the neutron log is a good total-porosity device. However, this log suppresses the evidence for vuggy porosity which can lead to bypassed pay.
Determination of Oil/Water Saturation Functions of Chalk Core Plugs from Two-Phase Flow Experiments
Authors: Bech N. , Olsen Dan , Nielsen C. M. 
Published: December 2007

Abstract
A new procedure for obtaining saturation functions, i.e. capillary pressure and relative permeability, of tight core samples uses the pronounced end effect present in flooding experiments on such material. Commonly being a nuisance in core analysis, the end effect contains valuable information about the saturation functions. In core material with high capillary pressure, the end effect may allow determination of the saturation functions for a broad saturation interval. A complex core flooding scheme provides the fluid distributions and production data from which the saturation functions are computed by a least squares technique. An NMR technique is used for fluid distribution determination. The steady state situation at the end of a primary drainage experiment allows calculation of the drainage capillary pressure and the drainage relative oil permeability. The relative water permeability is calculated from the unsteady state data obtained during the transient part of this experiment. After a flow reversal, a new end effect develops at the opposite end of the core by an internal imbibition process, which at steady state allows calculation of the spontaneous imbibition capillary pressure and the imbibition relative oil permeability. Following a change from oil flooding to water flooding, the forced imbibition capillary pressure is calculated from transient pressure drop measurements. An undesirable interdependency of the saturation functions is avoided by their calculation from different data sets. Killough's method is employed to account for the scanning effect in hysteresis situations for both capillary pressure and relative permeability. The scanning parameter is determined as well. The procedure is demonstrated on chalk samples from the North Sea. The experimental time is intermediate between the centrifuge and porous plate methods. The procedure is superior to the centrifuge and mercury injection methods respectively by eliminating errors from end effects and using reservoir relevant fluids.
Revealing the Petrophysical Properties of a Thin-Bedded Rock in a Norwegian Sea Reservoir by the Use of Logs, Core, and Miniperm Data
Authors: Flolo Lars Helge , Menard Wendell P. , Weissenburger Ken W. , Kjaerefjord Jostein M. , Arnesen Dag M. 
Published: December 2007

Abstract
An unconventional thin-bed analysis based on logs, core and miniperm data was needed to calculate the petrophysical properties of a reservoir under development in the Norwegian Sea. More than half of the reservoir section under investigation is composed of heterolithic facies: thinly interbedded sandstone and mudstone layers from one to several centimeters in thickness and of variable quality. By using miniperm measurements with 1-cm spacing on slabbed core, it was possible to resolve the properties of the rock far below the vertical resolution of conventional wireline logs and relate them to the bulk log measurements,
P. 815
Geological Framework Modeling and Rock Type Optimization for a Giant Oil Field, Offshore Abu Dhabi
Authors: Neo Sadafumi , Asada Jiro , Fujita Nozomi , Mohammed Salman , Arab Hani 
Published: December 2007

Abstract
Reservoir characterization study was conducted to build a realistic 3D flow unit model for Thamama II carbonate reservoir by clarifying geological factors controlling highly heterogeneous permeability distribution in this reservoir.
Algal micritization was found as a key geological factor of this reservoir leading to both rock type optimization and geological framework modeling. Petrophysically, algal micritization alters grain type and pore type thoroughly by creating abundant micro-pores within grains and closing intergranular macro-pores due to easy compaction of softened grains. In terms of distribution, such algal micritization is significant mainly in a shallow shoal area according to recent carbonate analogue from offshore Abu Dhabi. A total of 10 lithofacies was defined based mainly on the composition of newly defined 8 grain types, which represent distinct micro-pore distribution, physical property and depositional environment.
Pore throat size distribution curve analysis shows that peak pore throat size from SCAL data fairly matches with calculated pore throat size using Winland equation. Petrographical and petrophysical evaluation led to fair to good poro-perm regression to a Flow Zone Indicator (FZI) curve for each lithofacies, which is reasonably explained by a unique composition of different pore types in each lithofacies. These lithofacies were further grouped into 6 rock types by FZI value.
Areal distribution of these lithofacies shows aggradational stacking pattern and abrupt lateral change particularly in Lower IIB-IID. This rather matches with detached rimmed carbonate shelf model controlled by a NW-SE trending shoal and tidal channel system, contrary to the conventional understanding of progradational carbonate ramp model for this reservoir. Two high permeability lithofacies composed of non-micritized grains and intergranular pores were recognized lying along tidal channels.
Permeability maps were preliminarily generated for key layers using lithofacies/rock type maps, unique FZI value for lithofacies/rock type and log porosity. Further optimization of rock type with relatively poor FZI regression is planned in the next phase to accomplish better match among predicted permeability, core permeability and dynamic data.
A Geostatistical Approach to Attribute Interpolation Using Facies Templates, an Advanced Technique in Reservoir Characterization
Authors: Alqassab Hisham M. , Heine Christian J. 
Published: December 2007

