bluuebunny/crossref_metadata_2025_split huggingface dataset:
Probabilistic Risk Analysis Applied to the Evaluation of Alternatives for Management and/ or Exclusion of Sand
Authors: Jaimes M. G. , Sanabria F. E. , Quintero Y. A. , Contreras G. Y. , Martin D. P. 
Published: April 2012

Abstract
Sand production is a critical problem that causes the industry spending over $3.0 Billion U.S. per year (70% of the wells worldwide have this problem). To mitigate the impact, many operators choose the option of deploying technologies to exclude the sand, and usually reduce the benefits for decrease a risk not quantified.
Currently the reservoirs trending to sand production contain an increasing percentage of the world's hydrocarbon reserves. Many of the wells that exploit these resources are producing beyond the limits of their originally estimated useful life, which can result in weak formations. Consequently, it is required being more demanding in the profit margins of the projects of Management and / or sand control achieved at these reservoirs, so it requires a probabilistic risk analysis (PRA) in them, taking into account that the risk and uncertainty are two factors that are often present. This analysis facilitates decision making and allows determine the best Completion and production strategy of the formations sensitive at sand production.
Based on the above, this work focuses on developing a methodology for probabilistic risk analysis to evaluate management alternatives and / or exclusion of sand using Monte Carlo simulation. The methodology includes six phases: (1) Selection of alternatives to evaluate and definition of the conditions of production of each one, (2) Structuring the deterministic model of each alternative (3) identification of most impacting variables on the level of production of each alternative and determination of its range of typical behavior (4) Estimation of probability distributions of production for each variable, (5) Monte Carlo simulation for risk assessment of each alternative and selecting the best choice.
The methodology was applied to evaluate management alternatives and / or exclusion of sand in the formations sensitive to sand production of the fields: Lisama, Llanito, Galan, Brisas and Yarigui-Cantagallo in Colombia and was compared with the results of the evaluation when using deterministic models. In this paper is present the Application cases in the wells: Lisama 171 and Yarigui 168.
Finally, the main findings, conclusions and recommendations obtained in this study are shown.
High Energy Gas Fracturing: A Technique of Hydraulic Prefracturing To Reduce the Pressure Losses by Friction in the Near Wellbore - A Colombian Field Application
Authors: Jaimes M. G. , Castillo R. D. , Mendoza S. A. 
Published: April 2012

Abstract
One adequate management and optimization of mature fields requires the use of techniques, methodologies, technologies and analysis of the behavior of the wells to generate recommendations of production optimization with the highest probability of exit.
One alternative that today has proven successful and is widely applied worldwide to maximize the profitability of the fields, consists in the implementation of hydraulic fracturing jobs, to improve the flow capacity of the wells, which is achieved to go through the formation damage, speeds up the reserves, etc. However, one of the main difficulties of hydraulic fracturing, are the high friction pressure losses in the near wellbore (NWBF), which require high pressures to break the formation and equipment of higher power in surface. This means work over more expensive and with a lower economic profitability.
An evaluation of new technologies, allowed the identification of the alternative called High Energy Gas Fracturing (HEGF), as a pre-fracturing technique to reduce pressure losses by friction in the near wellbore (NWBF). HEGF is a perforating technique with propellants, which not detonate, but they blaze with high heat, but unexploded (deflagrate), releasing a high energy gas that reaches a sufficient pressure pulse (10,000 to 50,000 psi) and combustion time (5 – 30 milliseconds) that creates fractures in all radial directions at short distance.
For different operational areas of the Colombian state owned oil company, Ecopetrol SA, was performed an evaluation of pressure loss by friction in the near wellbore (NWBF), during hydraulic fracturing operations that have been executed. This allowed to make recommendations to implement HEGF and thus optimize the hydraulic fracturing operations. This paper presents the results of the assessment in the fields Apiay, Austral, Gavan, Suria and Yarigui.
Finally, the main findings, conclusions, recommendations and field results obtained in this study are shown.
Feasibility of High Pressure Air Injection in Heterogeneous Light Oil Reservoir by Thermal Simulation
Authors: Shah Aarshavi , Modi Kaushal 
Published: April 2012

