bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimizing Brown Fields Through Adherence to Proper Well Intervention Workflow
Authors: Chinweike Okeke 
Published: October 2018

Abstract
The sudden fall of crude oil prices starting from the end of year 2014 got many astonished, as the price of Brent crude fell from $110 per barrel to $27 per barrel early 2016. Oil and gas producing companies were coerced to reduce spending on risky and costly exploration and production projects. Without doubt, all attention will be focused on production optimization from brown fields through the use of different well intervention strategies as the only proved means to gain more by spending less. Oil price has improved, hovering around $70 to $81 per barrel, in this current period of low oil price, there is much reason to embrace different well intervention strategies to keep wells on-stream more commercially. Since brown fields account for over seventy percent of the world’s energy demands, there is the need to revitalize these brown fields. With advances in well intervention strategies, getting as much as possible from a brown field is becoming more and more feasible. Thus, this study aims to develop the best workflow to optimize production through the application of different well intervention strategies. The results from a mature field in the Niger Delta were used to analyze the improvement of production through different well interventions. Extensive analysis of production history/performance, review of petrophysical parameters, identification of some subsurface (down-hole completions/well deliverability) and surface (facilities) constraints were carried out. The field has eight reservoirs, twenty-three wells, thirty-eight strings out of which production optimization using well interventions were applied on seventeen of the strings. Eclipse dynamic simulation software, Prosper and Ecrin well-test software were used to build the necessary models and analyze different sensitivity scenarios before and after each well intervention.
Experimental Study of Effects of Water-in-Oil Emulsions Flow on Wax Deposition in Subsea Pipelines
Authors: Adeyanju Olusiji Ayoade , Oyekunle Layioye Ola 
Published: October 2018

Abstract
Experiments were performed to simulate the wax deposition in the flow of water in crude oil emulsions in subsea pipelines using a flow facility. Two water in crude-oil emulsions (Samples A & B) synthesize from two crude oil samples and their respective formation water from Orogbo and Okpohuru flow stations in the Southern Nigeria were used in the study. In the later period of wax deposition the combined effects of molecular diffusion and shear removal overwhelm the trapped water globules effect which dominates the wax deposition initially. The emulsions pour points increase from 30 to 41°C and the viscosities at 26 oC from 40 to 142 mPas, when the basic sediments and water of the crude samples increase from 10 to 40 °C. Addition of 250 ppm of Basorol E2032 (demulsifier) to the mixture of crude oil emulsion and 450ppm of long chain acrylate ester co-polymer (pour point depressant) was able to reduce the dimensionless wax thickness by 21.4 and 8.7% for crude oil samples A & B respectively. Addition of the demulsifier to the mixture of the emulsified oil and the pour point depressant enables the emulsified crude oil to be separated into its separate compositions of crude oil and water thereby making the stratified water-crude oil liquid flow to characterize the fluid flow in the pipeline leading to reduction in wax deposition.
The Effects of Hole Wash-Out on Wellbore Centralization and Effective Zonal Isolation in Consolidated and Unconsolidated Gas Reservoirs
Authors: Adesanya Olukayode , Mofunlewi Samuel S. , Ighodaro Osaze , Idongesit Victor , Dickson Tobin 
Published: October 2018

Abstract
Formation evaluation and geological characteristics of the reservoir have been key factors that help in determining the best practices in drilling and completion operations. Primary cementing in unconsolidated or consolidated gas formations presents even bigger challenges due to the volatility of gas and a high risk involved with respect to maintaining good well control across the various phases involved in delivering a well.
To achieve good zonal isolation through cement placement, it is important to ensure that best operational cementing practices are properly incorporated with a robust slurry design based on specific formation data. Beyond the reliability of these factors, it is important to have accurate hole data which inform the optimum centralizer program and volume determinations. One key factor that hinders the accuracy of this information is the extent of wash-outs in an open hole. Hole wash-outs and the level of wash-outs in a wellbore depends on various factors some of which includes, the degree of consolidation of the formation environment, the practices deployed during the drilling phase of the wellbore and the operationally-influenced delays due to challenges experienced in the drilling phase of the hole section.
Over time, the levels of wash-out experienced in a wellbore have been seen to greatly influence the centralization effectiveness, and depth accuracy with respect to annular slurry placement. This paper will be analyzing case studies from gas wells that were drilled in both consolidated and unconsolidated formations, the effect of wash outs on the centralization stand-off and how these wash-outs affect the quality of zonal isolation across these hole sections. The paper will include best practices to improve zonal isolation when dealing with wash-out intervals.
The Effect of Biochar on Residual Polyaromatic Hydrocarbon Concentrations in Bioremediation
Authors: Oriaku T. O. 
Published: October 2018

