bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Technique for Proppant Flowback and Improved Fracture Conductivities
Authors: Rae Phil , Briggiler Norberto , Di Lullo Gino , d'Huteau Emmanuel 
Published: December 2007

Abstract
Flowback of fracturing proppant during production is a common problem. The consequences of this can be extremely serious. Loss of fracture conductivity can occur due to reduced width, which can be further compounded by partial plugging of the pack by proppant fines. The latter are produced by non-uniform loading on the proppant with resultant failure and crushing. The produced solids can wreak havoc with both downhole and surface equipment, eroding chokes and nipples, plugging flow lines and filling separators. In the case of sub sea wells, the problems are even greater and can compromise well security. Since the 1980's, the standard solution applied for prevention of proppant flow back has been the use of curable resin coated proppant. While this approach has met with some success, it is far from perfect. The use of RCP's can cause fluid compatibility problems and can interfere with well clean up. Such problems have prompted resin manufacturers to modify their products and have also opened the door for the introduction of new technologies. Newer developments have included the use of small fibres to try to bind the proppant pack together or heat-sensitive plastic film to partially encapsulate clusters of proppant. These materials have reportedly been used with some success but concerns have been raised with regard to their effect on fracture conductivity, amongst other things.
This paper describes the current methods in use and presents a new system that actually enhances fracture conductivity and minimises embedment and width-loss, while simultaneously helping prevent proppant back-production.
First Massive Hydraulic Fracturing Treatment in Argentina
Authors: Antoci Juan Carlos , Anaya Luis Antonio 
Published: December 2007

Abstract
In the last two decades, it was usual practice in the oil industry to carry out massive hydraulic fracturing works to stimulate wells with great-heighten layers of interest and/or low permeability sands.
Argentina has had no opportunity so far to make a stimulation work of this type, mainly because of the absence of a layer meeting the principal characteristics needed to carry out a job of this size, considering the lack of equipment required by a service company to face the magnitude of the work in question.
In the year 2000, Pan American ENERGY, a BP Amoco subsidiary, made exploratory works on a sand formation of interest that met the adequate characteristics to try and develop this kind of job.
This paper shows how operator and service company designed this treatment in a team work and how this job was accomplished and came to be the largest stimulation treatment successfully done in Argentina to date. This kind of jobs can open a new way to handle tight gas zones in Argentina.
Crosslinked Methanol: Analysis of a Successful Experience in Fracturing Gas Wells
Authors: Antoci Juan C. , Briggiler Norberto J. , Chadwick Jorge A. 
Published: December 2007

Abstract
Over 200 hydraulic fracturing jobs using crosslinked anhydrous methanol as fracture fluid, have been performed in Argentina since the introduction of the technology in the country in 1992. Initial development of the crosslinked methanol was intended to reduce formation damage caused by swelling clays and capillary blockage related to high fluid surface tension when stimulating gas reservoirs. This paper summarizes the basic development of the technology, presenting recent findings on lower friction pressure, proppant carrying properties, environmental concerns solutions and larger temperature range of application. It also reviews the acquired experience, focused on its application in the field with the most extensive usage in Argentina, and it includes references to the broadening of the span of applications to different gas bearing rocks, higher temperatures and deviated wells; and a brief discussion on safety and cost issues.
A study of the factors influencing the gas flow initiation stress (FIS) at fracture faces after being invaded by fluid filtrate is presented, supported by laboratory tests comparing water base fluid against methanol base fluid.
Finally, the influence of fluid vaporization is presented as a key mechanism unique to methanol that overcomes the effect of FIS (both at the fracture faces and in the propped fracture) in reducing effective fracture length. Methanol vaporization explains that the effective fracture lentgh will approach total propped length resulting in increased early time productivity and ultimate gas recovery.
Stimulation with Hydraulic Fracture of an Upper Cretaceous Fissured Tuff System in the San Jorge Basin, Argentina
Authors: d'Huteau E. , Breda E. , Homovc J. , Petrelli G. , Saavedra B. 
Published: December 2007

