bluuebunny/crossref_metadata_2025_split huggingface dataset:
Saturation Distribution in a Linear System During Oil Displacement
Authors: Bail P.T. , Marsden S.S. 
Published: December 2007

Abstract
Displacement studies were performed on a Berea sandstone core in which a residual brine saturation was initially present. The oil saturation was determined as a function of time and distance by measuring the electrical resistance of segments of the core. Relative permeability was measured by a modified Penn State method for the same porous medium used in the displacement studies and static capillary pressures were determined for adjacent samples. The shape of the stabilized zone and recovery at water breakthrough were calculated using both measured and computed relative permeability data and these agreed with the experimental. The fraction of brine flowing at a given oil saturation was determined from saturation distribution data at various times and distances during the displacement runs by calculations based on the continuity equation. As the stabilized zone is formed, the shape of the fw vs So curve approaches a straight line for a certain range of saturations.

Introduction
A wide variety of experimental work on fluid displacement in porous media has appeared in the petroleum engineering literature during the last two decades. Along with this has appeared the theoretical treatment which forms the basis of our present concepts in this field. One of the first papers of background interest for this particular study was that of Leverett in which was developed the fractional-flow formula. A short time later Buckley and Leverett presented a form of the continuity equation as well as a method of using it and a simplified version of the fractional-flow formula (gravity and capillary-pressure terms neglected) to calculate the distance which any saturation has traveled in a given time interval. Terwilliger et al observed that after their water gas interfaced advanced a certain distance from the inlet of the system, all gas saturations over a certain interval beginning at the extreme flood front advanced at the same velocity. On the basis of the continuity equation they concluded that the change of fractional flow (gas) with saturation must be constant and this zone wherein all saturations moved at the same rate was named the "stabilized zone." They presented a method of calculating the saturation distribution in the stabilized and non-stabilized zones and obtained reasonable agreement between calculated and experimental values.
Structural Integrity Evaluation of the Heat Exchangers of a Hydrocracking
Authors: Edén Roberto D. , Roman Raúl 
Published: December 2007

Abstract
The objective of this work is to evaluate the structural integrity of the feed-effluent heat exchangers of the Hydrocracking of the Luján de Cuyo Refinery, belonging to Repsol-YPF S.A.
This equipment operates under a hydrogen load at a pressure of 2133 psi and at a temperature that varies between 300°C (572°F) and 400°C (752°F).
An inspection performed during the plant maintenance shutdowns revealed several cracks on the channel of one of the equipment. These cracks had a depth of 2.4 in and a length covering almost all the circumference of the channel. It was concluded after several studies that during the 27 years service period and being exposed to temperatures of above 300°C (572°F), the material suffered an embrittlement process due to a phenomenon known as Temper Embrittlement, and that at room temperature, the material was within the range of brittle fracture.
The commencement of the crack can be associated to the presence of hydrogen, to the effects of local stress concentration and to the plant maintenance shutdowns.
It was estimated that probably the growth of the cracks was produced by the thermal stresses originated during the plant starting and the plant maintenance shutdowns, and that it is facilitated by the embrittlement of the material and by the presence of hydrogen.
A risk evaluation was performed to analyze the feasibility of the continuous operation of the equipment under the described metallurgic conditions.
By accepting a criterion of risk decision, it was concluded that the operation under such conditions was "not desirable" and that situation must be accepted by a high rank executive officer.
A heat exchanger was shut down from service and used to perform several tests to determine its condition and therefore to provide the necessary technical background to the management decision making.
This study was highly significant because the remaining four heat exchangers were in similar metallurgical conditions than the equipment removed from operation and they should continue with their service operation.
Several studies were performed such as Charpy V tests, fracture tests and stress analysis calculations to determine the value of the stress intensity factor (J).
These studies were then used as technical background and support material for decision making in regards to the continuity of the service operation of the equipment for a certain period of time and under certain operational conditions.
Monetizing Gas Reserves: Trinidad and Tobago's Approach
Authors: Marcelle-De Silva J. , Jagai T. 
Published: December 2007