Abstract
In this study, the efficiency of biochar as a remediation tool in reducing the concentration of residual pollutant concentrations (polyaromatic hydrocarbons- PAHs) in coal tar remediated soils was investigated over a 30-day period. Results from laboratory microcosm experiments showed that amendment with biochar of a finer particle size ≤ 1mm resulted in a 7% reduction (although not significant, p&gt;0.05) in the priority PAH groups (2-6 ringed compounds) for the nutrient and biodiesel-amended microcosms compared to the non-biochar experiments while a 4% decrease (p&gt;0.5) was also observed for the biochar amended controls compared to their non-biochar category. In a stepwise treatment approach, the 2-6 ring PAHs in the biodiesel amended microcosms were reduced by 4-16% (p&gt;0.5), while decrease was seen only for 3-5 ring compounds in the nutrient amended experiments. The biochar amended control also showed a 6-7% (p&gt;0.5) reduction in the 4-6 ring PAHs. However, after 30 days of biochar amendment with a larger particle size &gt;1mm, increased concentrations in PAHs was noticed. The biodiesel-amended microcosms had 48% increased levels in the total 16 USEPA PAHs compared to their non biochar amended samples, while 19% increase was observed for the nutrient amended experiments relative to their non-biochar experiments. In all of these experiments, the PAH groups (2-6 ringed) showed increased concentrations in the biochar amended samples. The observation of reductions in the PAH groups of the 16 USEPA pollutants in soil amended with finer particles of this carbonaceous material, showed the likely effect of particle size on the sequestration ability of biochar in soil amendment techniques. Increased concentrations of PAHs seen after amendment with larger particle size of biochar could be due to the possible desorption of these pollutants during the extraction procedure employed prior to measurement. Although the reductions in residual PAH concentrations recorded after biochar amendment were not statistically significant, the non-interference of biochar in the visible growth of fungal hyphae and moulds in the biodiesel treated microcosms and the observed slight reductions in the PAH groups of the 16 USEPA pollutants in the soil amended with finer particles of biochar, compared to the non-treated microcosms, showed the potential of biochar amendment in bioremediation studies. Also prolonged contact and incubation time, following biochar amendment are likely determinant factors for the effectiveness of this amendment technique.
Pre-and Post Stimulation Diagnostics using Spectral Noise Logging. Case Study.
Authors: Volkov M. , Ellis R. , Khabibullin M , Uralsky S. 
Published: October 2018

Abstract
Tight or damaged reservoir sections often require stimulation to adequately perform. These sections can be identified as the well is drilled using LWD measurements and after drilling using open-hole wireline tools (RFTs, borehole imaging, and petrophysical logs). After the completion is run it is often impossible to make these measurements again, meaning that when sections are stimulated the only way to gauge stimulation effectivity is by measuring the change in flow rate within the completion, e.g. through a frac port. The physical reservoir response is not realized. Spectral Noise Logging can be used before and after each stage of a stimulation job to evaluate this response.
SNL distinguishes between matrix and fracture contribution (G. Galli, 2015) to flow allowing assessment of both hydraulic fracturing stimulation and acidizing. Acquiring behind pipe flow profile before the first stimulation stage will provide the baseline. SNL reservoir flow profile can be compared to open-hole logs (e.g. borehole imaging) and used to calibrate them with flow activity as the reference e.g. fractures identified from a formation imager can be seen and categorized as flowing or not flowing (Arthur Aslanyan, 2015). Logging SNL after the first stage of stimulation reveals how the reservoir responds, e.g. improved or new flow through existing fractures (comparing with borehole images), the appearance of new active fractures or change in matrix flow activity. If different stimulation strategies are implemented in the same well or reservoir, SNL can be used to assess and compare the effectiveness of each, resulting in the identification of an optimum stimulation technique.
How effective a stimulation job is largely dependant on the conformance of the completion of the job. If two zones have been targeted with some volume of a stimulation fluid, but a portion of this fluid leaks off to adjacent zones (e.g. through leaking packers) this will impact the degree to which the target zones react. Evaluating completion integrity is therefore crucial to understanding the effectiveness of a stimulation technique. Spectral Noise Logging is used to detect such leaks (Ihab Nabil Mohamed, 2012) making it integral to a wholistic approach in diagnosing stimulation effectivity. Furthermore, for many cases, well conditions render conventional PLT data useless (e.g. cross-flows dominate temperature profile, asphaltenes/solids affect spinner data) so noise data is the only measurement that can represent reservoir activity.
This paper will give such examples where SNL has been used to evaluate the effectiveness of stimulation jobs.
Future Implications of Global Renewable and Unconventional Energy Development on Nigerian Petroleum Sector
Authors: Onyije Israel Jackson , Nwaozuzu Chijioke , Iledare Omowumi 
Published: October 2018

