bluuebunny/crossref_metadata_2025_split huggingface dataset:
Production-Induced Compaction of the Brent Field: An Experimental Approach
Authors: Schutjens P. M. T. M. , de Ruig H. , Sayers C. M. , van Munster J. G. , Whitworth J. L. 
Published: December 2007

Summary
The most attractive option to increase hydrocarbon recovery from the Brent and Statfjord reservoirs (Brent field, North Sea) is a gradual decrease of the reservoir fluid pressure. To provide laboratory data upon which estimates of the resulting reservoir compaction and surface subsidence could be made, we performed uniaxial compaction experiments at room temperature and in-situ stress conditions. Experimental observations suggest that the reloading of core samples to in-situ stress conditions closed coring-induced microcracks. Most Brent samples (porosity 6% to 30%) showed a compressibility that was constant with increasing effective stress (i.e., linear compaction) and increased with porosity. There was 30% to 75% strain recovery during unloading and an average permanent shortening of about 0.7%. Some high-porosity (25% to 30%) Brent samples showed a relatively high uniaxial compressibility that increased with stress (nonlinear compaction). Nearly all the Statfjord samples showed nonlinear compaction. The Statfjord samples from Core A, with a porosity of 8% and 20% to 22%, showed about 45% strain recovery upon unloading and an average permanent shortening of 0.6%. The Statfjord samples from Core B (porosity 22% to 28%) showed only 24% strain recovery and an average permanent shortening of 3.2%. Microscopy analysis of the Brent samples revealed no evidence for a compaction-induced change in microstructure. In contrast, the Statfjord samples from Core B (22% to 28% porosity) displayed numerous intergranular and transgranular cracks in quartz and feldspar grains, which probably triggered grain sliding and grain rotation. These inelastic brittle mechanisms, which occur together with elastic deformation of the load-bearing grain framework, seem dominant in high-porosity (Statfjord-type) sandstones and should be incorporated into predictive models of production-induced compaction of quartz-rich reservoir rock.
Deconvolution Under Normalized Autocorrelation Constraints
Authors: Baygün B. , Kuchuk F. J. , Arikan O. 
Published: December 2007

Abstract
In this paper we describe a time domain algorithm for determining the influence function from the measured input and output signals of the system. The deconvolution, which is a highly unstable inverse problem with measurement errors, is an important step for obtaining the system's influence function that provides insight about flow regimes normally masked by the time-dependent input signal. The algorithms presented for deconvolution in the literature are generally based on data reduction, with the exception of constrained deconvolution methods.
We propose a constrained least-squares deconvolution method to reconstruct the influence function from noisy data. The constraints are the lower bounds on the first few lags of the normalized autocorrelation coefficients of the influence function. The lower bounds may represent known or desirable smoothness properties of the function. By choosing the constraint values larger, a smoother deconvolution can be obtained. We also impose an energy constraint on the derivative of the reconstructed signal for further regularization.
Invasion Profiling With a Multiple-Depth-of-Investigation Electromagnetic-Wave Resistivity Sensor
Authors: Bittar M. S. , Rodney P. F. , Hendricks W. E. 
Published: December 2007

Summary
The EWR-Phase 4SM sensor is the first measurement-while-drilling (MWD) electromagnetic resistivity tool to offer multiple depths of investigation by use of measurements made from signals originating at different distances from the receivers. As a propagating-wave resistivity device, it measures four phase shifts and four attenuations. This yields eight different apparent depths of investigation, allowing more meaningful information about the invasion profile.
With the phase-shift measurements alone, the traditional three-parameter step invasion model can be used to obtain the virgin formation resistivity, Rt; the flushed zone resistivity, RXO; and the diameter of invasion, Di. These same four measurements can also be interpreted with a ramp invasion model, a sloped-transition invasion model, and a continuous-monotonic invasion model. For more complex invasion profiles, such as an annular invasion profile, all eight measurements can be used to describe the invasion profile accurately.
Invasion profiling starts with an examination of the trends among measurements. These trends are used to select one or more invasion model(s) to use in the interpretation (step, ramp, sloped transition, continuous monotonic, or annulus). Once the form of a model has been selected, the model parameters are computed by use of a modified Levenberg-Marquardt algorithm, which minimizes the sum of the squares of the differences between the measured and reconstructed resistivities. Examples are presented that compare the results of interpreting invasion following one of the previously stated invasion profiles with one of the others as a reference model. Guidelines on the use of these models are given. Finally, some field examples are analyzed and presented.
EM Log Response to Anisotropic Resistivity in Thinly Laminated Formations With Emphasis on 2-MHz Resistivity Devices
Authors: Hagiwara Teruhiko 
Published: December 2007

