bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characteristics of Dimensionless Pressure Gradients and Derivatives of Horizontal and Vertical Wells Completed within Inclined Sealing Faults
Authors: Ogbamikhumi A V , Adewole E S 
Published: August 2021

Abstract
Dimensionless pressure gradients and dimensionless pressure derivatives characteristics are studied for horizontal and vertical wells completed within a pair of no-flow boundaries inclined at a general angle ‘θ’. Infinite-acting flow solution of each well is utilized. Image distances as a result of the inclinations are considered. The superposition principle is further utilized to calculate total pressure drop due to flow from both object and image wells. Characteristic dimensionless flow pressure gradients and pressure derivatives for the wells are finally determined.
The number of images formed due to the inclination and dimensionless well design affect the dimensionless pressure gradients and their derivatives. For n images, shortly after very early time for each inclination, dimensionless pressure gradients of 1.151(N+1)/LD for the horizontal well and 1.151(N+1) for vertical well are observed. Dimensionless pressure derivative of (N+1)/2LD are observed for central and off-centered horizontal well locations, and (N+1)/2 for vertical well are observed.
Central well locations do not affect horizontal well productivity for all the inclinations. The magnitudes of dimensionless pressure drop and dimensionless pressure derivatives are maximum at the farthest image distances, and are unaffected by well stand-off for the horizontal well.
Alternative Energy Values in Natural Gasfractionation
Authors: Udie Celestine A. , Anuka Agnes A. , Ana Ekpenyong A. 
Published: August 2021

Abstract:
Global energy crisis has been on the increase due to increase on energy demand driven by population growth. In attempting to address the global energy crisis, this work uses the alternative resources to diversify the conventional energy sources in order to supplement the available energy generating sources. Energy resources are being evaluated to supplement the conventional energy sources thereby boosting the total energy generation in a nation. Technical and economic models are developed and used to evaluate the energy values in natural gas fractionation. Natural gas fractions evaluated include liquefied natural gas (LNG), liquefied petroleum gas (LPG) and condensate (liquid fuel). Collated field data are inputted into the developed economic models to estimate feasible technical and economic values in each of the gas fractions. The technical and economic analysis revealed that bulk natural gas contains 85.76% liquefied natural gas, 11.61% liquefied petroleum gas and 2.28% condensate (liquid). The result also revealed that natural gas fractionation improves its economic and energy values. With this, it is clear that the improvement in natural gas energy sources has the potency to supplement, hydro-electric power source, coal power source, oil and/or diesel fuel power sources.
Laboratory-Scale Investigation of the Utilisation of Multiple Flat-Fan Nozzles in Descaling Petroleum Production Tubing
Authors: Yar'Adua Kabir Hasan , John Idoko Job , Abbas Abubakar Jibril , Suleiman Salihu M. , Ahmadu Abdullahi A. , Kabir Aisha 
Published: August 2021

Abstract
Despite the recent wide embrace of mechanical descaling approaches for cleaning scales in petroleum production tubings and similar conduits with the use of high-pressure (HP) water jets, the process is still associated with downhole backpressure and well integrity challenges. While the introduction of sterling beads to replace sand particles in the water recorded high successes in maintaining well completion integrity after scale removal in some recent applications of this technique, it is, unfortunately, still not without questions of environmental degradation. Furthermore, the single nozzle, solids-free, aerated jetting descaling technique – recently published widely – is categorized with low scale surface area of contact, low descaling efficiency and subsequent high descaling rig time. The modifications to mechanical descaling techniques proposed in this work involve the use of three high-pressure flat fan nozzles of varying nozzles arrangements, standoff distances and injection pressures to remove soft scale deposits in oil and gas production tubings and similar circular conduits. This experiment provides further insights into the removal of paraffin scales of various shapes at different descaling conditions of injection pressures, stand-off distances and nozzle arrangements with the use of freshwater. The results obtained from this study also show consistency with findings from earlier works on the same subject.
A Suitable Model for Assessing the Integrity of Subsea Control Modules SCMs for Re-Use after Decommissioning
Authors: Root Eric , Andrawus Jesse , Iyalla Ibiye 
Published: August 2021

Abstract
This paper proposes a model for assessing Subsea Control Module (SCM) integrity for re-use after decommissioning. The SCM is one of the most failure-prone components in subsea oil and gas developments, and although a relatively inexpensive component in a Subsea Production System (SPS), the failure of an SCM can require production to be ceased, significantly impacting project economics. The re-use of decommissioned SCMs could improve the economics of subsea oil and gas projects by reducing design and manufacturing lead times, improving production availability, and enabling the economic exploitation of both marginal and mature fields. Insights gained through relevant literature, industry standards, and subsea industry experts led to the development of the Integrity Assessment Model for Decommissioned Subsea Control Modules proposed in this paper. The model is based on an Integrity Assessment process as well as a Risk-Based Compatibility Assessment. Discussions include a background of the SCM and common failures, the economics of SCM re-use, and Applications for the re-use of SCMs. The Integrity Assessment Model is described in detail, as well as the benefits and limitations. Areas of future research in support of subsea equipment re-use are identified, including improvements to reliability databases for subsea equipment, and the creation of a quantitative metric describing subsea equipment integrity.
Optimisation of Offshore Structures Decommissioning – Cost Considerations
Authors: Eke Emmanuel , Iyalla Ibiye , Andrawus Jesse , Prabhu Radhakrishna 
Published: August 2021

