bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Numerical Analysis of Mud Filtration for a Well with a Finite-Conductivity Vertical Fracture: Based on Convection-Dispersion Filtrate Transport
Authors: Pordel Shahri M. , Mosleh Tehrani M , Namvar M. 
Published: July 2011

Abstract
Most of the drilled wells are conducted on acidizing in order to eliminate the permeability reduction due to mud filtration. This type of formation damage is more sever in naturally fractured wells due to the high conductivity of fracture. If the radius of the damage due to lost circulation of drilling fluid is determined, the volume of acid needed to conduct any acid job could be calculated. Also, prediction of the near-wellbore conditions, such as mud filtrate radius, is important for accurate interpretation of the well-logs used for measuring and monitoring the properties of the near-wellbore formations. In this paper a mathematical model is developed to investigate the amount of mud filtration during drilling operation in a well with a finite conductivity vertical fracture in an infinite slab reservoir. Convection-dispersion filtrate transport model is developed in which the drilling mud can be mixed with the formation fluid. A systematic step-by-step procedure illustrating the methodology of the proposed model for the analysis of mud filtration in a finite conductivity fractured well is presented. This model is formulated for linear flow in both fracture and matrix. The effect of the filter cake is simulated by means of an empirically decaying filter rate equation. The developed model is solved by numerical analysis. The consistency of the numerical solution is checked and the best situation is considered. The sensitive analysis has been done on all the parameters of the model and the effect of each parameter such as wellbore pressure, fracture permeability, fracture diffusion coefficient, matrix permeability, matrix diffusion coefficient, matrix porosity, viscosity, constants related to the filter cake formation and fracture width on the amount of filtration are investigated. By means of the proposed model, the mud filtration can be plotted against position in both fracture and matrix for different wellbore and reservoir properties. The position in the fracture and matrix at which the curve of concentration reaches zero could be considered to represent skin radius. This radius could be used for the determination of the acid volume which is needed for the acidizing operation. Also, this model is a useful tool for accurate interpretation of the resistivity profiles which are essential for the development of efficient well-log interpretation.
Modeling of Meter Factors for Effective Oil Accounting during Proving and Calibration of On-line Meters in Custody Transfer Units
Authors: Bassey Akong , Dosunmu Adewale , Amiebibama Joseph , Agbor Etta 
Published: July 2011

Abstract
Oil metering is the determination of the quality and quantity of well effluent produced, transferred, delivered or sold. This volume of oil must be measured accurately since it determines the amount paid for oil and gas transaction, royalties and taxes. Measurement of oil and gas, purchases and deliveries is made on a flowing well effluent stream. Hence, flow measurement is paramount in the oil and gas industry. Engineers always check to ensure that the well effluent production rate corresponds with a good reservoir management by flowing the oil and gas well through a choke size that would prevent gas cuspling; this is usually done by monitoring the hydrocarbon well stream flow rate at the flow station after well stream fluid separation. To ensure that the volumetric and flow rate readings obtained from meters are accurate and do not impact negatively on the overall economics and operation of a company, meters have to be proved regularly. This is a procedure required to determine the relationship between the true volumes of well effluent measured by a meter and the volume indicated by the meter. For example an error of only 1.0 % in the measurement of well effluent in a pipeline delivering 300MMcfd of gas and 400 barrels of oil at $1million per year can lead to many losses to either the seller or to the purchaser. Therefore, this study is aimed at modeling a meter factor for proving and calibration of on-line meters. . The developed meter factor model will enhance effective meter factor computation to compensate for temperature, pressure and volume of well effluent and steel in custody transfer units(CTU) based on API standard. inaccurate measurement of well effluent will exposed a company not only to the risk of large financial losses, but also manpower constraints.
Monetizing Stranded Reserves: The Role of Floating LNG
Authors: Nwaoha Chikezie 
Published: July 2011