Abstract
The petroleum sector of the Republic of Trinidad and Tobago has made substantial contribution to its economy over the last 90 years. The major contribution during the period 1908 to 1995, came from oil production. Starting in 1996, there were major developments in the gas sector to the extent that revenues from gas production in 2000, exceed that from oil production. This paper reviews the natural gas industry and summarises the factors that contributed to the successful monetization of stranded gas reserves.
The Government of the Republic of Trinidad and Tobago (GORTT) have undertaken many initiatives that have promoted upstream exploration and production activities both onshore and offshore. As a result, a number of investors were encouraged to explore for and develop gas reserves resulting in the proved gas reserves increasing to 22 Tcf in 2000. Policies were also adopted which facilitated the development of a range of petrochemical and other gas based industries. These encouraged investments in the methanol, fertilizer, iron and steel industries. More significantly, Train 1 of a liquefied natural gas plant was commissioned in 1999, and the first shipment was exported in April 1999. This plant is being expanded, with the construction of Trains 2 and 3 presently in progress. Consideration is being given to Trains 4 and 5. The coming onstream of Trains 2 and 3, together with an additional ammonia plant and a methanol plant, will reduce the reserves to production ratio from 37 years at January 2000 to 21 years by December 2003, until more reserves are proved.
Future potential projects aimed at sustaining the development in this sector have also been identified. In this regard, additional deep-water acreage will be placed up for bids, and discussions are ongoing for the establishment of an aluminium smelter plant, additional fertilizer plants, an ethylene project and a gas to liquids project.
A Study on Blowouts in Ultra Deep Waters
Authors: Santos O. L. A. 
Published: December 2007

Abstract
This paper presents the preliminary results of a research project on ultra deepwater blowouts. This research is a part of a comprehensive study currently conducted by Petrobras, the Brazilian oil company, aiming at drilling and producing safely, in terms of well control, in water depths as deep as 10000 feet (approximately 3000 meters). Firstly, the paper presents a mathematical procedure that predicts wellbore pressures and flow properties during a gas blowout using an unsteady state model that considers the multiphase nature of the flow. Coupled to this procedure, there is a gas reservoir model that calculates gas flow rates entering the well during the unloading part of the process and later on during the blowout itself. The mathematical procedure was implemented in a FORTRAN computer program and several simulation runs were performed to analyze the effect of some drilling variables and reservoir properties on blowout flow rates including the effect of the high backpressure generated by the seawater hydrostatic head. Afterwards, the paper shows the modifications implemented in the computer program to make possible simulations of the dynamic kill technique using a relief well drilled by a dynamically positioned vessel. Finally, the results of the simulations are discussed and analyzed and, when pertinent, recommendations for field application are suggested.
Skin Damage Removal Using Coiled-Tubing Vacuum: A Case Study in Venezuela's Orinoco Belt
Authors: Figueroa Jorge , Hibbeler Jeffrey , Duque Luis , Perdomo Lenin 
Published: December 2007

Abstract
The Orinoco Belt in Venezuela contains the largest known deposits of heavy oil in the world. Estimates for proven reserves are estimated to be 1.2 trillion barrels of oil-in-place (STOOIP) and the field covers an area of 5400000 hectares (54000 km2) across three states in Eastern Venezuela. Drilling in the area started in 1953 and over the years new technologies like horizontal drilling have made possible the economic exploitation of previously heavy oil plays. BITOR, a subsidiary of Petróleos de Venezuela S.A. (PDVSA), is an operator in the Cerro Negro field located near Morichal in Monagas State, Venezuela. Recently, Cerro Negro is developed only by horizontal wells, completed with a slotted liner / open hole horizontal. Over time the horizontal section has been increased to improve production, however this has also made it more difficult achieve a clean well. Conventional methods to remove filter cake and drilling fluids were not effective and caused downhole pump problems and formation damage.
Recently a new coiled tubing technique has been devised to clean wells by means of a hydraulic jet pump. The pump creates a pressure drop across the formation sandface and unwanted fluids, polymer residues and solids are transported to surface. This technique is ideally suited to horizontal heavy oil reservoirs where pressures are low and viscosity is high. The technique makes use of Concentric Coiled Tubing (CCT) and a special Vacuum Tool (VT) designed to apply a specific and controllable drawdown. Several jobs were performed on wells in the Cerro Negro with outstanding results. Post job analysis of vacuumed wells has revealed improved bottom hole flowing pressure and increased production compared to non-vacuumed wells. Moreover, analysis of fluid returns shows that significant amounts of polymer residue as well as both drilling and formation solids are being cleaned from the face of the completion.
This paper illustrates the usefulness of CCT vacuum technique and several complementary technologies now being applied. A comprehensive technical review and case study of work performed in the Cerro Negro field are also presented.
Horizontal Water Producers Increase Heavy-oil Recovery Factors
Authors: Boardman D. W. , Zerpa L. B. 
Published: December 2007