Abstract
The petroleum industry is currently being faced with a growing number of ageing offshore platforms that are no longer in use and require to be decommissioned. Offshore decommissioning is a complex venture, and such projects are expected to cost the industry billions of dollars in the next two decades. Early knowledge of decommissioning cost is important to platform owners who bear the asset retirement obligation. However, obtaining the cost estimate for decommissioning an offshore platform is a challenging task that requires extensive structural and economic studies. This is further complicated by the existence of several decommissioning options such as complete and partial removal. In this paper, project costs for decommissioning 23 offshore platforms under three different scenarios are estimated using information from a publicly available source which only specified the costs of completely removing the platforms. A novel mathematical model for predicting the decommissioning cost for a platform based on its features is developed. The development included curve-fitting with the aid of generalised reduced gradient tool in Excel® Solver and a training dataset. The developed model predicted, with a very high degree of accuracy, platform decommissioning costs for four (4) different options under the Pacific Outer Continental Shelf conditions. Model performance was evaluated by calculating the Mean Absolute Percentage Error of predictions using a test dataset. This yielded a value of about 6%, implying a 94% chance of correctly predicting decommissioning cost.
Challenges of Developing Marginal Fields in the Current Climate of Oil and Gas Industry
Authors: Danmadami Amina , Iyalla Ibiye , Oluyemi Gbenga , Andrawus Jesse 
Published: August 2021

Abstract
Marginal field development has gained relevance in oil producing countries because of the huge potential economic benefits it offers. The Federal Government of Nigeria commenced a Marginal Fields program in 2001 as part of her policy to improve the nation’s strategic oil and gas reserves and promote indigenous participation in the upstream sector. Twenty years after the award of marginal fields to indigenous companies to develop, 50% have developed and in production, 13% have made some progress with their acquisition while 37% remain undeveloped. The poor performance of the marginal field operators is due to certain challenges which have impeded their progress.
A review of challenges of developing marginal fields in the current industry climate was conducted on marginal fields in Nigeria to identify keys issues. These were identified as: funding, technical, and public policy. Considering the complex, competitive and dynamic environment in which these oil and gas companies operate, with competition from renewables, pressure to reduce carbon footprint, low oil price and investors expectation of a good return, companies must maintain tight financial plan, minimize emissions from their operations and focus on efficiency through innovation.
The study identifies the need for a decision-making approach that takes into consideration multi criteria such as cost, regulation, quality, technology, security, stakeholders, safety and environment, as important criteria based on which to evaluate the selection of appropriate development option for marginal fields.
Renewable and Unconventional Energies
Authors: Aniebo Igolo Nonye 
Published: August 2021

Abstract
Renewable and unconventional energies have finally moved from the realm of ideas to fact. They, as was expected and feared, have forced deep changes in world economies. Fortunately, they have, at the same time, begun to fulfill an aspect of the dream that made them an alluring idea in the first place- help humanity fight climate change. For decades, large scale exploitation of energy has been the preserve of industrialized nations. It is therefore understandable that they would lead the push for the practicalization of renewables and unconventional energies. Since the nations occupy less than a third of the world, their diminished carbon footprint will not be enough to reverse the effects of climate change. The objective of this research is to posit that just as these nations initiated and were mainly responsible for the excessive and unregulated use of fossil fuels all over the world, they should also try to do the same for renewables if they want to save humanity from the devastating effects of climate change. Nigeria, like most countries in Africa, is a case in point. Her fossil fuels, coal, oil, and gas were brought on stream in the twentieth century to satisfy foreign demands. Now that these demands have found other sources, a chaotic operation has been left for the locals to vandalize or operate, further creating a disastrous situation that will speed up climate change. What is true for Nigeria is equally true for more than 50 other foreign created/controlled countries of Africa, the second largest continent globally. Evaluation of research on renewable energy and Nigeria will be done to lay the facts bare and show the things that have to be put in place to start the process. The result will show that while there are constraints, Nigeria as a country will greatly benefit from policies based on renewables and unconventional energies.
The Contract Regime for Unitisation and the Impact of Production Sharing Contracts on Joint Development in Nigeria
Authors: James Mendos 
Published: August 2021