SummaryAnisotropic resistivity is not uncommon in electromagnetic logging environments. Many shale formations are known to be anisotropic. Thinly laminated sand/shale sequences behave as macroscopically anisotropic formations.We analyzed the tool response to anisotropic resistivity for each type of EM logging tool: electric resistivity logs, induction type logs, and toroidal resistivity tools.In particular, the effect of anisotropy on the logging-while-drilling 2-MHz induction-type resistivity log is discussed in detail. The effect causes differences between phase-derived and attenuation-derived apparent resistivities, between apparent resistivities from different transmitter-receiver spacings, and between apparent resistivities measured at different operating frequencies. Based on the tool response analysis, we present a method to estimate anisotropy from log data. An application to laminated sand analysis is discussed, in which the sand lamina resistivity and the net-gross ratio (N/G) are determined simultaneously.
A Technique for Faster Pulse-Decay Permeability Measurements in Tight Rocks
Authors: Jones S. C. 
Published: December 2007

Summary
Laboratory pulse-decay measurements using a gas or liquid are effective for determining the permeability of rocks in the range from 0.1 md to 0.01 μd. The actual measurement time with this pressure-transient technique is fairly short, but pressure pre-equilibration sometimes requires hours. This paper shows how the total time can be reduced significantly, especially if the sample's pore volume (PV) is measured independently or estimated accurately. Permeability is calculated from "late-time" measurements. Strategies for minimizing errors and increasing sample throughput are presented.
Physical and Numerical Modeling of Hydraulic Fracture Closure
Authors: de Pater C. J. , Desroches Jean , Groenenboom Jeroen , Weijers Leen 
Published: December 2007

Summary
This paper describes laboratory tests and numerical simulation of hydraulic fracture behavior during propagation and closure. The numerical results predicted the laboratory results during fracture propagation and closure. From the experiments and simulations, the paper provides recommendations for ensuring correct interpretation of field data.
Use of Resistivity Logs To Calculate Water Saturation at Prudhoe Bay
Authors: McCoy D. D. , Grieves W. A. 
Published: December 2007

Summary
At the time of this work, induction- and porosity-log measurements were available in more than 180,000 ft of hydrocarbon column from 428 wells. Water saturations were determined from this areally and vertically extensive database after calibration to oil-base-core (OBC) -derived water saturations. This paper presents the method used to calibrate the log data to the OBC water saturations and reviews the methods used to derive resistivity and formation factor values. It also presents field measurements of as-received core-plug resistivity and water-saturation values from two oil-base-mud (OBM) -cored wells. Comparisons are presented with both field water saturations and "routine" electrical-property measurements on extracted plugs.
Chemical Tracer Studies To Determine Water Saturation at Prudhoe Bay
Authors: Deans H. A. , Mut A. D. 
Published: December 2007

Summary
The single-well chemical tracer (SWCT) method was used to measure resident water saturation in two wells in the Ivishak reservoir of the Prudhoe Bay field. The tests, performed in 1981, were in API Wells 406 and 488, both of which had been oil-base cored through the Ivishak. The results of the tracer test in Well API 406 were interpreted by conventional SWCT simulation procedures. A three-layer simulator model was used to match the tracer production profiles measured during the test. The average water saturation obtained from the simulator match was 16 ±3% PV, in good agreement with the Dean-Stark analysis of the oil-base cores. The tracer-test results from Well API 488 were more difficult to interpret because of the very low water saturation at this location in the Ivishak. The SWCT method requires a hydrolysis reaction to take place in the formation to produce a product tracer. In this case, the amount of water present was so small that very little product tracer was formed. The interpreted Sw for this well was 2 ±2% PV, again in reasonable agreement with the oil-base-core measured value of 3.8%.
Mechanisms Controlling Filtration at the Core Bit for Oil-Based Muds
Authors: Warner H. R. , Rathmell J. J. 
Published: December 2007