Abstract
HPAI in Light oil reservoirs have gained a success nowadays in the field. Air injection in light oil is decided on the basis of in which phase of the life reservoir stands. The main aim of this EOR method is to strip out the Lighter Hydrocarbons from the residual Heavy Fractions and also to act as a pressurizing agent as from conventional heavy oil reservoirs to reduce the viscosity and removing the residual oil saturation. The factors affecting the HPAI are Geology and the Geological structure and the reaction kinetics parameters like reaction frequency, enthalpy, activation energy and the mode of reaction i.e. Low Temperature Oxidation (LTO) and High Temperature Oxidation (HTO). In this paper, the laboratory procedures, for the Air injections have been calculated i.e. the velocity of the combustion front, temperature profiles and the ignition time of the initiation of reaction. Simulation of combustion tube experiment has been carried out and expanded to the block model in CMG STARS. The tuning of the reaction parameters is to generate the temperature profile of the twelve zones of the combustion tube experiment. History matching with the data generated in simulation and the outcomes of the laboratory experiment is performed. The block model with five spot inverted pattern predicts the variation of oil saturation, temperature, oil cut, water cut, cumulative fluid rates with time. The conclusion from this simulation is the feasibility of High Pressure Air injection processes in Light Oil Reservoir and predicting the future performance in the reservoir. The results from this simulation were that the clay particles affect the reaction kinetics in the Light Oil and the increment in the recovery is about 20 % because of HPAI.
Novel Method for Characterizing Single-phase Polymer Flooding
Authors: Sun Wenjie , Peking U. , Li Fen , Qu Yantao , Yang Yaozhong , Li Kewen 
Published: April 2012

Abstract
Polymer flooding has been used to enhance oil production and reduce water cut for a long time. However there are still many fundamental challenges in characterizing the multi-phase fluid flow, even the single-phase fluid flow, associated with polymer flooding. For example, it is difficult to measure and calculate two-phase polymer solution/oil relative permeability. One of the difficulties comes from the non-Newtonian and time-dependent properties of polymer solutions; another comes from the change in absolute permeability caused by the adsorption of polymer on rock surfaces. Almost all of the methods for computing relative permeability are based on the assumption that the absolute permeability is constant. It will be helpful to further understand the mechanisms and develop more reliable methods for calculating two-phase polymer solution/oil relative permeability by investigating the single-phase polymer flooding more profoundly. In this study, a new method has been developed to calculate the pseudo permeability during single-phase polymer flooding. The non-Newtonian property of the polymer solutions was considered in the proposed method. A series of polymer flooding experiments using different concentrations of polymers were designed and conducted to study the single-phase flow of polymer solution in rocks with different permeabilities. The values of the pseudo permeability of single-phase polymer flooding were then calculated using the new method. It has been found that the relationships between the pseudo permeability and the reciprocal of shear rate were linear. The pseudo polymer flooding permeability extrapolated at the infinite shear rate was close to the brine flush permeability after polymer injections in most of the cases.
Economic and Technical Feasibility Analysis of the Use of a Water Base Drilling Fluid at Levas Field, Dacion Production Unit, San Tome District Ayacucho Division - Venezuela
Authors: Ras Nael Abo , Graterol Jenny , Ruiz Fernando 
Published: April 2012

Abstract
The development of the Levas field began in 1952, by drilling vertical wells using a water-based drilling fluid, however, from 1998 when the aggressive drilling of deviated wells began, also the operational problems started in the middle section, problems such as tight hole, drag, hole instability, stuck pipe, and others. In 2002, the company decided to switch to oil-based mud to reduce and control the incidence of those inconveniences.
PDVSA Services San Tome, began searching for a special drilling fluid to replace the existing, due to high demand of the main component of the oil-base drilling fluid (Vassa), and its low supply due, and more important the high cost and environmental difficulties to treat and dispose this kind of drilling fluid and the cuttings. This study evaluated four sets of high performance water-based drilling fluids, to start a new development stage for drilling deviated wells at the Levas Field.
To determinate the technical feasibility, some studies were made, first the physical properties, such as: rheology, filtration, solids percentage in the system, and others, were evaluated to make a comparative analysis to find out which water-base drilling fluid had the best performance considering the geological and operational conditions of the field.
Also the mineralogy (clay minerals) of the field was determinate through the X-ray diffraction test, which concluded that the predominant mineral of the field was kaolinite. This clay has a low CEC value that means it has a high dispersion capacity. This result allowed to determinate one of causes of the hole instability in the middle section of the deviate wells. Additionally, the Dynamic Linear Swell test was made to determinate the inhibitory capacity of each water-base drilling systems with the clays from the formation and bentonite, beside the clay dispersion test evaluated evaluate the capacity of each high performance drilling fluid systems to maintain the integrity of the body shale and cuttings.
Finally, the cost analysis allowed evaluating the economic feasibility of each drilling fluid system. After analyzed the various results, we concluded that the drilling fluid trading system number one had the best cost benefit to drill deviated wells in Levas Field.
Transient Modeling of a Subsea Pumping Module Using an ESP
Authors: Teixeira V. F. , Gessner T. R. , Shigueoka I. T. 
Published: April 2012