Abstract
Unitisation has evolved globally as the best mechanism for the joint development of hydrocarbon bearing reservoirs that straddle two or more concessions or licenses. The concept of unitisation is underpinned by the need to avoid competitive exploitation of hydrocarbon resources, maximise its economic recovery, eliminate proliferation of production facilities and reduce development and operating cost.1
The practice of unitisation in the Nigerian oil and gas landscape has gained traction over the years with several straddle fields identified as candidates for unitisation and more than ten (10) agreements for joint development (both Pre Unitisation Agreements and Unitisation and Unit Operating Agreements) executed in the industry. This has occurred under a regulatory regime for unitisation that has evolved from the concise provisions of Section 48 of the Petroleum (Drilling and Production) Regulation 1969 as amended, to the robust Guidelines for Unitisation issued by the Department of Petroleum Resources (DPR) in 2008 (revised in 2019) (Guidelines) in response to the complexities of joint development encountered by parties.
While the Guidelines is an excellent attempt at providing a process for unitisation, it does not provide sufficient guidance on the contract regime for unitisation as the bedrock for joint development. A critical look at the contracts governing joint development in the light of global best practices is important to ensure that it meets in an effective manner the objectives of unitisation. A review of the contract regime for unitisation would be incomplete without recognising the impact that underlying contracts governing separate concessions have on unitisation. To this end, the posture of Production Sharing Contracts (PSCs) on gas development in a unit is worth reviewing in the light of the benefits of commercialising gas to the State and the Contractor.
This paper reviews the contract regime for unitisation in Nigeria as regulated by the Guidelines and the impact that underlying contracts (particularly PSCs) have on unitisation. The paper will proffer recommendations for inclusion in the Guidelines with a view to improving the process of joint development of shared reservoirs in Nigeria.
Solid-Fluid Phase Equilibria Measurement for Mixtures of Methane, Carbon-Dioxide and N-Hexadecane
Authors: Eniolorunda Oluwakemi Victoria , Chapoy Antonin , Burgass Rod 
Published: August 2021

Abstract
In this study, new experimental data using a reliable approach are reported for solid-fluid phase equilibrium of ternary mixtures of Methane-Carbon-dioxide- n-Hexadecane for 30-73 mol% CO2 and pressures up to 24 MPa. The effect of varying CO2 composition on the overall phase transition of the systems were investigated. Three thermodynamic models were used to predict the liquid phase fugacity, this includes the Peng Robison equation of state (PR-EoS), Soave Redlich-Kwong equation of state (SRK-EoS) and the Cubic plus Association (CPA) equation of state with the classical mixing rule and a group contribution approach for calculating binary interaction parameters in all cases. To describe the wax (solid) phase, three activity coefficient models based on the solid solution theory were investigated: the predictive universal quasichemical activity coefficients (UNIQUAC), Universal quasi-chemical Functional Group activity coefficients (UNIFAC) and the predictive Wilson approach. The solid-fluid equilibria experimental data gathered in this experimental work including those from saturated and under-saturated conditions were used to check the reliability of the various phase equilibria thermodynamic models.
Application of Machine Learning Techniques in Reservoir Characterization
Authors: Okon Edet Ita , Appah Dulu 
Published: August 2021

Abstract
Application of artificial intelligence (AI) and machine learning (ML) is becoming a new addition to the traditional reservoir characterization, petrophysics and monitoring practice in oil and gas industry. Accurate reservoir characterization is the driver to optimize production performance throughout the life of a field. Developing physics-based data models are the key for applying ML techniques to solve complex reservoir problems. The main objective of this study is to apply machine learning techniques in reservoir Characterization. This was achieved via machine learning algorithm using permeability and porosity as the investigative variables. Permeability and porosity of a reservoir were predicted using machine learning technique with the aid of XLSTAT in Excel. The general performance and predictability of the technique as applied to permeability and porosity predictions were compared. From the results obtained, it was observed that the machine learning model used was able to predict about 98% of the permeability and 81% of the porosity. The results from Al and ML will reinforce reservoir engineers to carry out effective reservoir characterization with powerful algorithms based on machine learning techniques. Hence, it can therefore be inferred that machine learning approach has the ability to predict reservoir parameters.
Velocity Dependence and Tracer Dispersion in Newtonian Fluids Undergoing Creeping Flow
Authors: Ayuba Ibrahim , Akanji T. Lateef , Gomes J. L. 
Published: August 2021

