bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stochastic Boolean Simulation of Fluvial Deposits : A New Approach Combining Accuracy with Efficiency.
Authors: Viseur Sophie 
Published: December 2007

Summary
Object-based approaches seem particularly suitable for sim-ulating large-scale heterogeneities, as they directly incorporate information such as dimensions, sinuosity and amplitude. How-ever, these approaches are often based on a simulated annealing process, that may converge slowly when numerous constraints should be honored. For this reason, we propose in this paper a direct approach, enabling well markers to be honored by a set of simulated large-scale heterogeneities, such as the channel- belt bodies, within an overbank deposit underground. Our approach enables to combine results from the realm of CAD with stochastic procedures and sedimentological results. Therefore, we propose here a method driven by the simulation of avulsion events, which results in a geologically coherent fluvial archti- tecture. Another interesting aspect of our method is that it is very easy to extend by adding the capability to account for deterministic data.
Tracking Miscible Processes in the Subsurface Utilizing Time Lapse Shear Wave Seismic Data
Authors: Bard Karen C. , Pranter Matthew J. 
Published: December 2007

Abstract
The Reservoir Characterization Project (RCP) is an industry- sponsored consortium. Its mission is to develop and apply 3-D and 4-D (time-lapse), multi-component seismology and associated technologies to improve reservoir performance and hydrocarbon recovery while reducing environmental impact. Current research is focused on utilizing 4-D multi-component seismic to track a CO2 injection project at the Central Vacuum Unit, Lea County, New Mexico. This field produces from the San Andres reservoir, a shallow shelf carbonate reservoir located on the Northwestern Shelf of the Permian Basin, Southeastern New Mexico (See Figure 1). Figure 2 is a detailed schematic of the seismic and geologic/reservoir simulation areas. Also included within this diagram is the type, quantity, and location of the available data. This portion of the Central Vacuum Unit is in the area where the Lovington siltstone is present. The Lovington effectively separates the San Andres into two producing intervals.
A CO2 Huff-n-Puff pilot project was performed in well CVU-97 at the Central Vacuum Field and the repeated 3-D, 3-C seismic surveys were performed from October 1995 to December 1995. The initial survey was acquired prior to CO2 injection. The second survey was acquired during the "soak" period of the Huff-n-Puff process after fifty (50) million SCF of CO2 had been injected into the well during a four (4) week period.
Interpretation of this time lapse seismic data showed an anomalie due south of the CVU-97 well in the vicinity of the observation well, CVU-200. The simulation results showed an increase in CO2 concentration going in the same direction. Caution needs to be applied in the emphasis placed on these results due to the relatively small volume of CO2 injected during the pilot program. However, the results demonstrate the potential of using shear seismic data in tracking miscible processes. It is also interesting that the simulation results indicate that the shear waves seem to be more sensitive to the change in fluid properties rather than pressure.
The staged implementation of the CO2 injection program started in the spring of 1997. Injection started in the 4-D seismic area in April 1998. In November of 1997 a new base line of multicomponent seimsmic data was acquired. The time-lapse seismic acquisition was performed in November of 1998. Interpretation of these results is still ongoing.
Analysis of Overpressured Reservoirs with a New Material Balance Method
Authors: Wang S. W. , Stevenson V. M. , Ohaeri C. U. , Wotring D. H. 
Published: December 2007

Abstract
This work presents application of a new material balance method to detect aquifer influence and calculate water influx and original gas in place for four over-pressured reservoirs. Calculation of water influx needs to satisfy a set of three equations as opposed to the existing method of one equation of unit slope. In each application, the presence of aquifer influence was identified first, and then material balance was used to determine original gas in place and water influx. The overpressure effect was handled by integrating rock compressibility over operating reservoir pressure. Compositional effects were modeled with Rv (volatile oil/gas ratio) by matching PVT data using Walsh-Towler algorithm or an Equation-of-State. This new method is internally consistent, which avoids potential pitfalls of existing methods. Comparison with other methods in analyzing overpressure reservoirs shows this new method is more robust and comprehensive.
Chemical Defoamer Reduction with New Internals in the Mars TLP Separators
Authors: Chin R. W. , Inlow H. L. , Keja T. , Hebert P. B. , Bennett J. R. , Yin T. C. 
Published: December 2007