Abstract
In the pursuit of more productivity, Petrobras has been using more and more ESPs (Electric Submersible Pumps) on its subsea wells, especially on heavy oil fields, where the gas-lift is not as attractive as that method. Those scenarios are very common in the Campos Basin, particularly at the Jubarte-Cachalote Asset, where the oil has an average API gravity below 20°.
However, since the ESP MTTF (Mean Time To Failure) is around two years, Petrobras has proposed new technologies that can reduce the intervention time and costs for this method. The Subsea Pumping Module (MOBO) is an excellent alternative for it. The system consists of an ESP that is installed on a caisson located around two hundred meters from the production wellhead. This module allows not only a faster intervention for pump exchange after a failure when compared to the conventional in well ESP, but also accept the ESP installation without interrupting production (by using gas-lift as a contingence, bypassing the MOBO).
On the other hand, the Pumping Module has inherent constructive instabilities. The geometry of the system forces a downward annular flow, which causes the partial gas-liquid separation of the incoming multiphase production. This separation may generate not only instabilities, but also an excessive gas fraction at the pump inlet, that may cause the phenomenon known as gas-lock, impairing the pump performance and even causing its failure.
Thus, this study intends to characterize the hydrodynamic behavior of the flow in the Pumping Module, through the use of a multiphase transient approach. This model have been developed using a multiphase transient simulator and it has been validated through an extensive comparison with a producing well. To carry it out, data were collected from online instrumentation and production tests to be used as validation parameters. A good correlation between model results and production information was obtained, helping Petrobras to predict unexpected behavior of new wells that will produce using the MOBO. The validated modelling proved to be an useful tool for flow assurance studies for this production setup.
Micro-tomographic Characterization of Dissolution-induced Local Porosity Changes including Fines Migration in Carbonate Rock
Authors: Qajar Jafar , Francois Nicolas , Arns Christoph H. 
Published: April 2012

Abstract
The microstructure of carbonate rocks experiences substantial changes under reactive processes, in particular chemical dissolution and deposition including dissolution-released fines migration occurring during acidizing. A better understanding of such changes at the pore scale and their influences on rock properties is of great value for the effective design and implementation of reactive processes in carbonate reservoirs. In this work, we demonstrate the use of X-ray micro-computed tomography (μ-CT) to quantitatively investigate the local porosity changes in a meso/microporous carbonate core sample during chemical dissolution. A reactive flooding experiment in a core sample by a non-acidic solution is designed such that changes in pore space from before to after the reactant injection could be imaged in exactly the same locations using μ-CT at resolution of less than 5μm. A methodology based on three-phase segmentation and 2D intensity histograms of images is used to quantify distributions of the evolution of each image voxel. This technique allows the incorporation of microporosity into the calculation of the evolution regions including the migration of fines in order to accurately quantify the evolution scenarios. The µ-CT images reveal a quasi-uniform dissolution pattern and allow characterizing the accompanying migration of fines within the core sample. 3D pore networks are derived from the image data, which quantify changes in network structure and the pore geometry. 2D histograms of image intensity derived from the pre- and post-dissolution images quantitatively show how macro and micropores are enlarged by dissolution close to the inlet while deposition of fines mainly occurs in pores far from the inlet boundary. These results can explain why permeability of the sample initially decreases and then increases as injection time increases. Based on the spatially resolved voxel evolution scenarios, pore surface area between each region is computed. This allows calculation of local distribution of reactive surface area which in turn will assist in the prediction of local reaction rates in reactive flow simulators.
Economic and Social Development of Angola Because of Petroleum Exploration (Revisited)
Authors: do Carmo D. Fernandes , Amoreira M. Gonzalez , Bone R. Bröker 
Published: April 2012

Abstract
Angola currently represents one of the largest economies in Sub-Saharan Africa. The same has achieved great economic growth, derived mainly from its mineral wealth. However, is still part of the low human development group with regard to the HDI, with 68% of the population living below the poverty line and 15% living in extreme poverty (second bulletin No. IFAD/23/08) with a consequent increasing rate of social inequality. The evaluation of the exploration and production (E&P) of oil in a country is essential for there to be a better use of the commodity for the purpose of economic growth and development. This article aims to explain the conditions, both social and economic consequences of Angola, to know whether the country has gained in quality of life with the national oil and gas activity. The variables to be examined are: the Human Development Index (HDI), Human Poverty Index (HPI), Infant Mortality Rate, Gross Domestic Product (GDP), Indexes of Health and Demographic Trends. In what concerns the variables in the oil sector, it is observed: the daily production and proved reserves of oil and natural gas and oil GDP. This juxtaposition of social and economic indices for the period 2004–2010 will evaluate the effects of the insertion of Angola's oil production and gas worldwide, as part of OPEC since 2007. From the analysis made in this article enables us to say that oil is not bringing the expected social development for the country as the income generated by oil still remains concentrated in few hands, and the civil organization of the main culprits behind it. The process of political reconstruction of the country was late, allowed the first presidential elections only in 2008, which ended up hindering the effective implementation of an effective social inclusion plan. Meanwhile, GDP per capita grows at relatively high rates. We know that Angola is presented on the world stage as a strong oil and gas power, yet the country still needs to rearrange themselves politically in order to create more jobs and income, which will ultimately improving the health, education and living conditions of citizens Angolans.
Combining Decline-Curve Analysis and Capacitance-Resistance Models To Understand and Predict the Behavior of a Mature Naturally Fractured Carbonate Reservoir Under Gas Injection
Authors: Salazar Martín , Gonzalez Hector , Matringe Sébastien , Castiñeira David 
Published: April 2012

