bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modifying the Performance Index in evaluating Risky Oil and Gas Investments
Authors: Akinpelu L. O. , Isehunwa S. O. 
Published: July 2016

Abstract
Oil and Gas investments are inherently risky, especially in upstream exploration where technical risk is predominant. Because of the large upfront expenditure required for these projects, it is imperative that investors in the business are well informed of the risk to which their capital is exposed. However, most commonly used performance measures focus on one aspect of what is a multidimensional problem. While expected value gives an indication of the amount of value created by the investment, the standard deviation gives an insight into the distribution of expected returns. The Performance Index combines these two insights into a single measure, value created per unit of variability (the standard deviation), which is a significant improvement over the one dimensional measures.
However, the Performance Index, PI is based on total variance and does not reflect the uncertainty structure of the risky investment. PI does not distinguish between upside and downside variances and can sometimes give a lower ranking to a prospect with large upside variance (High gain situation) leading to the Paradox of aversion to incremental reward (PAIR). We show this flaw in PI in an expected value maximization context as well as in an expected utility maximization context.
Semi-variance analysis gives an insight into the uncertainty structure of a risky investment. We use semi-variance analysis to propose a modification to PI to eliminate the problem of PAIR. Total variance is decomposed into upside and downside variances and the modified PI estimated based on downside variance alone. In decomposing the variance, we recommend using a threshold value to avoid the problem of a "shifting mean". We demonstrate through two examples (1) that though conventional PI may correctly rank risky prospects, non-recognition of the uncertainty structure does not accurately reflect the risk characteristics of an investment, and through a second example, a well drilling situation in which conventional and the modified PI lead to different ranking and investment decision recommendations.
Effects of Mud Filtrate Invasion on Well Log Measurements
Authors: Akinsete Oluwatoyin O. , Adekoya Doyinsola A. 
Published: July 2016

Abstract
Invasion of mud filtrate into surrounding formation affects most data acquired by logging tools, which impedes accurate formation evaluation. The invasion process may result in formation damage and reduction in well producibility. The objectives of this work are to determine the effects of invasion on induction well logs, identify the invasion profile present, and to determine the factors influencing invasion. Therefore, a realistic model depicting the actual wellbore conditions is required in order to accurately analyze the invasion process, and its effects on well logs.
In this work, a numerical model is developed. The physics of mud filtrate invasion in overbalanced drilling is numerically simulated using a 3D multiphase fluid flow simulator. Sensitivity analysis is done to quantify the influence of several petrophysical parameters on the spatial distribution of mud filtrate away from the wellbore, and the corresponding effects on induction logging tools.
Result showed that the distribution of salt concentration due to the invasion of fresh water-base mud into a formation containing highly saline formation water affects resistivity measurements. Based on the plot of resistivity against radial distance of invasion from the wellbore, annulus invasion profile is found to be present. Also, sensitivity analysis showed that formation parameters such as porosity and permeability, in-situ fluid saturation and mudcake permeability are important factors to consider when determining the extent of filtrate invasion. A plot of formation resistivity versus formation porosity shows that a reduction of formation porosity from 0.25 to 0.1 increased the radial distance of invasion by about 70ft, and also shifted the annulus deeper into the formation.
Result also showed that both medium and deep induction logs can be affected by invasion, and this depends on the total time of invasion, the formation rock and fluid properties and mudcake properties.
Effects of Temperature and Pressure on Shale Cuttings Dispersion in Water Based Mud WBM Using NACL, CACL2, KCL Salts as Primary Inhibiting Agents and Polymer XCD Xanthan Gum as Secondary Inhibiting Agent
Authors: Babajide Ale , Adebowale Oladepo , Adesina Fadairo , Churchill Ako , Ifechukwu Micheals 
Published: July 2016

Abstract
The primary cause of wellbore instability is the interaction of water based mud with shales which usually involves the movement of water and ions into or out of shale thereby causing alterations in mechanical property of the shale resulting in dispersion of shale particles into the mud.
This work involves experiments to analyze the effects of chemical osmosis, diffusive flow prior to shale hydration and inhibition, determination of the effects of salt addition on pH and density of mud and also determination of the effect of Temperature and pressure other than just temperature on dispersion of shale cuttings into water based mud. It also shows the behaviour of shale in various inhibitive agents e.g NaCl, KCl, CaCl2 and Polymer XCD when being hot rolled.
Results from experiment performed in this work confirmed that osmosis and ionic diffusion play a great role in shale hydration and dispersion. It also showed that subjecting the system to temperature and pressure conditions other than just temperature caused more dispersion of shale into mud.
KCl was the best inhibitive agent as more shale cuttings were recovered from the mud while the least shale recovery was from CaCl2/salt formulation. A further experiment was performed by adding polymer XCD to the Salt/mud formulations so as to investigate its inhibitive capability; result showed that more shale cuttings were recovered as compared to when only Salt/mud was used.
Production Optimization in the Duke Field Using the IPM Suite
Authors: Alaigba David , Orodu Oyinkepreye D. , Aguilera Maria 
Published: July 2016

