bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study of Wax Deposition in a Single Phase Sub-cooled Oil Pipelines
Authors: Adeyanju Olusiji A. , Oyekunle Layioye O. 
Published: July 2013

Abstract
The ability to determine the severity of wax deposition is an extremely important issue, particularly in the design and development of deepwater oilfields. Though much progress has been made in the last decades to better the understanding of this complex process, yet the ability to accurately account for all the factors that affect wax deposition are currently not in existence in the wax simulators used presently in the industries. In this study an experimental methodology constructed to simulate wax deposition process was employed to investigate the influence factors controlling paraffin wax deposition to the pipe wall surface (namely, inlet oil temperature, inlet coolant temperature, oil flow rate and the wax content). Series of tests were designed to determine the effects of these influence factors on the wax content in the deposit. The experimental results revealed that the amount of wax deposited initially increases with time, attained a maximum value and gradually erode off. Also it was discovered that the wax deposition decreases with flow rates and also with the temperature difference between the flowing oil and the pipe wall, when the oil temperature is above its Wax Appearance Temperature (WAT), while the reverse is the case when the oil temperature is below its WAT. The study also established that shear dispersion, defined as the movement of wax crystals towards the pipe wall as a result of the velocity variation along the radial direction during oil flow in the pipe ignored in most of the existing models used in the existing wax deposition commercial codes was found not to be inconsequential. The flow rate rather than the flow regime was also discovered to responsible for the shear stripping of wax deposit at the wall. This experimental observation will provide a reference point and an insight for further study on wax deposition in actual pipelines. This is particularly so for oil characterized by high wax content and high gel point temperature like those produced from most fields in Nigeria's Niger Delta.
Activated Carbon, a Possible Carbon Solution in Nigeria
Authors: Ike I. A. , Adjimah M. , Ike G. U. , Ezugwu C. 
Published: July 2013

Abstract
From heavy oil extraction in Canada, shale oil and gas production in the US and coal usage in China and India, energy successes are clearly linked to optimal utilization of available resources no matter how unconventional. In stark contrast, Nigeria's associated gas is continually flared and treated as a huge liability despite gas proven environmental advantage and heating efficiency in industrial and domestic processes. It is sad to note, for example, that the perennial flaring of gas in the Niger Delta has ever existed along side perennial kerosene scarcity all over Nigeria.
The main challenge with the utilization of associated gas in Nigeria is the low pressure and volume of the gas available at a particular producing station. Harnessing these low-pressured, scattered gas resources using conventional technologies will require expensive gathering, compression and transportation systems.
In this paper, the authors explore the potential contribution of activated carbon in gas utilization efforts in Nigeria. Activated carbon allows the adsorptive storage of natural gas at a relatively low pressure. The natural pressure of the produced gas may be sufficient or a low capacity compressor may be installed for this purpose. This could allow the setting up of small activated carbon adsorption units wherever gas is routinely flared in the Niger Delta. From an environmental and economic view point, this is a game changer as flaring is reduced and gas is made available for productive purposes. Since activated carbon is usually produced from waste carbon material, the scheme will potentially also aid solid waste management. Nigeria's under-utilized water bodies in the Niger Delta may provide for cheap transportation of activated carbon blocks to and from adsorption stations.
Saturation History Match Update of Ofon Field Reservoir Model Using Dynamic Parameters
Authors: Faseemo Oladipo 
Published: July 2013