Abstract
Capacitance-Resistance (CR) models have received renewed interest in the past few years as a fast alternative to reservoir simulation to model and predict complex water or gas floods in mature reservoirs. Using an analogy between reservoirs and electrical systems, CR models represent the interactions between wells through analytical solutions to an equivalent capacitor-resistor circuit.
CR models do not require a geologic model and can be built with only production and injection data. When modeling fields with numerous wells and a long history, traditional reservoir simulation workflows are extremely time-consuming. The simplicity of CR models make them extremely attractive to quickly model and predict the behavior of these complex reservoirs.
Current CR models are able to represent accurately the behavior of reservoirs under strong water or gas floods, where the injection is the main driving mechanism for production. In such cases, the production rates are strongly correlated to the injection rates and CR model are ideally suited to decipher these interactions.
However, most reservoirs start with a period of primary depletion or many are exploited under a weak injection strategy, for which CR models are not ideally suited. Here, we propose to combine decline-curve (DC) analysis with a CR model in order to solve this shortcoming. Using the superposition principle, the contribution of primary depletion to production is represented by DC and the contribution of injection is represented by the CR model.
After presenting the formulation and implementation of our DC-CR model, we demonstrate its performance on a deep naturally fractured carbonate reservoir under hydrocarbon gas and nitrogen injection. The reservoir has over 30 years of production history: 23 years of primary depletion and 8 years of gas and nitrogen injection. Using a one-year blind test, we demonstrate that the model is able to accurately predict the reservoir behavior.
Analytical Estimation of CO2 Storage Capacity in Depleted Oil and Gas Reservoirs Based on Thermodynamic State Functions
Authors: Valbuena Ernesto , Barrufet Maria , Falcone Gioia 
Published: April 2012

Abstract
Numerical simulation has been used, as common practice, to estimate the CO2 storage capacity in depleted reservoirs. However, this method is time consuming, expensive, and requires detailed input data. This investigation proposes an analytical method to estimate the ultimate CO2 storage in depleted oil and gas reservoirs by implementing a volume-constrained thermodynamic equation of state (EOS) given average reservoir pressure and fluid composition.
This method was implemented in an algorithm which allows fast and accurate estimations of final storage, which can be used to select target storage reservoirs and design the injection scheme and surface facilities. Impurities such as nitrogen and carbon monoxide, usually contained in power plant flue gases, are considered in the injection stream and can be handled correctly in the proposed algorithm by using their thermodynamic properties in the EOS.
Results from analytical method presented excellent agreement with those from reservoir simulation. Ultimate CO2 storage capacity was predicted with an average difference of 1.26 wt% between analytical and numerical methods; average oil, gas, and water saturations were also matched. Additionally, the analytical algorithm performed several orders of magnitude faster than numerical simulation, with an average of 5 seconds per run.
Simulation Study of Displacement Mechanisms in Microbial Improved Oil Recovery Experiments
Authors: Shabani-Afrapoli Mehdi , Crescente Christian , Li Shidong , Alipour Samaneh , Torsaeter Ole 
Published: April 2012

Abstract
Microbial Improved Oil Recovery (MIOR) processes use bacteria or their bioproducts to help mobilizing additional oil from the reservoir. The chemical and physical properties of the reservoir fluids and rock are changed during the MIOR process. An extensive investigation has been carried out at laboratory temperature with dodecane and an alkane oxidizing bacterium, Rhodococcus sp 094, suspended in brine to study potential recovery mechanisms involved in the MIOR process. Flooding experiments on Berea sandstone cores and flow visualization experiments within glass micromodels have shown the effects of bacteria on remaining oil saturation. The interfacial tension reduction, wettability alteration and selective plugging are recognized as important displacement mechanisms during the MIOR process. The objectives of this paper are to present the experimental results and to evaluate the driving mechanisms of MIOR by using two simulators. ECLIPSE is used to build a model based on core parameters for simulating the core flooding process. While, COMSOL Multiphysics models the two phases flow obtained experimentally at the pore scale within the micromodels. Simulation results are consistant with the experimental results and indicate that both tools are useful to solve the simulation problems of MIOR process. The obtained results address capability and inability of simulators to model the MIOR displacement mechanisms.