bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reservoir Geophysics: Seismic Pattern Recognition Applied to Ultra-Deepwater Oilfield in Campos Basin, Offshore Brazil
Authors: Johann Paulo , de Castro Dayse D. , Barroso Alberto S. 
Published: December 2007

Abstract
Usually, seismic data is used in a qualitative approach to detect changes in the waveform and to pick acoustic continuity of a peak and/or a through as a structural mapping tool. The seismic interpretation is a qualitative process for building a geological model. Today, many works try to use the seismic information in a quantitative approach. Seismic interpretation in a quantitative approach is a key process in the integration of geoscience data at scales from basin-wide studies, reservoir focused and field-development process. Quantitative modeling could be deterministic and/or probabilistic. We use, in many steps of a seismic processing sequence, examples of quantitative deterministic modeling like seismic migration, some seismic inversion methodology, etc. Probabilistic modeling can be gathered in two groups: multivariate statistics and geostatistics approaches. Close to probabilistic modeling, we have also the neural network method. In this paper, we focus on the application of neural network modeling for seismic pattern recognition (seismic facies analysis) applied an ultra-deepwater turbidite oilfield reservoir in Campos Basin, offshore Brazil.
Lateral Delineation of Sandstone Bodies Guided by Seismic and Petrophysical Data Using Geocellular Model: Cañadon Seco Formation, San Jorge Basin, Argentina
Authors: Guerberoff David , Zucchi Hector , Marcos Victoria , Robles Gervasio 
Published: December 2007

Abstract
The studied area is characterized by sandstone-shale complexes vertically arranged in a column of approximately 200 m. Conventional well correlations provide high uncertainty in sandstone prediction because of the high variability and small lateral extension of the bodies. We rely on geo-statistical techniques of interpolation of the petrophysical variables supported by seismic derived attributes. Seismic-petrophysical matrixes and cross plots were constructed to high correlation coefficients. Having the linear correspondence between the variables, an adjusted function allow us to find the unknown values (petrophysical) from the seismic data using geo-statistical methods such as Krigging and Co-Krigging. The grids of petrophysical values feed a geocellular model where they are volumetrically interpolated. This static model can be used through "up scaling" in a future dynamic model for reservoir simulation.
Horizontal Underbalanced Drilling in Northeast Brazil: A Field Case History
Authors: Cunha J. C. , Rosa Fábio Severo , Santos Hélio 
Published: December 2007

Abstract
This paper describes aspects related to planning and execution of four horizontal wells drilled underbalanced in the Estreito Field. This field is located in Brazil's Northeast Region (fig. 1) and has its production zones depleted. It was discovered in 1982 and today it has more than 700 wells. Estreito field has its producing reservoir very shallow and the formation is very unconsolidated, these poses especial challenge to achieve and maintain underbalanced condition at all times during the drilling operation, requiring especial care not only during the planning, but also for the execution of the well operations. In order to achieve the required bottomhole pressure (ECD=6.9 ppg) nitrogen was injected into the water base drilling fluid, through the standpipe. Since the wells were horizontal, it was required the use of electromagnetic MWD/GR once the regular MWD would not work properly on a gasified fluid. In these wells it was successfully tested a compact vertical gas-liquid separator with an automated control system and data acquisition system developed by Petrobras. A skimmer was used for the solids-drilling fluid-oil separation.
What Have We Been Doing Wrong in Wellbore Stability?
Authors: Santos Helio , Perez Roberto 
Published: December 2007

Abstract
Identification of the correct cause of wellbore instability is the key to quickly solve the problem. This paper presents some results of tests conducted to check the behavior of preserved shale samples when immersed in different solutions, trying to identify the importance and relevance of the osmosis as well as the effect of other components in the mud, such as the emulsifier. Results showed that not only the salinity of the mud is important. Also, in some situations, rock swelling did not follow what states the osmosis theory, leading to a conclusion that other phenomena are relevant and with a similar order of importance.
The paper also discusses the mechanism of micro-cracking with subsequent fluid penetration, and the use of a truly non-invasive fluid to avoid the instability. Field cases are reported, demonstrating the effectiveness of using such approach. The paper also presents the problems ofcurrent rig site monitoring tests that can induce wrong interpretation of the real cause of the problems.
Shell Separation Technology from the Wellhead to the User
Authors: Bergerman S. D. , Polderman H. G. , Bravo J. L. 
Published: December 2007

Abstract
Advantaged separations technology has proven to be key in the success of the hydrocarbon production processes of Shell over the years. R&D as well as benchmarking efforts over the years have yielded a varied slate of separation process technology that has found wide application in the field. The Shell separation technologies cover the range of phase separation, distillation hardware, and process design and are pervasive in the hydrocarbon supply chain from production to manufacturing.
Diadema Project - Underground Gas Storage in a Depleted Field, in Patagonia, Argentina
Authors: Rodríguez Juan José , Santistevan Pedro 
Published: December 2007