Abstract
Reservoir characterization is considered a crucial step for fluid flow simulation studies. The need for quantitative, detailed and sound geocellular models that can simulate the effect of reservoir heterogeneity has become increasingly important in recent years.
This paper focuses on a geostatistical approach, using geology and seismic derived templates from an eolian depositional environment to produce a high resolution 3-D geocellular model.
Hawtah-Field of Central Arabia, which demonstrates an eolian environment of deposition, is used as an example. Two facies are present with different facies distributions, namely a high quality reservoir dune facies which has a dominant east transport direction and a non-reservoir inerdune facies which has an isotropic distribution. Directional variograms are used to capture both trends and continuity of each facies within defined stratigraphic sequences.
Directional variograms are then used in building 3D facies models using indicator algorithms utilizing log-derived facies and geological templates for each of the thirteen stratigraphic sequences. The geological templates, based on borehole image and seismic amplitude data, are used to derive varying azimuth and anisotropy which variograms can't accomplish alone.
Finally, sequential gaussian simulation is selected to construct a quantitative, high-resolution reservoir model of porosity and permeability based on facies. These models will honor data at the wells in addition to maintaining facies variations observed in the interwell vicinity constrained by geological templates. These models will then be ready for fluid flow simulation and ultimately for reservoir performance predictions upon which to base reservoir management decisions.
Integrated Reservoir Characterisation of a Giant Lower Cretaceous Oil Field, Abu Dhabi, U.A.E.
Authors: Jürgen Grötsch , Omar Al-Jelani , Yousif Al-Mehairi 
Published: December 2007

Abstract
In the framework of the integrated reservoir characterization study (IRCS) for a giant Lower Cretaceous oil field in Abu Dhabi, a key deliverable was a sedimentological and diagenetic model of the field to be used as input for 3-D geological modeling of the stacked reservoir zones. Integrated 3-D reservoir characterization in carbonate fields is a topic of ongoing discussion whereby data preparation, data requirements, as well as actual static and dynamic modeling procedures vary considerably in the industry, in general, and from field to field, in particular. One of the more often raised issues is the link between bio-facies based models incorporating depositional and sequence stratigraphic characteristics and their link to the 3-D petrophysical property distribution. In this paper, the concept of reservoir rock type based modeling is introduced as a missing link between static and dynamic modeling. Such rock-type based 3-D models can equally provide vital input for further seismic and geo-mechanical modeling.
Optimization of Well Completion in Water Flooding Pattern Using Flexible Grid Simulator
Authors: Takahashi Shunya , Kuwauchi Yusuke , Yamazaki Noboru 
Published: December 2007

Abstract
This paper described a simulation case study on an infill well in a water flooding pattern. A 3-Phase, 3-Dimensional • flexible grid simulator, namely VERDI-3D which was developed by Technical Research Center of Japan National Oil Corporation, was used to study the oil recovery performance for various well completions and optimize the direction of lateral hole. The study assumed an actual carbonate reservoir in Middle East having heterogeneous characteristics. In a history matching phase, simulation was conducted using a combined grid system i.e. radial grids around vertical wells and Cartesian grids as a background. In a prediction phase, flexible grids were newly defined and superimposed over the original grid system according to the type and trajectory of the infill well. The variable parameters such as pressure and water saturation values were reallocated for the new grid system. Then the model was restarted to predict the well performances. Same case study was conducted using a commercial simulator ECLIPSE and the results were compared with those of the VERDI-3D. Based on this case study, the applicability of VERDI-3D to actual field problem was confirmed.
Short Term Analysis of Wells with Finite Conductivity Fractures Using Simultaneously Measured Transient Pressure and Flow Rate
Authors: Almehaideb R. A. , Abou-Kassem J. H. , Osman Mohammed E. 
Published: December 2007

Abstract
Analyses of variable flow rate tests have been given special attention recently because it is generally impractical to keep a constant flow rate long enough in the field to perform a drawdown test. Also, in many other situations, the early time data are usually affected by wellbore storage. For fractured wells, this early time period represents linear or bilinear flow in fractures. Thus, it is very important to devise a technique that would allow a petroleum engineer to obtain reservoir in addition to fracture characteristics such as fracture conductivity and fracture half-length, using this early flow data.
In this paper, a new mathematical model is developed to describe drawdown and buildup tests for wells intersected by finite conductivity fractures. This new model utilizes the convolution method to arrive at a solution for downhole pressure versus time using simultaneously measured downhole pressure and sandface rates. Analysis based on the solution of this new model allows one to calculate directly both reservoir and fracture characteristics. Results obtained are verified by solving two field examples to demonstrate the model capabilities. A step by step procedure for analysis is also presented.