Abstract
This paper highlights the basic steps taken to improve the history match of GOR and Water Cut in order to make the Ofon reservoir model more reliable for the forecasts necessary to optimise the revised scope of the OFON phase-2 project. The simulation study results were used to validate an optimal project case which involved drilling of 24 new wells, increased water injection capacity and implementation of gas lift injection in both existing and new wells.
Since saturation matching is mainly a mass transport (fluid flow) problem, it was decided to concentrate on dynamic parameters with known uncertainties. Based on the results of an uncertainty study performed with the in-house EST software, it was possible to determine which dynamic parameters had the most impact on water production and GOR within the limits of their uncertainties. It showed that relative permeability and critical gas saturation were the most influencing on water cut and GOR respectively. Sensitivities around experimentally acceptable limits of these parameters were undertaken leading to obtaining a best-case history matched model.
As the model was very pessimistic in water cut calculation (over-estimating observed water production), the relative permeability curves were thus adjusted by imposing Krw-Sw of the rock type with least water mobility on all the remaining 4 rock types in the model, while respecting the existing Kro-Sw functions of all rock types. This significantly improved field BSW although it was still necessary to perform local modifications around some individual wells to fine tune their water cut matches.
GOR matching was improved by sensitizing on the critical gas saturation uncertainty limits as determined from core experiments, leading to an improved field GOR match.
A test of the history matched model with recent production history confirmed its reliability for use as a predictive tool in the optimisation study for the Ofon phase-2 project.
Update of the GOR and BSW match improved the economics of the phase-2 project leading to the validation of a more cost-effective project scope.
Application of Empirically Derived Oil Recovery Factor Regression Equations to Water Drive Reservoirs in Niger Delta
Authors: Okpere Adrian , Charles Ndibueze 
Published: July 2013

Abstract
In order to make sound investment decisions with regards to oil field appraisal and development, it is crucial to be able to properly predict reservoir performance and hence oil recovery factor. Oil recovery factor is the recoverable fraction of the initial oil in place. It varies across different reservoirs depending on depositional environment, drive mechanism, rock and fluid properties.
Over the years, a variety of methods have been used for the estimation of oil recovery factors vis (Analytical, Simulation, Empirical e.t.c). The thrust of this paper will focus on the use of empirically derived recovery factor regression equation for estimating oil recovery factor for water drive reservoirs in the Niger Delta. This method was first developed by the American Institute of Petroleum (API) subcommittee on recovery efficiency in Nov., 1967 with the publication of API Bulletin D14 "A Statistical Analysis of Recovery Efficiency" The subcommittee used case histories from some 312 producing oil reservoirs with sandstone lithology from which certain empirical relationships were derived by regression analysis. Specific regression equations were developed for Water-drive and Solution gas reservoirs.
This paper presents the practicality of using the regression equation for water drive reservoirs in the Niger Delta, which have similar lithology. Firstly, a form of robustness check was done with mature reservoirs to see how well prediction from the regression equations line up with reality. Secondly, the equation was used to predict recovery efficiency in green reservoirs and results compared with other recovery factor estimation methodology noting the standard deviation in both cases. The results compared favorably and could be used as an additional robustness check when estimating reservoir recovery factor for water drive reservoirs in the Niger Delta.
Insights from the 3D Modeling of a Densely Faulted, Stacked Reservoir System
Authors: Oluseyi Ekanem , Osemoahu Omobude , Uchenna Onyemannadi , Ugochukwu Aboaja 
Published: July 2013

Abstract
The field presented in this paper is a structurally complex onshore oil field in the Niger Delta, with a densely faulted succession of stacked reservoirs. From previous field studies, three of the reservoir units have been interpreted as a single stacked reservoir complex beneath a top seal, and the vertical and lateral communication between these units is largely controlled by the inter-reservoir shales and intense fault configuration.
Integrated 3D reservoir modeling has been used to investigate the production performance from this stacked reservoir complex, with a view to identifying the features that contribute to the observed communication across the reservoirs, quantifying the contribution of each reservoir unit to each well's production, estimating the ultimate recovery for the complex and evaluating the current redevelopment plan for the reservoir complex to identify opportunities for further oil development.
The results from the study indicate that oil recovery is majorly influenced by communication across faults. A tracer model was used to demonstrate that some wells produce from adjacent blocks on the same reservoir unit as well as the other reservoir units across the fault, giving an indication of the presence of non-sealing faults across juxtaposed oil-bearing sands. Also the application of the 3D model in evaluating the current redevelopment plan for the reservoir complex resulted in the identification of 5 new opportunities in existing wells, to increase the ultimate recovery of the reservoir complex by 7.8MMstb. More so, there exists an opportunity to recover 7.5MMstb from a by-passed section of the complex with a new vertical well.
Reconstruction and Re-Interpretation of Pressure Transient Data from Old Well Tests Using Digitization Technique
Authors: Ikwan Ukauku , Peter Ikenebomeh , Dike Nnamdi , Chima Emelle 
Published: July 2013