Abstract
This project focuses on building a reservoir sub-sea network model for a condensate field in the gulf of Guinea, the Duke Field. It integrates the five developed Duke reservoirs, development wells and subsea network using the Petroleum Experts' Integrated Production Model suite of software, (IPM) which is widely used in the E&P industry especially for integrated forecasting, surveillance and production system optimization that require integration of surface and subsurface models.
Following the acquisition and quality control of data from other teams working on the Duke Field, a network model which integrates the five Duke reservoirs, their associated wells and subsea network up to the production separator was built. The model was initialized and used to predict full field performance under different scenarios.
Finally, a water injection allocation sensitivity study was performed and the results were analyzed both technically and economically. From the technical point of view, the option to reallocate 10 kbwpd from reservoir U to reservoir P-upper North and another 10 kbwpd from Reservoir ST to reservoir Q-Lower brought about the optimum recovery. This was also supported by a simple economic analysis. It was then recommended that additional water injectors be drilled in P-Upper North and Q-Lower to unlock an additional 8.4 MMSTB of reserves resulting from higher sweep efficiencies and better pressure maintenance.
Evaluating the Effect of Temperature and Polymer Concentration on Properties of Xanthan Gravel Pack Fluid
Authors: John A. O. , Joel O. F. , Chukwuma F. O. 
Published: July 2016

Abstract
Sand production from oil wells is undesirable and could have several consequences. There are several techniques of controlling or minimizing sand production from wells. Gravel Packing is one the most reliable methods of sand control. The success of gravel pack job operations in the field depends, to a large extent, on the fluid designs. Several types of polymers have been used in the past and some are still currently being utilized as gelling agents for gravel pack fluids. Different polymers impart different properties on the fluid system, making the fluid to exhibits different behaviours at different downhole conditions and this can have positive or even negative effect on the job execution. The polymer used for preparing gravel carrier fluids must have acceptable properties to match the well and engineering design requirements to prevent job failure and/or formation damage. Xanthan polymer has shown excellent gravel carrying capacity and good gel strength. In this study, the effect of temperature and polymer concentration on the degradation of xanthan was evaluated with different concentration of Sodium Persulfate oxidizer breaker. The proppant carrying capacity at different temperatures was also investigated. Test results indicated that gel break time, rheology and sand suspension properties are function of temperature, breaker and polymer concentrations.
Challenges and Prospects of the Use of Horizontal Directional Drilling Techniques for Laying Oil and Gas Pipelines in Nigeria
Authors: Ibeh S.U. U , Nnakaihe S.E. E 
Published: July 2016

Abstract
Nigeria pipelines especially the petroleum and petroleum product pipelines are always vandalized by the sabotage. Huge amount of money is expended to put the damaged pipeline in good shape, and petroleum and petroleum product transfer is sometimes hampered due to leakages and damages caused by the oil thieves. Also huge money is being budgeted yearly to secure the pipelines. To combat this problem, Horizontal Directional Drilling (HDD) is being proposed.
HDD is a method of installing underground pipes and conduits along a prescribed bore path from the surface, with minimal impact to the surrounding area. Installation lengths up to 6500ft and depth of 200ft have been completed and diameters up to 48 in. have been installed in shorter runs. The process begins when a directional bore machine pushes a bore head connected to hollow pipe into the ground at an angle. As each joint of drill pipe is pushed into the ground a new one is added behind. In rock, a mud motor, which converts the hydraulic pressure of the drilling fluid into mechanical rotation, is used to rotate the bit and the drill pipe is not continuously rotated. Steerage is accomplished by aligning the angle of the mud motor to the desired direction.
This paper investigates the challenges and prospects of using the HDD technique to lay pipeline to a greater depth/distance that will be inaccessible by the oil thieves. The construction process (pilot hole, reaming and pullback) along with the major components (drill rig, drill pipe, slurry, slurry recycling, survey equipment, drill bits, and reamers) is discussed. The advantages of cost reduction, and environmental, social and time benefits were examined in this study. The challenges of proper soils information, subsurface conditions, training and knowledge, drilling fluids and binding of the drill pipe and reamer/bit are highlighted.
Improved Reservoir Fluid Modeling Using Optimized Flash Calculations
Authors: Ogali Oscar I. , Egbe Samuel O. 
Published: July 2016