Abstract
As the world's population grows and economies develop, the demand for energy will continue to grow significantly. This increased demand is also being underpinned by the desire for cleaner source of energy to minimize impact on the environment. The International Energy Agency and many others predict that the world's total energy demand will grow by about 35% in 2030 from today's level. Crude Oil and Natural gas are estimated to account for nearly 60% of total energy supply through 2030 for a number of reasons. The growing attractiveness of global Natural gas development also supports the general consensus and forecast that Natural gas will overtake oil towards the middle of the century as a primary energy source. Natural gas is also being used in a variety of processes as feedstock, fuel, etc. Its contribution to world energy resources is growing leading to the concept that it is a bridge to the ultimate hydrogen economy. The flexibility brought about by growing importance of liquefied natural gas, LNG, is also changing the dynamics of the natural gas supply and demand equilibrium. The massive growth in global LNG demand and the challenging supply constraints are putting pressure on the industry to think of more innovative ways to harness and monetize stranded gas fields in a cost-effective and creative manner. Some schools of thought believe that as much as 40% or more of the total global gas reserves is stranded and needs to be brought to market creatively. Such stranded gas resources, found in deep offshore acreages and such remote locations are typically isolated from onshore processing facilities and may not be profitably developed by conventional means. This creates the niche application for the Floating LNG technology as creative way of monetizing the resources. The majority of the world's stranded gas reserves are located in the CIS (30%) and the Middle East (25%). Africa was third, with 16% of the reserves, and was followed by the Far East (13%), Latin America (13%), Alaska (5%) and Australasia (3%). The top-five countries for stranded gas are Russia, Iran, Nigeria, Saudi Arabia, and the Alaskan North Slope in the U.S (http://energy.ihs.com/NR/rdonlyres/8A35BF8A-0CD3-4A13-9E26 1BB5B977C97E/0/stranded_gas_economics.pdf). This paper seeks to identify and emphasize the role and contribution of floating LNG as a more effective way of having access to and monetizing stranded reserves and associated gas, in an environmentally responsible manner safely. This paper also reviews the current status of FLNG projects, to highlight the technical and commercial obstacles that still confront them, and offer insight into how these obstacles might be overcome.
New Method of Generating Approximation Profile of Highly Noisy Wireline Logs through Utilizing Wavelet Non-Parametric Regression
Authors: Shahvar M. B. , Kharrat R. , Dashtbesh Badounak N. 
Published: July 2011

Abstract
Although highly advanced technologies and instruments provide different types of wireline logs data in an oil field today, geologists and petrophysists are faced with the problem of interpreting highly noisy large datasets. In order not to waste the high expenses spent for applying new technologies, effective de-noising techniques are required to lead to the exact interpretation of the data. In the following study that utilizes wireline logs datasets containing more than 30000 data points of an oil field in Iran, new approach of approximating general trend of the data concealed in a heavy noise against depth is applied. In this new method at first the whole profile of the data and their associated depths are transformed as a two vector matrix to a time-scale space of discrete wavelet domain. By reducing the general regression problem to a fixed-design model, decomposing the signal, reconstructing the function that exists between the two vectors and finally re-scaling the resulting function, wavelet provides the general trend of the profile which is thoroughly free of noise and have all the critical information remained within. This advanced technique of reconstructing the wireline log profile is useful where numbers of the data points are large or the signal is heavily overlaid by noises. In addition to logs data, other signals such as seismic traces can be analyzed using this approach too.
Oil Exploitation, Local Economy and Conflict in the Oil-Bearing Areas of Nigeria's Niger Delta
Authors: Babatunde Abosede Omowumi 
Published: July 2011

Abstract
Half of the world's mineral dependent states are concentrated in Sub-Sahara Africa. However, these countries lie at the lowest rank in comparative statistics on human development. Some African countries, for example, Botswana and South Africa, have shown ample evidence that mineral wealth can be turned into concrete development benefit if properly managed. Nigeria, sub-Sahara Africa's largest oil producer is a classic illustration of natural resources as a developmental trap. Oil wealth enriches Nigeria as a country, but it also aggravates the poverty and deprivation in the oil-bearing areas of the Niger Delta. Oil-bearing areas have been facing social and ecological risks which culminated in the violence that have characterized the region. Literature has highlighted the consequences of oil exploitation such as violent communal crisis, youth restiveness, government and oil-companies’ brutal repression. However, the actual nature of the effect of oil exploitation on the local economy has not been established. Thus, this study examines the impact of oil exploitation on the local economy and conflict in the oil-bearing areas of the Nigeria's Niger Delta. This study made use of qualitative data obtained through in-depth interviews with key informants and Focus Group Discussion (FGD). Oil-related activities have affected the people's livelihoods, food security, personal security, physical and mental health. Oil exploitation through environmental degradation depleted fishing and farming output, resulting in the subsequent loss of income base, thereby accentuating poverty, which in turn created divisive tendencies leading to endemic social conflict. Any effort to eradicate poverty in the oil-bearing areas must seek to revive and revitalize the traditional economic activities. Providing viable employment opportunities for the people, particularly the youth, and channelling their energies into the development of sustained livelihoods as well as natural resource management activities can reduce current tensions and conflict in the oil-bearing areas of the Niger Delta, Nigeria.
Option for Adoption of Hydrogen or Natural Gas With Emulsified Biodiesel for Pilot Injection in Dual-Fuel Operation of Diesel Engines
Authors: Bob-Manuel K. D. , Crookes R. J. , Korakianitis T. , Namasivayam A. M. 
Published: July 2011