Abstract
One of the most critical advances in the energy sector of the 21st century is the surge in technological developments that made renewable and unconventional (shale oil, shale gas) economically viable energy sources. These developments, in addition to environmental concerns and the quest for sustainable development precipitated a flux in global energy demand and supply dynamics, with huge implications on energy (petroleum) prices. Nigeria is one of the major petroleum exporting countries, whose economy depends almost exclusively on oil (accounting for nearly 90% of total foreign trade, and 80% of foreign exchange revenue), even though the sector contributes less than 20% to national gross domestic product. Presently, the nation is struggling to gain a quantum leap from the current economic recession orchestrated in part, by the slump in global oil price since mid-2014. This negative impact on the economy signal potentials of more severe consequences in the future, especially as major oil consuming economies are realigning their energy policies in favor of low carbon economy. Providentially, it is important to assess the dynamism in the global energy landscape, with a view to furnishing Nigeria's economic and policy makers with information adequate for situating the country on the right pedestal so as to remain relevant both regionally and globally. This is the object of the present study. We use available global statistics (from IEA, US EIA, OPEC and NNPC) and scenarios of energy supply & demand dynamics, to assess the implication for the Nigerian oil and gas sector, as well as the potential market opportunities available for the country. Our analysis showed Nigeria's oil and gas export may face stiff competition in the international oil market. The study recommended diversification of revenue sources; and also energy alliance opportunities, especially with high energy consuming economies like India.
Optimizing Water Injection Operational Parameters for Improved Oil Recovery
Authors: Aigbogun Justifed Feyi , Fusier Francis , Esene Cleverson Ebeagbor 
Published: October 2018

Abstract
The demand for energy has been on a steady rise and oil production from world reserves remains the major source of energy generation; therefore, primary recovery methods alone are insufficient to sustain economic oil production. By supplementing the natural energy of the reservoir through secondary recovery techniques, an incremental recovery factor ranging from 15% to 25% usually can be achieved. This makes water injection feasible and economically attractive as it would allow for increased production rates.
This paper is focused on the incremental recovery that can possibly be achieved by optimizing the operational parameters of water injection. A reservoir in the Niger Delta region of Nigeria, Reservoir OD-50 was used to illustrate this. Reservoir OD-50 has an estimated STOIIP of 267MMbbls and a recovery factor of 32%, and is planned to be developed alongside water injection for pressure maintenance and improved recovery. This work was done to determine the additional oil can be produced by optimizing the operational parameters affecting the efficiency of water injection.
Parameters such as injection rate, time of commencement of injection, contributing drain lengths, well types, bottom hole pressures and tubing head pressures were studied as sensitivities in this work and an optimized case with the most influential parameters on the recovery was obtained. The optimized case resulted in an additional oil recovery factor of 1% and from the economic analyses, the NPV was increased from $293.06M to $305.25M, the IRR from 27.1% to 27.4%, and the PI from 1.44 to 1.46.
Bubblepoint Pressure Mathematical Modelling for Nigeria Crude Oil
Authors: Adeeyo Yisa Ademola 
Published: October 2018

Abstract
Bubblepoint pressure is a fundamental factor in reservoir management and reservoir engineering calculations. Ideally, the lab measurements of reservoir fluid properties of samples collected from the bottom of the wellbore or from the surface are the primary sources of bubblepoint pressure. Such experimental data are, however, not always available because of one or more of such reasons as samples collected are not reliable or samples have not been taken because of cost saving. In this circumstance the notable among published empirical models are perused and used to predict bubblepoint pressure. These empirical models were developed by fitting equations for a certain range of PVT parameters using large sets of measurements of these parameters. Unfortunately, some of these correlations are incorrect, especially when used to predict bubblepoint pressure of crude from a different region and or different range of crude characteristics.
This study examined the available models using classic statistic criteria and developed a new bubblepoint pressure model.
I have used more than 2580 unpublished PVT data sets from different locations in Nigeria in developing the model. The model development workflow considered the impact of each independent variable on the bubblepoint pressure, pairwise plots to show evidence of nonlinearity, stepwise regression dimensionality reduction (backward selection method) and variance. Model parameter estimation was based on a search method from the optimization that minimized the norm of residual vector/error. The new model was subjected to standard statistical tests. These tests established logical validity as well as the statistical measures of the suitability of the model.
The results of the comparative study between existing correlations and new model show that the new model provides a more remarkable and reliable performance.
Performance Assessment of Nigeria E&P Operators Using Data Envelopment Analysis DEA
Authors: Idowu Joseph Adekunle , Iledare Omowunmi O. , Adeogun Oyebimpe , Echendu Joseph C. 
Published: October 2018