Abstract
The siliceous tuff of the Castillo Formation (Upper Cretaceous), shows a high degree of deformation in areas adjacent to faults, generating fissured systems with capacity to drain the hydrocarbons present in the residual rock porosity. Based on the results of the fracture spatial distribution analysis and on the direction of the preferential flow, tests were designed to increase the recuperation of oil from these systems, using hydraulic fractures.
A reprocessing of a diplog with new algorithms, allowed to determine the direction of the natural fractures present in the rock, and to determine the direction of the in situ stresses, and so the expected direction of an induced hydraulic fracture. TCP, directioned with a gyroscope, was used to perforate in the plane of the maximum stress.
In the past, attempts to hydraulically fracture this reservoir gave very poor results, with - in most of the cases - premature screen out due to the existence of multiple fractures. The total pumping of fluids was considered as a fact for the low production due to hydraulic fractures parallel to the fissures plane and/or poor connection between the induced fracture and the wellbore.
In the studied well two different intervals were hydraulically fractured, one successfully, the other not as expected.
Studies on The Effects of Solvents on The Physicochemical Properties of Automotive Gasoline
Authors: Teixeira L. S. G. , Guimarães P. R. B. , Pontes L. A. M. , Almeida S. Q. , Assis J. C. R. , Vianna R. F. 
Published: December 2007

Abstract
In Brazil, some substances are not allowed to be added to commercialised fuel, because their use would imply tax evasion, since these substances are not taxed. Therefore, monitoring the quality of commercialised fuel is a very important issue. This work presents and discusses the influence of the addition of different proportions of n-paraffin, mainly n-hexane, kerosene and diesel oil on the distillation profile and octane number of automotive gasoline. The results show that it is possible to add non-allowed substances while keeping the automotive gasoline within specification limits. This means that much research should be undertaken in order to establish methodologies that can allow inference of the presence of such substances through physicochemical analyses, even at low concentrations.
Government Share and Economic Analysis: Case Study of Campos Basin, Brazil
Authors: Barbosa Décio H. , Gutman José 
Published: December 2007

Abstract
The purpose of this paper is to evaluate the economic potential of oil fields located in deep-water Campos basin, under different cost structure and price scenarios, via-à-vis the government revenue share resulting from the current fiscal terms introduced by the new Petroleum Law. The outcomes show that the Brazilian fiscal regime is competitive in a world basis and the analysed oil fields are economically attractive under the scenarios most likely to happen.
Significance of Project Risking Methods on Portfolio Optimization Models
Authors: Tyler P. A. , McVean J. R. 
Published: December 2007

Abstract
Efficient frontier theory is gaining acceptance as a part of the portfolio analysis process in the petroleum industry. One of the major difficulties companies encounter in creating corporate efficient frontiers is in representing project level risks in a corporate consolidation of value. Full stochastic evaluations require the management of huge quantities of data. As a result several current solutions use multiple discrete outcomes to represent any given project, rather then a complete stochastic distribution. This paper evaluates the differences resulting from using these two approaches to project risking. By examining the optimized portfolio results and the resultant efficient frontier, we are able to draw direct conclusions about the added value attributable to detailed Monte Carlo based evaluations. Since price is the source of most correlation between projects, the investigation was done with and without price as an input variable. It was discovered that the differences between the stochastic and discrete outcome evaluations are not significant when price uncertainty is neglected, but the inclusion of price leads to significant differences if the resulting correlation is not accounted for.
Field Development Decision Making under Uncertainty: A Real Option Valuation Approach
Authors: Dezen F. , Morooka C. 
Published: December 2007

Abstract
Real Option Valuation (ROV) has been developed to assist the decision making process for capital investments, whether R&D programs for new drugs, new petrochemical plants, leases of offshore and onshore acreage, etc (ref 1, 2, 3). The proposed work herein demonstrates that the ROV can be a useful technique and toolbox for the selection of different field development concepts and alternatives. Instead of using discounted cash flow (DCF) techniques only, the paper explains the possibility of adding ROV as part of the decision analysis process and the contributions that this approach will accomplish.
Acoustic and Signal Processing Techniques To Estimate Rock Properties Through Casing: Preliminary Results
Authors: Garcia-Osuna F. , Podio A. L. , Hixson E. L. , Gregory A. R. 
Published: December 2007

Abstract
This paper reports preliminary results of the development of acoustic and signal processing techniques to estimate rock properties through casing. In general, the major factors influencing compressional (P) and shear (S) wave velocities of unconsolidated and consolidated sedimentary rocks are porosity, bulk density, and effective stress. The acoustic impedance of the viscoelastic porous media behind the cemented casing will also depend on these factors, being higher for rocks under water or oil-saturated conditions than for rocks under gas-saturated condition. Stronger local-borehole compressional-wave reflectivity is expected from gas-rock reservoirs than from water or oil-rock reservoirs. In the case of the wet-Berea sandstone, the formation acoustic impedance is similar to the acoustic impedance of the cement layer. Experimental and theoretical studies of ultrasonic wave transmission and reflection for cemented casings and steel-plates with cemented sedimentary rocks were undertaken. Results provide a quantitative means to use acoustic energy to evaluate pore fluid saturant and detect gas, oil, and water interfaces through casing. A time and frequency domain analysis of a selected portion of the reflected signal at normal and oblique incidence is carried out. Laboratory measurements of ultrasonic wave attenuation and penetration into the rock formation through casing are also described and discussed.
Oil Displacement by Water in Vuggy Fractured Porous Media
Authors: Cruz-Hernández J. , Islas-Juárez R. , Pérez-Rosales C. , Rivas-Gómez S. , Pineda-Muñoz A. , González-Guevara J. A. 
Published: December 2007