Summary
Laboratory half-scale coring experiments using 4-in.-diameter reservoir rock samples were conducted with field oil-based muds (OBM). The OBM were formulated to have low water content and low fluid loss to minimize the potential impact of the invading OBM filtrate on connate water saturations (SW). The OBM had been used previously during Prudhoe Bay (Alaska) field coring operations conducted to obtain connate Sw measurements. Laboratory overbalance pressure and temperature were similar to the reservoir downhole environment. The coring test data were OBM filtrate volume generated during coring, pressure in the rock beneath the bit as the bit approached, and pressure in the half-scale 2-in. core during and after the core bit passed by. Also, at the end of each test, dynamic and static OBM filtrate volumes were measured while only circulating the mud and with no mud flowing. OBM filtrate properties, viscosity, emulsifier content, water content, and interfacial tension (IFT) were measured after coring was concluded. Sw was measured before and after coring.
Conclusions from these tests are as follows.
The pressure measurements show that the OBM filter cake controls the pressure gradient both in the core and in the rock directly beneath the bit. The pressure gradient across the OBM filter cake took up almost all the pressure difference between the mud and formation pressures, even at the face of the core bit. The OBM filtrate contains approximately 10% of the carboxylate soap and water found in the whole OBM. OBM filtrate IFT is about half the reservoir oil/brine IFT. The invading OBM filtrate properties are similar to reservoir crude. The water-concentration increase in the OBM was approximately the amount expected as a result of freeing water from the rock drilled up during coring. Because of Sw variations within the rock samples, core sample Sw measurements could not be used to quantify any potential water movement in the core caused by OBM filtrate invasion.
These results mean that the pressure gradients in the core during coring are very low, so displacement of water by capillary number effects will not occur, and above the oil/water transition zone, cores taken with OBM similar to the ones used here should yield reliable in-situ Sw values.
Improved Reservoir Characterization in Low-Permeability Reservoirs With Geostatistical Models
Authors: Meehan D. N. , Verma S. K. 
Published: December 2007

Summary
This paper is a field application of modern geostatistical reservoir characterization to a complex, low-permeability gas reservoir. Multiwell history matching with this approach is shown to be significantly better than those done with historical approaches. Important opportunities for additional drilling were identified; however, these additional infill locations required significantly lower well costs to be commercial.
Experiments on Bypassing During Gasfloods in Heterogeneous Porous Media
Authors: Burger J. E. , Springate G. S. , Mohanty K. K. 
Published: December 2007

SummaryMass transfer from a bypassed region to a flowing region is a very strong function of the solvent phase behavior. Diffusion, dispersion, and capillarity-driven crossflow can contribute to this mass transfer in addition to pressure- and buoyancy-driven crossflow. Our experiments indicated that the mass transfer rate increased with enrichment. Liquid phase diffusion played a significant role and capillary pumping did not contribute to mass transfer in the cases studied.
Fracture-Network 3D Characterization in a Deformed Chalk Reservoir Analogue-the Lägerdorf Case
Authors: Koestler A. G. , Reksten Kari 
Published: December 2007

Summary
Quantitative descriptions of 3D fracture networks in terms of fracture characteristics and connectivity are necessary for reservoir evaluation, management, and EOR programs of fractured reservoirs. Our research has focused on an analogue to North Sea fractured chalk reservoirs that is excellently exposed near Lägerdorf, northwest Germary. An underlying salt diapir uplifted and deformed Upper Cretaceous chalk; the cement industry now exploits it. The fracture network in the production wall of the quarry was characterized and mapped at different scales, and 12 profiles of a 230-m wide and 35-m high production wall were investigated as the wall receded 25 m. In addition, three wells were drilled into the chalk volume. The wells were cored and the wellbores were imaged with both the resistivity formation micro scanner (FMS) and the sonic circumferential borehole image logger (CBIL). The large amount of fracture data was analyzed with respect to parameters, such as fracture density distribution, orientation, and length distribution, and in terms of the representativity and predictability of data sets collected from restricted rock volumes.
Reservoir Geochemistry: A Link Between Reservoir Geology and Engineering?
Authors: Larter S. R. , Aplin A. C. , Corbett P. W. M. , Ementon Neil , Chen Mei , Taylor P. N. 
Published: December 2007

Summary
Geochemistry provides a natural, but poorly exploited, link between reservoir geology and engineering. We summarize some current ap-plicationsof geochemistry to reservoir description and stress that, because of their strong interactions with mineral surfaces and water, nitrogen and oxygen compounds in petroleum may exert an important influence on the pressure/volume/temperature (PVT) properties of petroleum, viscosity and wettability. The distribution of these compounds in reservoirs is heterogenous on a submeter scale and is partly controlled by variations in reservoir quality. The implied variations in petroleum properties and wettability may account for some of the errors in reservoir simulations.
Application of Chlorine Dioxide as an Oilfield-Facilities-Treatment Fluid
Authors: Romaine Jennifer , Strawser T. J. , Knippers M. L. 
Published: December 2007

Summary
Both mechanical and chemical treatments are used to clean water-flood-injection distribution systems whose efficiency has been reduced as a result of plugging material, such as iron sulfide (FeS) containing sludge. Most mechanical treatments rely on uniform-line diameter to be effective, while chemical treatments require good contact with the plugging material for efficient removal. This paper describes the design and operation of a new innovative application using chlorine dioxide (ClO2) for the removal of FeS sludge from waterflood-injection distribution systems. The use of ClO2 for continuous treatment of injection brines will also be discussed.
Exxon USA's Hartzog Draw facility in Gillette, WY, was the site for the application described. A total of 4,500 bbl of ClO2 was pumped in three phases to clean 66 miles of the waterflood-distribution system. Results indicated that ClO2 was effective in cleaning the well guard screens, the injection lines, and the injection wells. The addition of excess ClO2 to the frac tanks used to collect the treatment fluids also reduced waste handling and disposal costs.
Field-Scale CO2-FIood Simulations and Their Impact on the Performance of the Wasson Denver Unit
Authors: Hsu C-F. , Morell J. I. , Falls A. H. 
Published: December 2007