Abstract
High injection rates of chemical defoamers had been required to operate the production and test separators on the Mars TLP. In an effort to reduce the chemical consumption, different means of mechanically breaking the foam were investigated in the test separator: gas outlet axial flow demisting cyclones and inlet cyclones. For two different wells, the chemical rate was reduced by 20% and 80% respectively when the existing vane packs were replaced by axial flow demisting cyclones using liquid carryover in the gas outlet as a performance measure. Additionally, the chemical rate was further decreased for several wells by about 30% by replacing the existing 6-tube cyclone inlet with a different design single tube cyclone inlet. On the basis of the successful test separator results, the four main production separators were retrofitted with new internals. Chemical reduction has been on the order of 50%. Description of the old and new internals, test separator results, and the main vessel retrofits are discussed in this paper.
A Comparison of Wireline and Drillstem Test Fluid Samples From a Deepwater Gas-Condensate Exploration Well
Authors: Witt C. J. , Crombie A. , Vaziri S. 
Published: December 2007

Abstract
Successful sampling of gas-condensates is not straightforward with wireline fluid sampling tools, and ambiguous results are often obtained. As a result well testing has often been regarded as the only method of ensuring representative samples. However, testing is expensive and environmentally unfriendly so to be able to rely on wireline fluid samples would be of great value in exploration and appraisal. Few examples exist where both test and wireline samples have been obtained and compared.
In a recent deepwater exploration well offshore Mid-Norway (6305/7-1 Barden) which confirmed the presence of hydrocarbons in the southern extension of the Ormen Lange Dome structure, BP took both wireline and DST samples. This study compares the two sample types and discusses the sampling operations.
The drillstem test was justified by the requirement for high quality PVT samples which were needed to give an accurate assessment of the liquid content of the gas. This is critical to determining the processing requirements in a future development of the discovery. The well was drilled in 860m of water and the cold wellbore conditions were considered a key risk to wireline fluid sample quality. The well was drilled with water-based mud and a relatively dry gas (5–30 bbls/mmscf) was expected; the dew point was unknown. The MDT tool was used to take wireline samples using a ‘low shock’ sampling technique (controlled drawdown). The test samples were taken isokinetically from the separator and just upstream of the choke.
The two sets of samples show a remarkable similarity in fluid properties, encouraging us to believe we may be able to rely on wireline samples in future wells. The reasons for the success are discussed.
This experience demonstrates that, where water based-mud is used, representative fluid samples can be obtained from undersaturated gas-condensate wells using the MDT wireline fluid sampling tool, even in a cold deepwater environment. This experience could enable operators in future to minimise or avoid the need for well testing.
Deliverability Enhancement via Advanced Fracturing Technology in Gas Storage Wells
Authors: Reeves S. R. , Pekot L. J. , Koperna G. J. , Ammer James R. 
Published: December 2007