Abstract
The dynamics of tracer particles in a viscous Newtonian fluid is studied analytically and numerically through channels of varying thickness for fluids undergoing creeping flow. Exact analytical solutions of mass conservation equations of tracer particles including consideration for pressure forces are obtained. Results of the analysis indicates that Stokes velocity is an indispensable parameter and is dependent on parameters such as channel thickness (height), viscosity of the fluid, pressure gradient driven the fluid and Reynolds number corresponding to the channel thickness. The accuracy of the solution obtained is verified by comparing its velocity profiles with those obtained from finite-element-based numerical simulation studies.
De-Risking Thermal Induced Sustained Annulus Pressure to Safeguard Optimal Production
Authors: Maxwell-Amgbaduba Sunday , Ogbonna David , Obakhena Femi , Okereke Onyedikachi , Green Ihuoma , Volkov Maxim , Oyanu Ruth 
Published: August 2021

Abstract
Sustained Annulus Pressure (SAP) is a common production constraint in the oil and gas industry, it is usually caused by impaired seal Integrity within the wellbore system resulting in barrier failures. In peculiar scenarios the thermal expansion creates pressure build-up in the annulus as well which can equally impair the integrity of the wellbore.
In this paper the results of downhole and surface pressure monitoring surveys are presented, the objectives aim at determination of both downhole leaks and verification the influence of thermal expansion into a wellbore system integrity in a field located onshore Niger Delta. SAP in a producing well was earlier recorded during routine annular pressure monitoring in 2017 during the production rate increase by changing the bean size from 18/64" to 24/64".
Initial diagnostics observed pointed towards SAP resulting from a possible downhole seal integrity issue leading to a leak to the surface. While putting the well on stream with current bean size and the pressure regime for both THP and CHP was observed. Pressure with time analysis showed annulus pressure builds up rapidly while flowing and bleeds off within 30 min from 700 psi to 0 psi when well shut in. Downhole logging and sensitive passive acoustic monitoring was conducted, the survey aimed to detect barrier failures by capturing its acoustic leak patterns under shut-in and bleeding off condition. Considering the suspected leak behaviour, the data acquisition included the procedure to build up the annulus pressure by flowing the well and monitoring the annulus discharge.
Integrity logs survey and passive acoustic monitoring confirmed there were no downhole failures and after several bleed-offs when Tubing choke was beaned down to 18/64" no annulus pressure build-up was observed from the Well head gauge on the Casing head confirming the source of the sustained annulus pressure is driven by the temperature expansion of the annulus fluid.
Remedial action and recommendation after Simulation were to de-risk the well at a controlled bean size to mitigate SAP and optimally flow the well.
Modeling and Predicting Performance of Autonomous Rotary Drilling System Using Machine Learning Techniques
Authors: Amadi Kingsley , Iyalla Ibiye , Prabhu Radhakrishna 
Published: August 2021

Abstract
This paper presents the development of predictive optimization models for autonomous rotary drilling systems where emphasis is placed on the shift from human (manual) operation as the driving force for drill rate performance to Quantitative Real-time Prediction (QRP) using machine learning. The methodology employed in this work uses real-time offset drilling data with machine learning models to accurately predict Rate of Penetration (ROP) and determine optimum operating parameters for improved drilling performance. Two optimization models (physics-based and energy conservation) were tested using Artificial Neutral Network (ANN) algorithm. Results of analysis using the model performance assessment criteria; correlation coefficient (R2) and Root Mean Square Error (RMSE), show that drill rate is non-linear in nature and the machine learning model (ANN) using energy conservation is most accurate for predicting ROP due to its ability in establishing a functional feature vector based on learning from past events.
Identification and Validation of Novel Endogenous Controls for qPCR Normalization in SK-BR-3 Breast Cancer Cell Line
Authors: Jain Nityanand , Mitre Ingrida , Nitisa Dina , Pirsko Valdis , Cakstina Inese 
Published: August 2021

Abstract
Normalization of gene expression using internal controls or reference genes (RGs) has been the method of choice for standardizing the technical variations in reverse transcription quantitative polymerase chain reactions (RT-qPCR). Conventionally, ACTB and GAPDH have been used as reference genes despite evidence from literature discouraging their use. Hence, in the present study we identified and investigated novel reference genes in SK-BR-3, an HER2-enriched breast cancer cell line. Transcriptomic data from 82 HER2-E breast cancer samples from TCGA database was analyzed to identify twelve novel genes with stable expression. Additionally, thirteen RGs from literature were analyzed. The expression variations of the candidate genes were studied over five successive passages (p) in two parallel cultures S1 and S2 and in acute and chronic hypoxia using various algorithms. Finally, the most stable RGs were selected and validated for normalization of the expression of three genes of interest (GOIs) in normoxia and hypoxia. Our results indicate that HSP90AB1, DAD1, PFN1 and PUM1 can be used in any combination of three (triplets) for optimizing intra- and inter-assay gene expression differences in the SK-BR-3 cell line. Additionally, we discourage use of conventional RGs (ACTB, GAPDH, RPL13A, RNA18S and RNA28S) as internal controls for RT-qPCR in SK-BR-3 cell line.