Abstract
Pressure transient analysis is a veritable technique for reservoir characterisation offering a variety of oil and gas field development information ranging from reservoir permeability, anisotropy, boundaries to wellbore skin, well interference and productivity/injectivity to mention but a few. Well test data acquired at exploration and appraisal stages of oil and gas fields and their interpretation often times need to be re-visited at field development stage when this information are needed to underpin field development plan and reserves assessment. Changing perspective in field understanding as well as advances in well test interpretation may warrant a re-interpretation of pressure transient data from old well tests but at this stage Petroleum Engineers are faced with challenge of unavailability of test data in electronic form to re-visit interpretation with new techniques. Often times data may only exist in paper form.
In the quest to grow Africa Oil and Gas production, this paper is sharing a successful investigation of a technique for digitising pressure transient data that exist in paper form into electronic data for the purpose of reinterpreting an old test with recent advances in interpretation technique. The approach is illustrated with results from field testing of a multi-rate test data of a gas well in the Niger Delta acquired and interpreted in the early ‘90s but undergoing field development planning and resource volume evaluation two decades later.
Good results were obtained in the field trial, using the techqnique offered in this paper. The re-interpreted reconstructed pressure transient data led to permeability improvement from about 30 to 80 mD using appropriate models in consonance with advances in well test interpretation. This result has been used to update the simulation models for field development planning and reserves booking purposes for the trial field.
CFD Investigation of Application Potentials of Molybdenum Trioxide as Drilling Fluid Additive for HPHT Drilling Applications
Authors: Mohammed Auwalu Inuwa , Oluyemi Gbenga , Ibrahim Sulaiman Dodo 
Published: July 2013

Abstract
Rheology of drilling fluids is usually evaluated without taking wellbore pressure and temperature effects into consideration. In most instances these evaluations produce fairly accurate results for shallow wells owing to the usually very small difference between surface and subsurface bottom-hole temperatures in shallow wells. As such, the rheology of the drilling fluid does not change substantially while drilling wells of these types. However, in wellbores where bottom-hole pressures and temperatures are well above the average pressure and temperature, especially in deep and ultra-deep wells, significant changes in drilling fluid rheology may result. A classic example of this scenario is common in HPHT drilling environments. In these difficult and challenging environments pore pressure gradient could be in excess of 0.8psi/ft and bottom hole temperature (BHT) in the range of 150°C to 300°C or even greater.
Invert emulsion drilling fluids have reportedly been used to drill HPHT wells with temperature of up to 260°C with little problems or challenges. Nevertheless, recent HPHT activities have presented more difficult challenges with bottom hole temperature approaching 316°C and pore pressure in the neighbourhood of 20000 psi. These challenges have in turn presented the need to adopt a further innovative approach to drilling fluid management under this extreme condition.
This paper presents a numerical investigation of application potentials of molybdenum oxide as a rheology control additive in drilling fluids for more challenging HPHT well drilling. Simulations were carried out using Ansys Fluent CFD™ software whilst analysis and interpretation of results was carried out with the aid of Tecplot Visualisation™ Software.
The Simulations replicated the real life flow scenarios for both concentric and eccentric annuli under bottom-hole conditions of HPHT; and rotating (dynamic) and non-rotating (static) drill pipes.
Application of Molybdenum as a drilling additive for all the simulated scenarios resulted in improved effective drilling mud viscosity, supporting the conceptual propposition that molybdenum oxide can serve as a good additive for drilling fluid rheology control and maintenance in HPHT environments.
Environmental Remediation of Oil Spillage in Niger Delta Region
Authors: David Olayinka E. , Joel Ogbonna F. 
Published: July 2013