SummaryRecent advances in software and hardware technology have made possible the development of field-scale, fully compositional CO2-flood simulations capable of capturing areal variations in performance on an individual well basis. This paper first describes the general methodology developed, including key elements used to construct such large models, followed by the validation of this approach. Two modeling studies conducted on the Wasson Denver Unit are then presented to highlight several of the significant out-comes realized so far: high-grading the profitability of new CO2 projects, pinpointing best-well candidates to return to production, identifying infill and horizontal drilling locations, and identifying and quantifying injectant losses.
Representation of Wells in Numerical Reservoir Simulation
Authors: Ding Yu , Renard Gérard , Weill Luce 
Published: December 2007

Summary
In reservoir simulation, linear approximations generally are used for well modeling. However, these types of approximations can be inaccurate for fluid-flow calculation in the vicinity of wells, leading to incorrect well-performance predictions. To overcome such problems, a new well representation1 has been proposed that uses a "logarithmic" type of approximation for vertical wells. In this paper, we show how the new well model can be implemented easily in existing simulators through the conventional productivity index (PI). We discuss the relationship between wellbore pressure, wellblock pressure, and flow rate in more detail, especially for the definition of wellblock pressure. We present an extension of the new approach to off-center wells and to flexible grids. Through this extension, the equivalence of various gridding techniques for the well model is emphasized. The key element is the accurate calculation of flow components in the vicinity of wells.
Incorporation of Western Components With Russian Drilling Operations, Case History of Ardalin Fie d Operations, Timan Pechora Basin
Authors: Brady Steve , Reyna Erick 
Published: December 2007

Summary
Polar Lights Co. (PLC) is a 50/50 joint venture (JV) formed by Conoco and Arkhangelskgeologia (AG), a Russian geophysical association, to exploit reserves in the Timan Pechora Basin. Ardalin was the first field to be developed under this JV. Three Uralmash 3-D-86 rigs supplemented with western components, materials, and services were used to successfully accomplish the development drilling. This paper identifies the major Russian and western rig equipment merged on the rig and the Russian and western materials and services used during the drilling operations.
Case Histories and Applications of a New Slimhole MWD Multiple-Depth-of-Investigation Resistivitiy Sensor
Authors: Ball Scott , Yee S. P. , Maranuk Chris , Bittar M. S. 
Published: December 2007

Summary
The use of measurement while drilling (MWD) resistivity tools in boreholes 8½ in. and greater in diameter has evolved over the past 10 years from a little-used, qualitative service to a routinely used quantitative service in directional, horizontal, and extended-reach wells. Today's applications include reconnaissance logging, geo-steering, pore pressure evaluation, wireline replacement, and enhanced formation evaluation.
Over the last several years, there has been an increasing trend worldwide toward drilling smaller boreholes to optimize the costs of tubulars and gain greater drilling efficiencies. Until recently, there have been no MWD resistivity tools available for logging 6-in. diameter boreholes. A new multiple-depth-of-investigation MWD resistivity sensor housed in a nominal 4$34-in. diameter drill collar has been developed for use in slimhole drilling operations.
This new MWD resistivity sensor provides eight different depths of investigation in any mud type and allows for derivation of the flushed zone resistivity, true resistivity, and the diameter of invasion across a wide range of formation resistivities. The tool is designed for boreholes larger than 5⅞ in. in diameter and can be used in medium-radius drilling applications.
Extensive operations in the North Sea, Gulf of Mexico, south Texas, Middle East, Alaska, and Australia have demonstrated a variety of applications. Slimhole MWD resistivity has been shown to have use in geosteering horizontal wells to maintain and optimize wellbore placement. Additionally, it allows determination of true formation resistivity and diameter of invasion for formations with invasion effects and provides for application of advanced modeling techniques to enhance formation evaluation and log interpretation.
Survey of Electrical Submersible Systems Design, Application, and Testing
Authors: Durham M. O. , Lea J. F. 
Published: December 2007

Summary
The electrical submersible pump industry has numerous recommended practices and procedures addressing various facets of the operation. Ascertaining the appropriate technique is tedious. Seldom are all the documents available at one location. This synopsis of all the industry practices provides a ready reference for testing, design, and application of electrical submersible pumping systems. An extensive bibliography identifies significant documents for further reference.