Abstract
Underground gas storage is a common activity in countries with major transport and distribution gas pipeline infrastructures, which allows to efficiently resolve demand seasonality problems.
So far, Argentina, with major winter demand peaks and its fields located thousands of kilometers away from consumption centers, has not developed UGS facilities, despite the maturity the industry has reached in the country, which has one of the highest rates of natural gas participation in the power matrix worldwide (47%).
The first ever underground gas storage project in Argentina is being carried out in the Diadema field, located near the city of Comodoro Rivadavia - Province of Chubut, with injection and withdrawal operations starting as of 2001. (Fig. 1)
The goal of this project is to contribute to modulate oil and gas production in the fields of the region, transporting and storing part of the overproduced gas in the Austral and San Jorge Basins during summertime, to have the necessary gas available during the winter peak season, allowing producers to comply with their contract obligations.
With this goal in mind, several studies have been carried out, including reservoir modeling and simulation studies, gas injection and interference tests, the workover of gas input wells and monitoring wells, as well as the construction and revamping of the necessary surface facilities for storage operations.
Considering the size and geographic location, the Diadema project will be a pilot operation in the region, which will serve as a model for future undertakings.
A Field Methodology to Estimate the Zone of Maximum Probability of Asphaltene Precipitation Occurrence
Authors: Avila C. , Russo A. , Flores E. , Hidalgo O. 
Published: December 2007

Abstract
Asphaltenes precipitation is one of the major operational problems affecting oil production in the Northern Monagas fields of Eastern Venezuela. Being a phenomena that depends primarily on crude composition, pressure and temperature, it may occur inside the pore space, downhole along the producing strings, at the well head, inside flow lines, separators and gas treatment plants. In most cases, the cleaning of pipes and production strings is done through chemical treatment. For downhole treatment, coiled tubing or snubbing units have to be used, thus increasing production costs.
A field methodology based in the influence of pressure in asphaltenes precipitation has been designed and implemented to estimate the zone of maximum probability of asphaltenes precipitation. Nodal analysis is applied to determine pressure versus depth behavior at the well for different operational conditions. Gross composition chemical analysis and asphaltenes dispersion curves of the crude oils are required. Knowing the saturation pressure and the flocculation onset pressure, the methodology allows the determination of the most probable range of depths at which asphaltenes precipitation will occur.
The purpose of this methodology is to determine the optimum operational conditions that maximize production at minimum risk of asphaltenes precipitation, as well as to select the better preventive measure for each particular case, thus maintaining overall control of the asphaltenes plugging problem.
In this work, field applications of the methodology are shown. Depending on the depth range of asphaltenes precipitation occurrence, reperforation of the producing interval, hydraulic fracturing or chemical treatment is recommended. Application of the methodology is becoming routine in the Northern Monagas fields. An expert system based on the methodology is under development to extend its application throughout the area.
Integrated Petrophysical Model, C4 and C5 Reservoirs, VLA-6/9/21 Area, Block 1, Lagomar, Lake Maracaibo, Venezuela
Authors: Madariaga M. , Garcia E. , Barbato R. , Quaglia A. , Porras J. C. 
Published: December 2007

Abstract
Reservoirs C4 and C5 belong to the VLA-6/9/21 area of the Lagomar Segregation, and are located in the East Flank of the Block I, Lagunillas field, Lake of Maracaibo Basin, Western Venezuela. The C sands correspond to the Misoa formation of Eocene age. For the present study, 25 wells of the area were selected, 12 of which belong to a special Integral Field Laboratory, and have enough information that allowed the generation of a model that can be extrapolated to other wells in the field. Using all this information, certainty maps for each reservoir were constructed. Pore throat radius was estimated from porosity and permeability data from conventional core analysis, along with capillary pressure data. Winland's equation, an empirical relationship between porosity, air permeability and pore throat radius corresponding to a mercury saturation of 35%, was used for reservoir C5. In 1992, Winland's work was modified by Pittman, and for reservoir C4, the R45 Pittman equation was applied. Cementation and saturation exponents (m, n) for C4 and C5, were determined from core analyses. The resistivity of the formation water (Rw) was estimated from chemical analyses and by the SP curve method. Clay volume (Vsh) was obtained using Larionov's tertiary rocks model, which correlated well with X-Ray difraction analyses. Once the key wells were evaluated using the Waxman-Smits water saturation model, which resulted in a good match between core and log data, the evaluation was extrapolated to the other new and old wells of the area. Five different rock types were identified: Mega, Macro, Meso, Micro, Nanno, and were used to construct cross-sections showing their lateral distribution. Flow units were identified using the Modified Lorenz Plot and the Vertical Flow and Storage Diagram. Rock type areal distribution maps were also constructed, and have an excellent agreement with the sedimentary facies maps obtained from the sedimentological study.
Designing a Mobility Control Foam for Western Venezuela Reservoirs: Experimental Studies
Authors: Romero C. , Valero E. M. , Alvarez J. M. , Romero O. M. 
Published: December 2007