Abstract
The impacts of oil spills are not limited to the direct effect on the ecosystem; it goes a long way to affect the social welfare, aggravates poverty, population displacement, social conflict, production reduction and also affects the profit margin of the companies involved. This study is aimed at providing a review and comparison of the remediation techniques currently in use and suggest the most suitable methods of oil spill cleanup and remediation in Nigeria Niger Delta region based on certain criteria and to also suggest ways of mitigating oil spill occurrences in this region. In the course of this research study, data collection was on primary and secondary data. For the primary data, a structured questionnaire was drafted and used for survey relating to the research study to rank and evaluate different perspectives of stakeholders on various remediation techniques that are in consideration. For the Secondary Data, the study was carried out with a literature study to gain an overview of the different remediation methods for PHCs contaminated soils.
Finally using specific criteria including cost efficiency, operation and maintenance of the technique, environmental friendliness, time frame of achieving remedial objectives, health concerns, and applicability of the techniques were used to make an evaluation design for the different remediation techniques for hydrocarbons contaminated soils.
The results from these studies show that single remedial action cannot be used for cleanup but the Thermal desorption and Remediation by Enhanced Natural Attenuation (RENA) was the best placed technique ranking highest under the different criteria of the evaluation design and the sample survey of the remediation techniques considered. More so, In-situ Vitrification is the most cost effective techniques with little or no disturbance of site.
Global Trend in Natural Gas Development and the Impact on the Nigerian Gas Market
Authors: Aimikhe V. J , Kinigoma B. S , Iyagba E. T 
Published: July 2013

Abstract
This paper takes a proper look at the current trend in Global gas development worldwide and the impact on the Nigerian Gas market. With the global gas demand set to rise above 50% between 2010 and 2035, reaching 25% of the world's energy mix, overtaking coal to become the second largest primary energy source after oil, it becomes highly imperative for gas producers to fully understand the dynamics of this growth trend. The boom in unconventional gas development in some countries of the world especially the United States who is currently a major destination of the Nigerian gas, is expected to become a net exporter by the year 2016, resulting in revenue loss from gas sales in Nigeria. The increased expansion of LNG facilities and hence production capacity in major gas producers like Australia and Qatar while growth in Nigeria has remained stagnant will affect the country's revenue from gas in the nearest future. Also, the new discoveries of large gas reserves in some countries in East Africa including Mozambique and Tanzania located in the Indian Ocean will reduce operating cost of LNG buyers in Asia when these two Nations's LNG projects come on stream in 2018, as compared to buying from Nigeria.
This paper therefore takes a look at how these trends affect the Nigerian gas Market and suggests possible ways of avoiding revenue loss from gas sales in the nearest future.
Sidetrack/Recompletion Time Evaluation by Proxy Model
Authors: Ajibola J. T. , Orodu O. D. , Onyeukwu C. A. 
Published: July 2013