Abstract
The paper aims to; estimate relative technical efficiency (RTE) for each of the Nigeria 32 active Operators using vDEA model, rank the performance of the Operators considering output orientation, categorize each of the Operators into its respective return to scale (RTS) group using Non-Increasing Return to Scale model (NIRTSM) and suggest necessary policies that could improve the performance of the Operators.
The approach is based on variable return to scale assumption of DEA model framework (vDEA). Based on this, four variables were considered; two inputs, petroleum reserves in million BOE and Number of producing Wells and two outputs; total annual oil production in million BBLS, total annual gas production in million SCF. vDEA model assumes operational variability due to constraints such as: projects financing, competition, government policies, operational terrains, etc. A dual linear programming model (DLPM) is formulated and a Microsoft excel solver aided with a visual basic application (VBA) is used to generate RTE for each Operator simultaneously. RTS indexes are estimated using output oriented NIRTSM. The relationship between the two models' results is used to categorize each Operator into different production scale group.
The empirical results reveal a decreasing trend in the Operators' RTEs from 2010 to 2016. Twelve (12) of the Operators were operating on efficient production frontier within the period under investigation. Based on this, Operators were classified into three different production scale group. Eight (8 or 25%) were operating on decreasing return to scale (DRTS), Six (6 or 19%) on constant return to scale (CRTS) while the remaining Eighteen (18 or 56%) were on increasing return to scale (IRTS). Significantly, it is discovered that more than 80% of the JV Operators have been operating on DRTS.
Consequently, the paper provides information on RTEs of the 32 active upstream Operators in Nigeria considering more realistic assumptions as recommended, (Idowu and Iledare, 2018). Operators performance is ranked based on estimated RTE indexes as well as production maximization consideration. The paper proposes policies such as: splitting of JVs companies into two or more to minimize bureaucracies and facilitate new efficiency-oriented ideas, merging of companies under IRTS to enhance internal growth and embarking on aggressive reserves growth policy to increase the reserves base of the 6 Operators on CRTS.
Evaluating and Inhibiting Gum Formation Tendencies in Gas Condensates
Authors: Bamidele Taiwo , Onuigbo-Nweze Chy , Osuagwu Michael , Azubuike Achara , Joel Ogbonna , Onyewuchi Akaranta 
Published: October 2018

Abstract
A report is presented on the evaluation of gum formation tendencies of natural gas condensates from two gas fields in the Niger Delta region of Nigeria. Following reports that certain condensates from the region have high gum formation tendencies and thus their market prices devalued, a study was embarked upon to evaluate and inhibit the formation tendencies of these condensates, if any. The reports indicated that there was general consternation around high unwashed gum contents and this parameter was sometimes considered in conjunction with the washed gum contents when devaluing the condensates in question.
To investigate the suitability of current evaluation methods, a review of ASTM D381, the gum test method developed for gasoline and jet fuels which is now being applied to gas condensates, was carried out. Further tests such as fingerprinting, boiling ranges and asphaltene content were also carried out. To investigate the effectiveness of anti-oxidant injection in inhibiting gum formation, two products were selected and injected into a condensate sample at varying concentrations and the gum content of resulting mixture was tested using ASTM D381.
The results show that while ASTM D381 was developed for gasoline and jet fuels, its use for these products is not firmly established and thus, its extension to gas condensates is even more uncertain. This is because heavy hydrocarbon fractions which are not present in processed fuels are present in condensates. Thus, the typical values of unwashed gum content in refined liquids cannot be expected of condensates where they are bound to be significantly higher. For the samples under-investigation, confirmatory tests using boiling ranges as a complement to the n-heptane washing step of ASTM D381 supported the observation that &gt;60% of the unwashed residue was not gum, but instead naturally-occurring heavy hydrocarbon fractions which would not normally evaporate under the test conditions of ASTM D381. Furthermore, the use of antioxidants at high concentrations showed a decrease in the washed gum content. However, the decrease was only achieved at very high concentrations.
Insights made from this study presents the industry with evidence that the existing method for evaluating gum content in only applicable to gas condensates as far as the washed gum content in concerned. Condensate quality concerns based on unwashed gum content are unfounded and thus, should not be considered by suppliers and buyers of condensates. Furthermore, it is recommended that the further work be carried out to develop and/or evaluate antioxidant chemistries that are cost-effective and can perform at lower concentrations.