Abstract
As a result of formation damage, individual US gas storage wells are prone to deliverability loss at a reported average rate of 5% per annum. To bypass this damage and sustain/enhance well deliverability, several new and novel fracture-stimulation technologies have been tested in gas storage fields across the U.S. as part of a joint U.S. Department of Energy and Gas Research Institute R&D program that began in 1994. These new technologies include tip-screenout fracturing, hydraulic fracturing with liquid CO2 and proppant, extreme overbalance fracturing, and high-energy gas fracturing. This paper presents, in summary form, the final results obtained from this multi-year R&D project, which concludes in 1999.
A total of nine field test sites have been involved in the project; fracturing operations at all sites is completed, and limited post-stimulation deliverability and pressure-transient testing remains for each. In total, over 30 new and novel fracture treatments have been performed, close to 100 deliverability and pressure transient tests performed, and about 45 pre and post-fracture diagnostic tests performed.
Significant accomplishments have been numerous. First, the potential application of the various new and novel fracture stimulation technologies to gas storage wells has been demonstrated. Secondly, a lack of analytical design tools has been identified for some of the fracture stimulation technologies investigated. In response, a dynamic fracture and wellbore simulator has been modified to model the extreme overbalance fracturing process, and for the first time EOB downhole pressure records have been collected for analysis. Similarly, for the first time, downhole pressure/temperature records have been collected for a liquid CO2 with proppant fracture treatment. Finally, a comprehensive data set of multipoint deliverability and pressure transient tests has been assembled. This has provided a unique insight into the impact of fracture stimulation on gas storage wells, particularly with respect to the reduction of important non-Darcy flow effects, deliverability profiles, post-frac cleanup effects and how these factors change over time.
Based on the results derived from the project, conclusions have been drawn concerning the applicability and utility of these technologies, storage well damage conditions and remediation candidate selection, and future technology needs.
4D Seismic Modelling of the Statfjord Field: Initial Results
Authors: Al-Najjar N. F. , Brevik I. , Psaila D. E. , Doyen P. M. 
Published: December 2007

Abstract
As part of a major drive to improve recovery in the Statfjord Field, a large-scale 4-D seismic monitoring program was recently undertaken by the operator. One of the objectives of the 4-D program is to identify unswept oil pockets and zones experiencing early water influx in the producing sandstones of the Middle Jurassic Brent Group. A base 3-D seismic survey, acquired in 1979 at the beginning of production, plus two repeat surveys acquired in 1992 and 1997 have been processed and cross-equalized for 4-D analysis. To assist the interpretation of reservoir fluid movements from the time-lapse seismic data, a detailed 3-D earth model has been constructed by integrating log data from 180 wells with flow simulation results. The model framework consists of a series of 3-D stratigraphic grids spanning the Upper and Lower Brent reservoirs plus the encasing formations. Grid-cell reservoir properties include static parameters such as porosity and volume of clay as well as pore pressure and water saturation predictions downscaled from the flow simulation grids for each seismic survey time. Time-dependent elastic parameters such as P-wave and S-wave velocity, density and acoustic impedance have been computed at the three survey times and stored as extra grid-cell attributes. This computation uses a rock physics model linking the elastic properties in each cell to porosity, volume of clay, and saturation and pressure values extracted from the flow simulator. Synthetic amplitude volumes have been generated via forward modelling of the 3-D elastic models for the three survey times. Difference volumes derived from the synthetic datasets are thus representative of the seismic signature of the fluid movements predicted by the flow simulator.
Using 3D seismic-derived information in lithofacies simulations. A case study
Authors: Beucher H. , Fournier F. , Doligez B. , Rozanski J. 
Published: December 2007

Abstract
This paper details a methodology for taking into account seismic information into 3D high resolution stochastic simulations of lithofacies. The simulation is based on a non stationary truncated gaussian approach. Within this frame, a 3D matrix of facies proportion is built. It is estimated from both well and seismic-derived proportions. Thus the seismic attributes are previously turned into soft estimates of proportions with different possible statistical calibration techniques. An application of this methodology to the simulation of lithotypes for a carbonate reservoir is described.
Borehole Stability of Multilateral Junctions
Authors: Aadnøy Bernt S. , Edland Cecilie 
Published: December 2007