Abstract
Sidetrack during field development and ongoing production arises to exploit bypassed reserves (unswept areas under secondary and/or tertiary recovery), unexploited zones and unforeseen conditions likely to build due to uncertainties and heterogeneity in initially characterizing a reservoir. Whereas recompletion is prone due to sequential production of stacked reservoirs or multiple pay zones that is necessitated by regulation on comingling. The purpose of this paper is to optimize the time for sidetrack/recompletion job in multiple pay zones in view of maximizing returns on investment. A simple case to elicit the workflow is based on two pay zones and applies Experimental Design (ED), and economic analysis in the form of Net Present Value (NPV).
The procedure followed for this study started with the identification of the reservoir uncertainties and their ranges; focusing basically on net pay thickness, porosity, permeability, and time to perform the sidetrack; the reservoirs are assumed to be undersaturated. The Box-Behnken response surface design in ED was used to reduce the number runs to make by generating the most effective combination of variables for the experiment. Experimental runs were conducted with a Black Oil reservoir simulator to give production profile. NPV values using stipulated Oil price, CAPEX, OPEX, tax rate, royalty and production rates were estimated, which was used afterwards to produce the Proxy model in ED and this developed correlation was used to analyse the effect of time changes. NPV computed from the Proxy Model was reasonable; however, a higher level D-Optimal design as against the 2-level design used in this study may be required for a reasonable match of NPV with respect to sidetrack (recompletion) time.
In conclusion, the incorporation of time was successful and gives way to studying the impact of not only reservoir uncertainties but the uncertainty that arises from a success or failure of the sidetrack that further gives way to the application of decision analysis and the evaluation of NPV by Proxy Models for each possible outcome.
Milling on Electric Line-Conveyed Technology in West Africa
Authors: Dulie Almir 
Published: July 2013

Abstract
A new application of electric wireline (e-line) tractors in combination with well milling technology has been successfully proven in two wells in West Africa.
In July of 2011 on an offshore platform, a downhole tractor in conjunction with a milling tool were conveyed on e-line to remove an obstruction created by Lost in Hole (LIH) electric wireline cable at 9,500ft (2,896m).
In total, 13 successful milling runs were made. During this unique operation most of the milled wireline material was recovered, and the challenges of controlling rate and milling penetration were overcome. In between milling runs, slickline fishing attempts were made to recover the remaining LIH wireline. After the last milling run, a major breakthrough was made as fishing operations were successful in retrieving sufficient wireline to reach the target depth.
In another case, this time in a subsea well, a flapper valve used to set a production packer needed to be opened, but despite multiple pressure cycles down the tubing, the valve remained closed. The operator had the option to pump in acid to disintegrate the valve, but due to the estimated volume of acid required, the operator wanted a different solution.
The milling tool was fitted with a tungsten carbide milling bit specially designed to mill the aluminum flapper valve. The milling bit was designed with a spring-loaded skirt that kept the valve closed while the bit was exposed. This prevented the flapper valve from opening when pulling the bit backwards. After approximately 20 minutes of milling time, the valve was milled out. The operator saved at least one day of operation.
Additionally, due to their lightweight nature, e-line tools offer HSE benefits and logistical advantages. This paper describes the process from decision-making to completion of these milling operations.
Method of the Moulding Sands Binding Power Assessment in Two-Layer Moulds Systems / Metoda oceny wielkości siły wiązania mas w układzie form dwuwarstwowych
Authors: Holtzer M. , Drożyński D. , Bobrowski A. , Makselon J. 
Published: July 2013

Abstract
More and more foundry plants applying moulding sands with water-glass or its substitutes for obtaining the high-quality casting surface at the smallest costs, consider the possibility of implementing two-layer moulds, in which e.g. the facing sand is a sand with an organic binder (no-bake type) and the backing sand is a sand with inorganic binder. Both kinds of sands must have the same chemical reaction. The most often applied system is the moulding sand on the water-glass or geopolymer bases - as the backing sand and the moulding sand from the group of self-hardening sands with a resol resin - as the facing sand. Investigations were performed for the system: moulding sand with inorganic GEOPOL binder or moulding sand with water glass (as a backing sand) and moulding sand, no-bake type, with a resol resin originated from various producers: Rezolit AM, Estrofen, Avenol NB 700 (as a facing sand). The LUZ apparatus, produced by Multiserw Morek, was adapted for investigations. A special partition with cuts was mounted in the attachment for making test specimens for measuring the tensile strength. This partition allowed a simultaneous compaction of two kinds of moulding sands. After 24 hours of hardening the highest values were obtained for the system: Geopol binder - Avenol resin.