Abstract
A realistic reservoir fluid model is important when studying the mechanics and dynamics of a reservoir. One of the methods used in building reliable fluid models is the equation of state. Fluid description using this method is iterative and largely depends on the speed and accuracy of the flash calculations used to generate the equilibrium ratios. In this study, a machine learning technique known as the gradient descent algorithm, was used to optimize the fluid modeling process in terms of time, computer resources and accuracy. This involved applying the gradient descent algorithm to the flash calculations. Fluid models built using equations of state are often uncertain for practical use. This is due to errors in the predictions of the model. Thus, experimental data was used to tune the thermodynamic parameters of the developed fluid model, using automatic non-linear regression, so as to further improve the accuracy of the model. The results show a physically and mathematically acceptable fluid model with accuracies up to 5 decimal places. Therefore, optimizing fluid modeling processes using machine learning techniques can improve the overall speed and accuracy of the process.
Application of Artificial Intelligence Techniques in Drilling System Design and Operations: A State of the Art Review and Future Research Pathways
Authors: Bello Opeyemi , Teodoriu Catalin , Yaqoob Tanveer , Oppelt Joachim , Holzmann Javier , Obiwanne Alisigwe 
Published: July 2016

Abstract
Artificial Intelligence (AI) has found extensive usage in simplifying complex decision-making procedures in practically every competitive market field, and oil and gas upstream industry is no exception to it. AI involves the use of sophisticated networking tools and algorithms in solving multifaceted problems in a way that imitates human intellect, with the aim of enabling computers and machines to execute tasks that could earlier be carried out only through demanding human brainstorming. Unlike other simpler computational automations, AI enables the designed tools to "learn" through repeated operation, thereby continuously refining the computing capabilities as more data is fed into the system.
Over the years, AI has led to significant designing and computation optimizations in the global Petroleum Exploration and Production (E&P) industry, and its applications have only continued to grow with the advent of modern drilling and production technologies. Tools such as Artificial Neural Networks (ANN), Generic Algorithms, Support Vector Machines and Fuzzy Logic have a historic connection with the E & P industry for more than 16 years now, with the first application dated in 1989 for development of an intelligent reservoir simulator interface, and for well-log interpretation and drill bit diagnosis through neural networks. Devices and softwares with basis from the above mentioned AI tools have been proposed to abridge the technology gaps hindering automated execution and monitoring of key reservoir simulation, drilling and completion procedures including seismic pattern recognition, reservoir characterisation and history matching, permeability and porosity prediction, PVT analysis, drill bits diagnosis, overtime well pressure-drop estimation, well production optimization, well performance projection, well / field portfolio management and quick, logical decision making in critical and expensive drilling operations.
The paper reviews and analyzes this successful integration of AI techniques as the missing piece of the puzzle in many reservoir, drilling and production aspects. It provides an update on the level of AI involvement in service operations and the application trends in the industry. A summary of various research papers and reports associated with AI usage in the upstream industry as well as its limitations has been presented.
Sensitivity Analysis of a Single Mixed Refrigerant Liquefaction Process of Natural Gas
Authors: Una D. C. , Oduola M. K. , Odagme B. S. 
Published: July 2016

Abstract
The demand for greater efficiency and large capacity for liquefaction process is inevitable for optimization. This study presents the sensitivity analysis of the factors that affects liquefaction processes of natural gas. Some of these factors are the natural gas pressure, temperature and composition on the single mixed refrigerant liquefaction process was simulated using ASPEN HYSYS 8.6 software. The effects of these parameters on specific power, power consumption and refrigerant flow rate of the process were simulations and examined. At constant pressure, temperature decreased from 15 to 5°C resulted in a 15% decrease in specific power and an increase from 15 to 25 °C resulted to 40% increase. At constant temperature, a decrease in natural gas pressure from 60 to 30bar and increase in specific power from 0.387 to 0.452 kWh/kg-LNG was observed which amounts to a 16.80% increase and when increased from 60 to 90bar specific power decreases from 0.387 to 0.348kWh/kg-LNG about 10.08 % decrease. Thus, when natural gas is supplied at a given pressure and temperature, a decrease in supply pressure will increase power consumption and an increase in supply pressure will decrease power consumption. The useful exergy for the system was about 26% of the total energy (46.42MW) available, indicating that about 74% of energy supplied by the compressor ended up as losses in different components in the process liquefaction cycle. However, the largest loss occurred in LNG heat exchanger and cooler which were to 25 and 24% respectively. The simulation results showed that, natural gas supplied at 150MMScf, 60bar and 15°C gave rise to LNG production of about 0.95MTPA.
Economics and System Metrics Applications for Upstream Capital Investment Performance Evaluation: An Empirical Review and Guide
Authors: Paraclete Nnadili , Adenike Adejola , Iledare Wumi 
Published: July 2016