Abstract
The number of multi-lateral wells are increasing in the North Sea area. Potential for improved accessibility and recovery has led to a significant interest both from oil companies and the service industry. With improved technology, these multi-lateral branches will be key elements in the development of the so called "smart" wells.
Several multi-lateral wells recently drilled in the North Sea have experienced problems. One well had severe problems as the casing inside the branch deformed into the main wellbore, making both branches unavailable for reentry. Clearly, the formation at the junction had collapsed, forcing the casing to deform.
A rock mechanics study was undertaken. The hole geometry above the junction was a circular hole, which became oval at the junction, and then split into two adjacent boreholes below the junction. Since the solution to this problem was not found in the literature, a new mathematical model had to be developed to model these geometries. This model was coupled to a stress model and a failure model for the rock. The paper will present the complete models. It was found that both the critical fracturing pressure and the collapse pressure changed as the hole geometry changed from a circular hole.
The paper present a field case using the new models. The study showed that the stress concentration increased as the hole became oval at the junction. It was found that the oval geometry created more severe conditions both for mechanical hole collapse and fracturing. It was also found that at certain borehole pressures, this geometric effect diminished.
One main conclusion of the study is that the allowable mud weight window is smaller at the junction itself compared to the holes above and below. The fracturing pressure is lower, and, the critical collapse pressure is higher in the junction than outside the junction. Therefore, the optimal mud weight is the most important condition for trouble-free drilling of a junction. The optimal stress conditions for the geometries will be defined in the paper, and based on these, the paper will present optimal mud weight selection criteria to drill multi-lateral junctions.
Petrophysical Implications of Laboratory NMR and Petrographical Investigation on a Shaly Sand Core
Authors: Chitale D. V. (Vivek) , Day Peter I. , Coates George R. 
Published: December 2007

Abstract
Nuclear magnetic resonance (NMR) measurements on rocks directly respond to the hydrogen content of the fluids in the pore space. Thus, besides the routine application of NMR in measuring the producible water- and hydrocarbon-filled porosity in the rocks, NMR technology has the potential to characterize the surficial clay-bound water. The exact nature of NMR transverse-relaxation T2 spectra obtainable from the clay-bound water has been discussed in recent studies conducted on both pure clays and reservoir rocks. The paper presents the results of a laboratory investigation on systematically sampled shaly sand rocks. We explore the relationship between the T2 distribution as a function of the rock texture, pore size distribution, clay mineralogy, and clay morphology.
A 10-ft conventional core, cut in water-bearing, clay-rich sandstone, was sampled for this study. Mineralogy, texture, pore size distributions, and clay morphology were analyzed by X-ray diffraction (XRD), thin section petrography, scanning-electron microscopy (SEM), and petrographic image analysis (PIA). In addition, fully polarized NMR signals were acquired from brine-saturated and desaturated samples with inter-echo spacings (Te) of 0.3 and 0.6 millisecond.
NMR porosity, computed by summing the signal in the T2 spectra, match favorably with the helium porosity, indicating that the full spectrum of pore sizes is included in the NMR porosity. The NMR T2 spectra obtained from brine-saturated samples show three distinct T2 classes: 1 to 3, 5 to 20, and 30 to 200 milliseconds. These appear from core properties to be controlled by pore-size changes, which are primarily influenced by the changes in clay type and morphology. The &lt;5-millisecond components likely correspond with &lt;5-μm sized pores typically trapped within the flakes of detrital illite. Features in the 5- to 20-millisecond range are also likely associated with the authigenic aggregates of kaolinite and chlorite that enclose 5- to 30-μm sized pores. T2 spectra obtained from desaturated rocks support the match of the specific features in the T2 spectra to the clays present in the rocks. Finally, the water in the relatively larger pores (30 to 150 μm) is associated with the signals at about 30 milliseconds and greater.
Enhancing Mineral Scale Dissolution in the Near-Wellbore Region
Authors: Williams G. D. , Collins I. R. , Wade S. R. 
Published: December 2007