Abstract
This paper presents the results of laboratory tests, performed in a mobility control foam design for Western Venezuelan Reservoirs. In this operational area, two Water Alternate Gas (WAG) injection projects are currently under way using natural gas, but they are expected to change to nitrogen.
The tests presented in this paper were performed mainly with nitrogen, although a final displacement test was designed using fluids that are currently under use in the Lagocinco VLE WAG injection project. The final goal was to achieve a mobility control foam, for gas profile modification in WAG injector wells.
The experimental work was divided in several steps: (1) preliminary screening tests for adequate surfactant selection; (2) mobility reduction tests at average Western Venezuelan conditions; (3) adsorption tests; and (4) a final displacement test in a composite reservoir core using fluids and conditions for the Lagocinco VLE Field.
The selected surfactant for the foam was an alpha oleofinsulfonate (AOS) combined with a fluorinated surfactant for added stability to oil. Surfactant-gas co-injection was used in all core displacement tests as injection scheme. The foam achieved a Mobility Reduction Factor (MRF) of 100 at average Western Venezuelan conditions, while at Lagocinco VLE conditions the MRF values were as high as 800.
ASP System Design for an Offshore Application in the La Salina Field, Lake Maracaibo
Authors: Hernández Clara , Chacón Larry J. , Lorenzo Anselmi , Baldonedo Abel , Jie Qi , Dowling Phillip C. , Pitts Malcolm J. 
Published: December 2007

Abstract
The La Salina Field in the eastern coast of Lake Maracaibo, Venezuela, was designated as a Laboratorio Integrado de Campo (Integrated Field Laboratory, IFL) by PDVSA to evaluate the potential application of different EOR processes. One of the main goals at La Salina FIL was to evaluate the alkaline-surfactant-polymer (ASP) technology potential in an oil reservoir near the end of its waterflood life.
La Salina produces a medium gravity crude oil (25 °API) from LL-03/Phase III Miocene reservoir at 915 m (3,000 feet). The feasibility of applying the ASP technology was based on a series of experiments including fluid compatibility, chemical thermal stability, spontaneous emulsification, interfacial tension between crude oil and ASP solution, chemical retention in the porous media, and physical simulation using reservoir core samples. The laboratory design involved twenty-three commercial surfactants, five polymers, and two alkalis. Interfacial tension reductions in excess of 25,000 fold were observed for a variety of ASP solutions. Type II- and Type III spontaneous emulsification, both considered optimum, were observed. Linear coreflood results indicate that high molecular weight (partially hydrolyzed polyacrylamide) polymers can be injected into La Salina sand at about 800 mg/L. Radial sandpack corefloods produced an average oil recovery of 46% OOIP with water injection. Injection of 30% pore volume of ASP solution followed by 30% pore volume of polymer drive solution produced an average additional 24.6% OOIP for an average total oil recovery of 70.2% OOIP.
The design of the injection plant for La Salina is a challenging task since this will be the first offshore application of the ASP technology in the world. Preparation and transport of a phase stable ASP solution, through the injection lines and into the reservoir, that has the designed chemical concentrations and physical characteristics are crucial for a successful project. The initial decision for the plant design was to use an existing platform instead of a barge for construction of facilities. As a result, critical parameters such as: treatment sequence, equipment footprint, and storage space for injected and treatment chemicals were considered.
The Study of Oil/Water Separation in Emulsion by Membrane Technology
Authors: Fernández Laura G. , Soria Carlos O. , García Tourn Carolina A. , Izquierdo María Sánchez 
Published: December 2007

Abstract
Water treatment plants use conventional processes like hydrocyclones and air up-floating equipment to separate oil from water. However, these devices are not effective at removing oil drops with small diameters.
In this work, the use of membranes to treat oil-water emulsions is analyzed. The performance of microfiltration ceramic and ultrafiltration polysulfone membrane in laboratory scale is studied. Drop of less than 50 μm diameters is the subject of our interest.
The new European standards will require less than 10 ppm hydrocarbons. Such standards could easily be met by using membrane technology. The most serious limitation of this technology is a continuous permeation flux decrease due to fouling, which is associated with different membrane-solute interactions, operation conditions, transmembrane pressure, temperature, etc. Emulsions with different concentrations (1000, 500 and 250 ppm) and different droplet sizes are studied. These emulsions are synthesized and characterized in the laboratory.
The results found for different nominal molecular weight cut-off, membrane materials and operation condition permit to analyze whether this alternative technology is suitable to solve a separation problem, which is of great environmental interest.
Resolution of Environmental Passives in the Refinery Lujan of Cuyo of Repsol YPF S.A.
Authors: Fernández L. , Vera F. , Ercoli E. 
Published: December 2007