Abstract
Morichal-01 is a 9° API heavy oil field located in the Venezuelan Orinoco Heavy-Oil Belt. The reservoir comprises unconsolidated, Darcy permeability channel sands at a depth of 3-5000 ft, and contains a STOIIP of 8.7×109 stb. Development has been on-going since 1956 with a 2% recovery factor to date.
A history matched thermal numerical simulation model showed that recovery is unlikely to exceed 4% of STOIIP using conventional production methods, due to viscous fingering by the aquifer and artificial lift related production problems. Using the simulation model, the authors show that in a relatively undeveloped area of the reservoir close to the aquifer, placing horizontal wells to pump off the aquifer influx substantially reduces viscous fingering and sustained dry oil production can be achieved updip, increasing the recovery factor above 10%. Dry oil production is additionally expected to reduce emulsion problems and costs, improve pump efficiency and reduce disposal costs from uncontaminated produced water.
A Study of the Influence of Number of Components on Compositional Reservoir Simulation Results
Authors: Hildebrand M. A. , Liu K. , Mezzatesta A. G. 
Published: December 2007

AbstractThe number of components used in the compositional simulation of petroleum reservoirs affects both the accuracy and the speed of simulation results. A proprietary, fully automatic fluid characterization technology provides an efficient way to reduce the number of components of reservoir fluid samples used to simulate relevant laboratory tests within a predefined accuracy. This paper focuses on investigating how the number of components impacts the speed and accuracy of real world compositional reservoir simulations.The procedure starts with using PVT laboratory test data to characterize the reservoir fluid behavior under anticipated reservoir production mechanisms. The PVT laboratory test data are matched within a given accuracy by running the proprietary Fully Automatic Reservoir Fluid Characterization package, where the minimum number of components can be set by the user. The characterized EOS parameters are directly exported to a compositional simulator to perform the actual reservoir simulation using different numbers of components and two different simulation schemes, i.e., IMPES and Fully Implicit. Simulations are performed for a range of fluid types, from volatile oils to gas condensates.This paper presents a systematic investigation of how the number of components influences the accuracy of simulation results and the speed of the simulation. Three examples show that this method of reducing the number of components results in a significant increase in the compositional simulation speed while, at the same time, retaining the prediction accuracy.
Supply to a Commercial Network - Planning of Production
Authors: Manitta José Orlando , Di Cugno Carlos , Gaona Miguel Angel 
Published: December 2007

Abstract
The problems related to the supply of oil products to a commercial network are handled. It will be intended to approach these topics in a way that enables to visualize those aspects that have more weight, in order to build a scheme where the resulting costs have been optimized.
The first part of the papers deals with the way of setting up a scenario where the supply will take place, focusing on the planning of production as an alternative to all other remaining possibilities in order to fulfill the supply to a commercial network.
The demand of oil products appears as the basic information required in order to solve the problem, and the details of what this input must involve are given here. All potential alternatives that must compete to fulfill the supply, achieving concomitantly optimization, are also presented in detail.
The way of performing the optimization of logistics and distribution of oil products is detailed as a very important part of the scenario. A general framework that can be adapted to any company that sells products in bulk, independent of its particular features, is used. Work tools are mentioned, among which stands out a software that uses a mathematical model with linear equations and an objective function, that once minimized after running, gives the solutions that achieve economical optimization through minimum cost. This output found is the basis to build the advisable program of logistics and distribution for the period that is being planned.
The setting up of the scenario is completed by application of criteria to appraise oil products and raw materials, providing also some methodologies to keep track of margins of profit in order to envisage from the beginning the most likely behavior of the mathematical model for production programming.
Once the appropriate scenario is completed, the aspects related to programming of production are detailed. Obviously, work tools used are mentioned, and also those elements of major significance taken into account in designing a model for one or more refineries, such as ways of operation, severity of processes, slate of crude oils liable to be processed and their corresponding assays, finished products specifications, possibilities of blending from different streams, uses of additives in finished products, processing in plants of third parties or for third parties, etc.
Estimation of Fluid Properties Using NMR Correlations in Berea Rocks
Authors: Rodrigues Patricia , Romero Pedro 
Published: December 2007