Abstract
The petroleum industry is one of the most influential players in the world economy. The need to understand and assess the value in the oil and gas sector has never been greater than it is today. Over the next two decades the sector will need to invest substantial amounts of capital to meet the growing demand for energy which will involve rising cost pressure and competitive forces. Large scale of capital investment is required for most petroleum projects hence, it is important that investment decisions are based on a thorough analysis of variables and uncertainties. An ability to assess the viability of investments and the real value of oil and gas assets is critical to success where a range of complex technologies and facilities are required.
This paper examines the economics and system metrics application for upstream capital investment performance evaluation. Three capital investment choices (R, S, and T) were considered, using; the expected value analysis, decision tree analysis, stochastic dominance and @Risk tools.
Results show that stochastic dominance tests exposes the risk sensitivity of prospect R and S, opposing metrics results exposed the mutual exclusivity of the prospects and sensitivity analysis shows effect of uncertain dry hole probability on Expected Monetary Values (EMV). Therefore, for a strategic project selection, risk attitude of investor was introduced as a criterion for prospect selection between "R' and "S" and a range of dry hole probabilities (29% – 40%) was obtained for prospect "S".
Evaluating the Oil Mobilization Properties of Nanoparticles Treated with Arabic Gum and Xanthan Gum for Trapped Oil in Porous Media
Authors: Joseph-Igbor Bridget , Orodu Oyinkepreye D. , Afolabi Richard O. 
Published: July 2016

Abstract
The flow of multiple fluid phases in porous media often results in trapped droplets of the non-wetting phase. Recent experimental and theoretical studies have suggested that nanoparticle aqueous dispersions may be effective at mobilizing trapped droplets of oil in porous media. Hypotheses to explain the observation include the nanoparticles' modification of solid wettability, changes in interfacial tension and interface rheology. The difficulty in observing droplet behavior on the pore scale has made the understanding of such mechanism still unclear. In this work, the relationship between nanoparticle concentration and microscopic diversion of flow was investigated and how this impacts on the oil mobilization efficiency. Also investigated in this work was how the rheology of the dispersion medium for nanoparticles impacts on the overall recovery of trapped oil in porous media. A core flooding experiment was carried out on which aqueous solutions of different concentrations of the nanoparticle dispersion was used as the displacing fluid likewise rheological modified solutions of the nanofluids. The output of this work showed that the nanoparticle concentration impacts on the recovery of trapped oil through the microscopic diversion of fluid flow in porous media and this phenomenon in conjunction with earlier mention hypothesis effectively showed how nanoparticles enhances the recovery of trapped oil in porous media.
Synergistic Effects of Dispersed Bonny Light Crude Oil on Selected Aquatic Organism
Authors: Nwaizuzu C. , Joel O. F. , Sikoki F. D. 
Published: July 2016

Abstract
Oil spill dispersants (OSD) are known to be effective tools needed to clean and disperse oil spills. One major concern in the use of dispersants is their toxicity. The toxicity of individual chemicals may be known and be of no concern, but when combined with other chemicals they can have unknown additive or synergistic effects. This study was therefore designed to investigate the toxicological effects of OSD Seacare and Bonny light crude oil on the African Catfish (Clarias gariepinus). The 96hr acute toxicity of the water accommodated fraction (WAF) of the mixture of OSD Seacare and Bonny light crude oil was investigated as well as the critical body residue on the fingerlings of the African Catfish. The mean (±SD) weight and height of the fish was 1.27±0.37g and 5.35±0.57cm respectively. The following concentrations, 30, 90, 180 and 270ml/L, were used for the definitive test of the CEWAF. The LC50 for the CEWAF was determined to be 199.289ml/L while no death was recorded in the WAF-co. The oil spill dispersant Seacare synergized the toxicity of the crude oil on the test organism by more than 4.516 times further proving that oil spill dispersants can and do synergize the toxicity of crude oil on aquatic organisms. There was no PAH recorded in the fish from the control. From the fish exposed to 30ml/L of the dispersed oil concentration, the total PAH concentration was 0.730227ppm with 1 Benzo (g,h,i) perylene accounting for the total amount. Whereas the total PAH in the fish exposed to the 270ml/L concentration was 2.52903ppm with Naphthalene accounting for the total amount. After the acute toxicity testing and the test organisms were put in clean water, it was noticed that the test organisms exposed to the dispersed oil had a change in colour and there was reduced feeding in both those exposed to the WAF of the crude oil and dispersed oil.