Abstract
In this paper experimental results obtained for the oil displacement by water within a two-dimensional vuggy fractured porous cell are presented. The experiments were carried out with an acrylic cell, where fractures were represented by channels of 1.6 mm wide, 1.2 mm deep and 19 cm long, whereas the vugs were represented by cylinders of 1 cm diameter and 1.2 mm deep.
The experimental procedure is as follows: the cell, saturated 100% with oil was placed horizontally and at time t=0 water was injected at a constant rate. Photographs were taken to follow the water front in the cell; then, the area corresponding to oil and water was measured. In this way the water saturation in the cell was determined. This water saturation is equal to the oil recovery, considering oil and water as incompressible fluids.
Based on the experimental results, a theoretical model was developed. This model considers that the porous space is constituted by two regions: one that can conduct fluids, called flow region and a stagnant region that interchange matter with the flow region through a diffusion-like process. Analytical solutions for water saturation and normalized oil recovery are presented.
The model fitted in a reasonable way the experimental data of normalized oil recovery, indicating that the theoretical model can be a useful tool to explain oil recovery processes in vuggy fractured reservoirs.
Stochastic Modeling of Rock Heterogeneities Applying New Autocorrelation Estimators and Simulated Annealing
Authors: Saccomano A. F. , Savioli G. B. , Bidner M. S. 
Published: December 2007

Abstract
Two new integral estimators of spatial autocorrelation are put forward and studied. The first is LV (Local Variance), based on the variance of the distribution. It is also an estimator of the average value of the semivariogram within a region. The second, SLV (Semivariogram from the Local Variance), is related to the derivatives of the former. It is an estimator of the semivariogram itself. The behavior of these two estimators is compared to that of the classical semivariogram estimator (CSV) using different data sets. SLV behavior is similar to that of CSV. Both are noisy and present fluctuations that increase with lag distance. Instead, LV is smoother and more resistant to outliers, making it easier to be represented by a theoretical model. Also, LV is less affected by individual values of samples, honoring the general statistics of data.
Afterwards, the ability of the three estimators to model actual spatial variability is tested using the Simulated Annealing optimization technique. This technique has a good performance when any of the three estimators is included in the objective function. It is able to reproduce actual porosity or permeability fields, even when there is a specific spatial structure (such as cyclic, staircase-like, etc). However, LV has a main advantage: it still preserves the main features of the spatial structure even though it is very smooth.
Two Procedures for Stochastic Simulation of Vuggy Formations
Authors: Casar-González Ricardo , Suro-Pérez Vinicio 
Published: December 2007

Abstract
Simulated annealing and stochastic simulation based on indicator kriging are used to describe vuggy formations in a Mexican offshore field. Besides heterogeneity associated to these carbonated formations, vug spatial distribution is an important issue since hydrocarbon storage and deliverability to the wells is highly controlled by vugs density and connectivity. From computed tomography images, exhaustive 3D statistics are derived to build 3D stochastic models of those vuggy formations. Multiple point statistics simulated annealing and sequential indicator simulation based on kriging are used to model vugs geometry. The results indicate that both approaches honor the target statistics, and visual inspection of such images confirm good reproduction of connectivity. Further, it is shown that computer performances are different with simulated annealing being the most demanding. Although stochastic images from indicator kriging can be used as initial images for simulated annealing, it is demonstrated that few value is added by imposing multipoint statistics in the framework of vugs modeling. Therefore, it seems that stochastic simulation based on indicator kriging can build, with an acceptable computer cost and good reproduction, 3D images of vuggy formations.
Heavy Oil Solution Gas Drive in the Venezuelan Orinoco Belt: Laboratory Experiments and Field Simulation
Authors: Andarcia L. , Kamp A. M. , Vaca P. 
Published: December 2007