Abstract
The research on the use of alternative or sustainable fuel in diesel engine operation for transportation and power plant has been intensified in the past few years to achieve improved performance and friendly environment. In this study, an emulsified biodiesel (rapeseed methyl ester – RME) was used for pilot injection in a natural gas and hydrogen dual-fuelled compression ignition (CI) engine to investigate the performance and levels of exhaust emissions under steady state conditions. Generally operation with natural gas dual-fuel using emulsified RME fuel pilot injection reduced NOx emissions while similar operation with hydrogen increases the NOx. The use of hydrogen as fuel in transportation and power plant operation will contribute mainly in the reduction of CO2 and hence greenhouse effect (climate change) on the environment.
Properly Use Effect of Capillary Number on Residual Oil Saturation
Authors: Bashiri A. , Kasiri N. 
Published: July 2011

Abstract
Heterogeneity of the hydrocarbon reservoirs can be defined in pore level or macroscopic scale. Pore level heterogeneity such as pore size and structure controls the quantity of hydrocarbon left (residual saturation) during production, whereas macroscopic heterogeneity determines zones that injected fluid sweeps (Franklin, 1994). During simulation of a reservoir, macroscopic heterogeneity is represented by assigning different rock properties (e.g. permeability and porosity) for different simulation grid blocks. However, due to complex nature of pore entrapment mechanisms, it is only possible to represent pore scale heterogeneity with empirical correlations. Capillary Desaturation Curve (CDC) is a suitable correlation that links residual hydrocarbon saturation to physical properties of a given reservoir in pore scale. Therefore, accurate representation of CDC pattern can be critical for Improved Oil Recovery (IOR) processes evaluation as pore information is used as the basis for residual saturation prediction. Application of CDC data for reservoir simulation and IOR has been reviewed here accordingly.
Properties of Salt Formations Essential for Modeling Instabilities While Drilling
Authors: Omojuwa Emmanuel O. , Osisanya Sameul O. , Ahmed Ramadan 
Published: July 2011

Abstract
Taking drilling beyond the continental shelves further into the great depths of water leaves the drilling industry with no option of avoiding reservoirs lying beneath great masses of salt formations. Presently, salt formations trap rich reservoirs in Brazil, West Africa, Gulf of Mexico, North Sea and off the coasts of eastern Canada. The discovery of producible reserves beneath vast, thick sheets of salt formations challenges the regular drilling and completion practices, making every operation a unique experience. Drilling through salt formations can become successful only when the essential properties of salt formations (e.g. halites) that may cause instability are clearly understood.
Instabilities in salt formations arise from the ability of the salt to flow under loading conditions (creep) and the ability to dissolve at certain conditions and elevated temperatures (solubility). This paper presents the checklist of essential contributing properties that must be accounted for in modeling creep- and solubility-induced instabilities in salt formations. These properties are classified under the physical, mechanical and structural subheadings, and the values of these properties for deepwater subsalt formations are provided for use in creep and solubility predictive models. This paper is based on well design approach i.e. begin the planning from the depth of location of the salt formation, that is, the salt formation becomes the starting point, working backwards to the surface and forward to the target reservoir. Temperature response, melting point, solubility, thermal conductivity, octahedral shear stress, solubility, creep, anisotropy, density, friction, hardness, strength, fracture gradient, permeability are some of the properties analyzed in this paper and their influencing parameters in order to develop an all-encompassing model for used in drilling through alt formations.
In addition, this paper examines the application of the essential properties to the geo-mechanical studies of salt formations. The case study of this research is the design of an exploratory well in the Gulf of Mexico where properties of the salt formations: crystal structures, salt dissolution, creep, temperature and pressure response determined the drilling fluid composition, cement slurry, and casing design.
Reconciling and Improving the Volumetrics of Nigerian Heavy Oil and Bitumen Resources
Authors: Lawal Kazeem A. 
Published: July 2011

Abstract
Despite being penetrated by over 100 wells, and more than a century of studies, the in-place and recoverable volumes of oil resources within Nigeria's bituminous belt are still inconclusive. Noteworthy is the misleading appropriation of "reserves" to the deposit. While there is an obvious motivation to improve the current situation, credibility requires that such efforts are premised on a combination of reliable dataset and robust method of study.
This article is an attempt at reconciling and improving current estimates of the hydrocarbon potentials of the Nigerian bituminous belt. It reviews and integrates numerous datasets on the belt. Reasonable assumptions, empirical correlations and analogue information are used to mitigate identified data gaps while recognising uncertainties. With estimated input data and associated uncertainties, deterministic and probabilistic techniques are employed for robust volumetrics. Unlike previous studies, we consider solution gas.
Using performances of some proven exploitation technologies in provinces of comparable reservoir and fluid characteristics as Nigeria's, we make reasonable estimates of recovery factors, and establish cumulative distribution curves for recoverable (not reserves) volumes of discovered bitumen, heavy oil and oil shale deposits, including the dissolved gas content.
From the analyses, we estimate 71, 207 and 415 billion barrels as the P90, P50 and P10 stock-tank oil in-place volumes, respectively. Corresponding solution-gas quantities are 1.4, 5.0, and 13.6 Tscf, respectively. Compared to current official record of about 43 billion barrels, which does not account for the field-proven solution gas, potentials of Nigeria's bituminous belt may be significantly underestimated at present. Although the volumetric ranges in this study reflect the relative magnitude and impact of uncertainties, sensitivity analysis indicates that reservoir extent and thickness as well as solution gas-oil ratio are the main uncertainties. Consequently, a key objective of future appraisal programs should be to narrow the current range of (static) uncertainties.
Revisit Material Balance Equation for Natually Fractured Reservoirs
Authors: Bashiri A. , Kasiri N. 
Published: July 2011