Abstract
Fluid viscosity is one of the most important parameters necessary to establish reservoir production and economic potential. Until the appearance of Nuclear Magnetic Resonance (NMR) techniques in the oil industry, oil viscosity determination was limited to laboratory tests and correlations with API gravity. Nuclear Magnetic Resonance response is the consequence of fluid properties, as viscosity and density, and its interactions with its surroundings. In water wet rocks, oil NMR behavior depends only on its properties, since it has not contact with the pore surface. However, the water attached to the surface has an effect on the global NMR signal. The technique used to overcome this situation is the NMR differential spectrum, which consists in implementing two different polarization times during NMR measurements, one that polarizes all present fluids and the other, which only polarizes the water. This technique has shown good results for sand reservoirs saturated with light oil, since the polarization time of light oil is much greater than the polarization time of water in sandstone. However, this technique cannot be used with confidence, in presence of heavier oil or in rocks where the water has greater polarization time, since both signals can be overlapped. This study is based on the idea of generating correlations to determine fluid properties through the use of mixed NMR signals of oil and water. In the study, we used Berea rocks to determine correlations for API gravity and oil viscosity vs. logarithmic average and 1st quartile of the NMR T2 distribution, for three different echo times (300, 600 and 1200 μs). These correlations were determined in a general form as function of the echo time for free fluids and in saturated samples. API gravity correlations for free fluids and fluids inside the porous media showed similar results, while viscosity results showed the need of a specific correlation for fluids inside the porous media. This work constitutes a preliminary step on the generation of correlations to determine fluid properties inside the porous media.
Productive Innovations for Cementing Liners in Deep Wells
Authors: Valles C. , González O. 
Published: December 2007

Abstract
The objective of this paper is to highlight the results and experiences obtained by the Petroleum Company of Venezuela (PDVSA) as a result of the changes applied to the displacement systems in liners, for the cementing of intermediate and production strings in the deep wells of the North Monagas area, located in Eastern Venezuela.
In the year 1998, there was a 24% drop in the success rate of liner cementing during the well construction process. This resulted in the execution of 11 repair jobs having to be performed to correct primary cement job failures, with an associated cost of US $370,000. Based on an analysis of the execution and evaluation of the said jobs, it was determined that the most recurrent problems were flaws in the displacement system with the different types of hangers used. As a consequence, a more detailed analysis was done which allowed the identification of the most common causes when the failures occurred, such as: the piston effect between the liner displacement plug and the seal bore, and inadequate sealing during the latch-in of the plugs. As a result of the optimization proposals and changes made to the designs in liner hangers used for cementing 7 5/8 inch intermediate and 5 ½ inch production strings, a 22% increase in the success rate was achieved compared to 1998, thus reducing the percentage of repairs to primary cement jobs due to failures in the liner hanger to just one from a total of twenty seven (27) jobs performed in the period 1999–2000. By these changes, a total of US $1,500,000 in additional costs for repairs to primary cement jobs was avoided.
The Use of a Coarse Grid Simulation for History Matching and Development Planning, Quiriquire Deep Field
Authors: Zambrano H. , Rusinek I. , Jalfin G. , Lee Sheng-Tai , Muralidharan V. , Rigatti Vincent 
Published: December 2007

Abstract
The Quiriquire Deep Field located in the Eastern Venezuela is a large and complex compartmentalized accumulation, with a hydrocarbon column of some 3,500 ft. (3000 ft in the gas cap and 500 ft in the oil rim). The appraised part of the field has an estimated 2.0 TCF of Original Gas in Place both free and associated, and 550 MMBO (50 MMBO from the gas cap and 500 MMBO from the oil leg). There is a very significant variation with depth of the stock tank oil API and the standard gas/stock tank oil ratio within the fluid column both in the gas cap and the oil legs (&gt;50 °API to &lt;15 °API). The multidisciplinary study included a static numerical representation of the geological model, taking into account all available information and integrating the vertical communication among formations and the reservoir compartmentalization as inferred from the available performance/dynamic data (mainly pressures, production tests and fluid types). Given the very limited dynamic information available and the limitations of seismic imaging in this area, a History Matched coarse grid simulation model was used as a Material Balance tool to study reservoir compartmentalization; evaluate volumes in place per compartment; and estimate well counts and overall recoveries for alternative development scenarios. A key part of the model was an accurate representation of the complex PVT behavior, including depth profiles of oil content in the gas, oil API gravity and initial Rs; as well as GOC depth estimates for each compartment. The study supports the blowdown of the gas cap as the most commercially attractive and less risky development strategy.