Abstract
The Venezuelan Orinoco Belt heavy oil reservoirs have been subject to research over recent years with respect to their possible anomalous production behavior. High recovery factors and high initial production rates are expected, which is not predicted using conventional characterization and simulation practices. Heavy Oil reservoirs with this behavior are referred to as foamy oil reservoirs.
We present laboratory experiments that can be used to obtain predictions on the production behavior of foamy oil reservoirs. These experiments were used to obtain relative permeability end-points. The effect of confinement pressure is shown, as depletion completed with an overburden stress shows a much higher recovery and critical gas saturation than the depletion without stress.
Preliminary reservoir simulations have been carried out for an area of the Orinoco belt with 7-8 years of production history, using the obtained relative permeability end-points. The match of the oil production rate and gas/oil ratio curves is presented. It is shown that an increase of gas-oil ratio (GOR) in the field could not be predicted with the laboratory-derived relative permeability end-points. This discrepancy may be the result of too coarse a simulation grid in the region of the well bore or may just highlight the difficulty in scaling laboratory measurements to the field-scale. The implications for field-scale simulation have not been fully explored.
Computer Simulation of Formation Damage Resulting From Thermal Recovery
Authors: Moore C. H. 
Published: December 2007

Abstract
The thermal recovery of heavy oil and bitumen from cool reservoirs via the injection of steam and hot fluids results in geochemical systems that are far from equilibrium. As a result, mineral and other solid grains in the reservoir may react with the injected fluid. These reactions often result in the dissolution of preexisting minerals and the formation of new ones. The types of minerals that form and their distribution in the reservoir may significantly impact reservoir quality, even to the point of blocking production.
If such deleterious phenomena occur, they can be irreversible. Consequently, it is prudent, when exploiting reservoirs with certain types of lithologies, to try and predict whether or not such formation damage is likely to occur. Computer simulations are the main tool for making such predictions.
This paper is intended to acquaint the reader with the basic type of analysis that can be done using a coupled flow/reaction geochemical computer code such as REACTRAN. Two basic reservoir types are used as examples, a carbonate reservoir and an immature sandstone reservoir. Two somewhat different lithologies for each reservoir type are used in the examples.
The examples show that different kinds of formation damage may take place. These include porosity gain that may lead to collapse, the formation of mineral fines from precipitation that may lead to fines migration problems, and the formation of clays and clay-like minerals that may occlude permeability.
Evaluation of IOR Methods for the Boscán Field
Authors: Kumar Mridul , Sahni Akshay , Alvarez J. M. , Heny C. , Vaca P. , Hoadley S. F. , Portillo M. 
Published: December 2007

Abstract
Chevron and Pdvsa-Intevep jointly conducted an evaluation of improved oil recovery (IOR) opportunities for the Boscán field to increase oil recovery and to help maintain future production rate. The shallower, northern area of the field was the target of this evaluation. Based on process screening results of Phase I, steam injection, waterflooding, and diluent/solvent injection were selected for a more detailed evaluation in Phase II.
During Phase II, fine-grid, geological models were built for the northern part of the field. In addition, laboratory experiments were conducted to obtain necessary data. The geologic model and input data were first validated using primary production data from representative wells. Numerical simulation studies for steam injection and waterflooding were conducted on three different segments to capture geologic variability. Effects of operating conditions and important uncertainties of input parameters on production forecast were obtained.
Results show that IOR processes have significant upside oil recovery potential. However, considerably smaller well spacing (well spacing of 290-m or pattern spacing of 54-acre or less) will be needed for floods. Only cyclic process can work at current spacing. Steamflooding results in the highest recovery (up to 43% OOIP). Cyclic steaming provides opportunity for accelerated recovery prior to steamflooding. Laboratory diluent injection appears promising but needs further evaluation.
New Thermal Recovery Technology and Technology Transfer for Successful Heavy Oil Development
Authors: Greaser Gary R. , Ortiz J. Raul 
Published: December 2007

Abstract
Continuous development and rapid deployment of new thermal technologies are critically important in the quest to make heavy oil projects cost competitive. Worldwide heavy oil deposits are abundant, but conventional development schemes may not be financially competitive. Currently, oil companies have a multitude of new investment opportunities, which further stresses required funds available for the continued development of new and existing heavy oil assets. How can heavy oil assets compete financially? New, cost effective technologies must be developed and deployed to improve the margins of heavy oil assets. An effective partnership must be maintained between the technology developers and the technology users to ensure a smooth transition from concept to field test to commercial application. The alignment of technology development to the real business needs is essential. This paper reviews a portfolio of new heavy oil technologies that Texaco is pursuing alone and in partnership with other companies. The processes used to assure business alignment, technology transfer, and deployment are also discussed. The heavy oil and thermal technology development portfolio includes novel steam generation, improved steam delivery (measurement and distribution), and aggressive heat management projects. These new surface and sub-surface heavy oil technologies will be discussed relative to the potential impact that they could have on several existing and new heavy oil fields.