Abstract
The material balance equation (MBE), as a zero-dimensional model (with some assumption such as uniform pressure, PVT data and temperature within a given reservoir), has been used to identify some critical items such as Original Hydrocarbon in Place (OHIP), relative volume of initial gas cap, aquifer behavior and different depletion mechanism indexes within a given reservoir (Pletcher, 2002). Conventional MBE (CMBE) is based on the black oil concept that can limit its use for volatile oil and gas-condensate reservoirs. Furthermore, heterogeneity of the naturally fractured reservoir (NFR) as a dual porosity system can impose some restriction on CMBE application. A modified MBE is proposed here for use in fractured or gas-condensate reservoirs with some example for its application.
Sedimentary Controls on Porosity and Permeability in Deepwater Turbidites
Authors: Njoku Chukwueke , Pirmez Carlos 
Published: July 2011

Abstract
Knowledge of the sedimentary controls on porosity and permeability is important in the exploration and production of oil and gas in various depositional settings. In deepwater reservoirs this is even more important because of the high cost of development wells. Few studies of porosity and permeability in deepwater reservoirs are available. We report on the main controls on porosity and permeability of deepwater reservoirs using core plug samples from several wells in Shell's deepwater portfolio. Results show that grain size control on permeability and sorting control on porosity and permeability are well reflected in the turbidite and debrite facies.
Simulation of CO2 Enhanced Oil Recovery in Heterogeneous Models
Authors: Biu Victor T. 
Published: July 2011

Abstract
In mature and depleted oil field, it has been discovered that significant amount of oil is left unswept. The ability to evaluate the remaining oil depends on the understanding of the heterogeneity of the reservoir most especially when there is plan for tertiary flooding such as Carbon dioxide EOR
This work focuses on the impact of geological structure on the sweep efficiency and reservoir oil recovery in a small-scale heterogeneous model using CO2 injection. Three models which include; homogeneous, layer and laminated reservoir models with sedimentary structures were simulated with ten hydrocarbon fluid component.
Results from the simulation of the three geological models indicate channeling effect in a laminated model which results to more oil been trapped in the low permeability laminae, thus lower oil recovery. It was discovered that the CO2 rich oil zone forms a mobile displacement front in the 2-D x-y model that enhances the sweep efficiency in all layer and homogeneous models review. At reservoir pressure below saturated pressure, increase in oil saturation close to the injector was noticed in the homogeneous model due to gravitational effect. This could be attributed to the increase in density of the dissolved CO2 in oil resulting to bypassed oil. Result also discovered that higher temperature and pressure, irrespective of the nature of the reservoir system has significant effect on oil recovery during CO2 flooding.
Specific Heat Capacity of Natural Gas; Expressed as a Function of Its Specific gravity and Temperature
Authors: Adewale Kareem Lateef , James Omeke 
Published: July 2011

Abstract
Natural gas engineering entails production, processing, storage and transportation of natural gas. A good handling of the gas requires a sophisticated understanding of how its density, compressibility, pseudo-pressure, and specific heat capacity varies with the gas condition. While petroleum & gas journals and a host of scholastic materials have presented varieties of means to evaluate other properties, they neglected or underscored the need for same for specific heat capacity of natural gas. The only available mathematical relation for this property only predicts its value at 1500F- not at other temperatures.
Samples of natural gas collected from Bell field, Sabine field, Bacon lime and paradox formation were used as data source. The variation of the respective specific heat capacity of the components and the effect of the composition on the specific gravity and overall specific heat capacity of the gas was taken into consideration giving rise to a robust correlation that reads in the individual composition of the gas, its density and temperature to generate the specific heat capacity of the gas.
The result yielded 98.3% accurate result compared to the method of isentropic coefficient at 150°F and an average error of 0.3% within a range of 491°R to 2740°R.
The benefit of this work is that it provides a means of dealing with situation where the heat transferred into or out of a natural gas system is to be calculated over a wide range of temperature as it allows the specific heat to be expressed as an integratable function of temperature other than the isentropic coefficient method which only gives a constant value for a variable that is not constant.