Abstract
The objective of the following work is to show the different techniques applied for the recovery of passive environmental and the convenience of the application of each one in the different cases. In the Refinery of Lujan of Cuyo of Repsol - YPF S.A. were existing environmental passives of different characteristics. One of them was consisting of pools to sky opened without waterproofing that was containing a volume of flowing material of approximately of 20000 m3 of mud contaminate with heavy and light hydrocarbons, phenol, exhausted caustics, mercury, lead and other metals in high concentrations. The other was consisting of a surface of approximately 50000 square meters of contaminated soils with hydrocarbons originating from funds of tanks and dry muds resulting of the continuous centrifugation of muds. Complying with the commitment assumed his environmental policy of remedying the passive, the Refinery beginning an investigation program to find the more convenient alternatives for each case. At the moment of considering the alternatives of solution they have had into account technical, environmental and economic aspects. After analyzing the various existing technologies was opted for using two types of different treatments as compared to the different realities that was presenting each case. In the first case was opted for the stabilization technique that was developed in the area of the refinery, in base to tests accomplished at plant level pilot. Surpassed this stage were begun the tests to industrial scale what permitted to solve the problem in a period of 6 months. In the second case was opted for the use of bioremediation techniques: landfarming and aerated accumulation. These techniques were developed along with the National University of Cuyo. In either cases it is accomplished a monitoring of the results with the University and the organs of environmental control, being obtained successful results, with the recovery of the discussed soil.
Physical and Numerical Simulation of an Extra-Heavy Crude Oil Downhole Upgrading Process Using Hydrogen Donors Under Cyclic Steam Injection Conditions
Authors: Ovalles Cesar , Martinis Jorge , Pérez-Pérez Alfredo , Cotte Edgar , Castellanos Luis , Rodríguez Héctor 
Published: December 2007

Abstract
Physical simulation experiments of a Downhole Upgrading Process showed that use of a hydrogen donor additive (tetralin) in the presence of methane (natural gas) and the mineral formation under steam injection conditions (280°C and residence times greater than 24 h) led to an increase of at least three degree in API gravity of the treated Extra-Heavy Crude Oil, three-fold viscosity reduction and, approximately, 8% decrease in the asphaltene content with respect to the original crude. In the present work, a continuous bench scale plant was used at different temperatures (280-315°C) and residence times (24-64 h) for carrying out kinetic studies. A reaction model involving four pseudo-components (light, medium, heavy and asphaltene fractions) was used and the kinetic parameters (pre-exponential factors and activation energies) were determined. Using these data, compositional-thermal numerical simulations were carried out and validated using the bench scale data. The results showed a good match between the calculated and experimental °API gravities of the upgraded crude oil (average relative error 4%).
Using the previous model, the Downhole Upgrading Process was numerically simulated under cyclic steam injection conditions (injection of 2500 bbl/d of 1:1 steam/tetralin with 75% quality steam) for 20 days, followed by 10 days of soaking period) in a typical Orinoco Basin reservoir (9°API). The simulation runs showed the production of 12°API upgraded crude oil, accumulated over a 100 day-cycle. However, a reduction in the percentage of conversion of tetralin was observed (0.8%) in comparison with the bench scale experiments (3%), which was attributed to gravitational segregation of the steam coupled with low mixing efficiency of the hydrogen donor with the extra-heavy crude oil at reservoir conditions.
Rigorous Modelling of Fractures in a Porous Medium
Authors: Saghir M. Ziad , Edali Mohamed A. , Islam M. R. 
Published: December 2007

Abstract
While fractured formations are possibly the most important contributors to the oil production worldwide, modelling fractured formations with rigorous treatments has eluded reservoir engineers in the past. To-date, one of the most commonly used fractured reservoir model remains the one that was suggested by Warren and Root more than three decades ago. In this paper, a new model for fractures embedded in a porous medium is proposed. The model considers the Navier Stokes equation in the fracture (channel flow) while using Brinkman equation for the porous medium. Unlike the previous approach, the proposed model does not require the assumption of orthogonality of the fractures (sugar cube assumption) nor does it impose incorrect boundary conditions for the interface between the fracture and the porous medium.
The proposed model is derived through a series of finite element modelling runs for various cases using Navier Stokes equation in the channel while maintaining Brinkman equation in the porous medium. Various cases studied include different fracture orientations, fracture frequencies, fracture width, and the permeability of the porous medium. Finally, a series of numerical runs also provided validity of the proposed model for the cases for which thermal and solutal effects are important. Such a study of double diffusive phenomena in the context of fractured formations has not been reported before.