Abstract
Mineral scaling in the near-wellbore region of oil wells can cause significant formation damage and have a major impact on well productivity. Removal of scale from the reservoir is usually limited to chemical means, or, if the completion is a cased hole, to re-perforating through the damage. Chemical removal of scale from the reservoir is limited by the contact that can be achieved between the scale deposits and the scale dissolver chemical, and by the volume of chemical which can be injected. In addition, scale deposits can become coated in hydrocarbons, preventing contact between the deposit and the chemical dissolver. Furthermore, owing to the nature of the dissolvers (comprised of chelants and acids), there is the potential for the dissolver to cause formation damage by (i) dissolving cementing minerals thereby generating fines; (ii) swelling authigenic clays; and (iii) forming water blocks. We have developed a proprietary mixture of non-ionic materials which has been shown to enhance the dissolution of both calcium carbonate and barium sulfate scales in porous media (using commercial scale dissolvers in the tests). This chemical, when used as a pre-flush, removes hydrocarbon deposits on the scale surface thus increasing the surface area accessible to the dissolver. In addition, the pre-flush chemical might remediate some aspects of dissolver induced formation damage. In this paper we describe laboratory experiments validating the chemical package.
On-Site, Near-Real-Time Monitoring of Scale Deposition
Authors: Emmons D. H. , Graham G. C. , Holt S. P. , Jordan M. M. , Locardel L. P. , Locardel B. 
Published: December 2007

Abstract
Inorganic scale deposition is a problem associated with petroleum production. Scale deposition is often managed or mitigated by the use of scale inhibitors. The current industry standard for managing scale programs relies on the determination of scale inhibitor concentration in the scaling brine and then relates this concentration to program performance. Scale inhibitor residual tests are not ideal because the tests themselves are often time consuming to run, subject to interference from components in the produced water, and specific to the inhibitor used. There are delays associated if samples are sent off for analysis. Most important, the results offer no direct information about actual scaling potential. This paper presents a novel technique for scale management which involves direct, near-real-time monitoring of the stability of produced water towards scale deposition. Our method couples together a unique piezoelectric sensor for on-site, near-real-time detection of scale deposition with a method of applying low-level stress (addition of scaling cations or anions) to produced water in order to detect incipient scale. The tests can be run on-site, are independent of scale inhibitor, and results are obtained within hours. Lab studies and field studies are presented for barium sulfate scale deposition. The potential for real time on-line monitoring is discussed.
Reconstructing Petrophysical Borehole Images: Their Potential for Evaluating Permeability Distribution in Heterogeneous Formations
Authors: Anxionnaz H. A. , Delhomme J. P. , De Haan S. 
Published: December 2007

Abstract
Borehole electrical images have very high vertical and azimuthal resolution, and thus have proved to be of paramount importance over the past 10 years in assessing formation layering and internal organization. Standard openhole log measurements (e.g., density or photoelectric factor) have also experienced improvements in accuracy and vertical resolution. These improvements are the result of more compact integrated tools and the systematic use of accelerometer-based speed corrections and inclinometry devices to measure the orientation of sensors within the borehole. Recent advances in nuclear magnetic resonance (NMR) logging have also cast a new light on petrophysical evaluation, especially on continuous permeability logs.
The technique proposed in this paper combines information from borehole images and advanced petrophysical logs in a two-step approach. In the first step, a transform or relation is established between two oriented borehole measurements. For example, the transform is computed between azimuthal resistivity from an imaging tool and a high-resolution density measurement, conditioned on the readings of nondirectional volumetric measurements such as neutron porosity, gamma ray and image-derived textural indicators. This transform, which is in most cases inherently nonlinear, is not explicitly determined. Rather, it is approximated by an artificial neural network, which is trained over key representative facies zones. As a quality control step, the procedure uses the resistivity and other measurements to compute a synthetic density curve. This is compared to the actual density log, and error bars are attached to the reconstruction process.
In the second step, the same transform is then applied to each available azimuthal resistivity channel (column in the electrical image) to reconstruct a quantitative density image on the borehole wall from these reconstructed density channels. The same approach provides a method to interpret a permeability curve from NMR data. The recorded orientation of the CMR* Combinable Magnetic Resonance tool skid enables a transform to be established between NMR-derived permeability and azimuthal resistivity, azimuthal density and nondirectional volumetric measurements (neutron porosity, gamma ray and textural indicators). Reconstructed permeability images can then be obtained by applying the transform to the full suite of image channel data.
The proposed technique is illustrated with examples from clastic and carbonate formations. It provides a powerful means to better understand permeability variations in heterogeneous formations.