bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Waterflood Oil Recovery under Different Oil Viscosities using Siljan and Sherwood Oils
Authors: Okoro Franklin 
Published: August 2020

Abstract
Two-phase flow through rock is controlled primarily by the pore structure, oil viscosities, wettability, and the flow. This paper considers the impact of oil viscosities on waterflood oil recovery from oil/water/rock systems, focusing specifically on mixed wet conditions characteristic of oil reservoirs. In mixed-wet reservoirs, the wettability of the surface of the grains that constitute the rock are heterogeneous at the pore scale and sub-pore scale. This heterogeneity is attributed to the preferential migration of crude oil into larger pores in initially water-wet (hydrophilic) reservoirs, and the subsequent alteration of oil-contacted grain surfaces to a less water-wet or an oil-wet (hydrophobic) state through, e.g., asphaltene adsorption. In this study, the wettability alteration to mixed-wet conditions was achieved by leaving the oil in the medium for 2 hours to render the grains less water-wet prior to waterflooding, this is known as aging. This work was restricted to a comparison of two oils with varying viscosities; Siljan and Sherwood oils. Image processing (flow visualization) technique was applied to analyse and compare the displacement efficiency in each experiment using an automated code developed with MATLAB. Experimental results suggested that long duration of aging (wettability alteration) alters the wetting system of the medium saturated with a light oil from a water-wet system to a more oil-wet system and results to a low waterflood oil recovery efficiency when flooded with brine whereas the long duration of aging is more favourable to heavy crude oil system when flooded with brine. However, the fractional water cut for the heavy oil system was higher as expected than that of the light-medium oil system.
Development of a Novel Compressibility Factor Correlation for High Pressure-High Temperature HPHT Reservoirs using Stochastic and Robust Optimization Approach
Authors: Ogbunike Jude , Adeyemi Temitayo 
Published: August 2020

Abstract
Accurate estimation of compressibility factor is of great importance in predicting the performance of gas reservoirs using the material balance approach and also in the designing of gas pipelines and flowlines. Over the years, several correlations for estimating gas compressibility factor have been developed. However, these correlations have not been so successful in predicting the compressibility factor for High pressure-High temperature (HPHT) reservoirs and this explains why the industry still relies on the expensive and time-consuming constant volume depletion (CVD) approach. Therefore, this paper presents a correlation suitable for estimating the compressibility factor for high pressure-high temperature (HPHT) reservoirs using stochastic and robust optimization approach with Gaussian probability distribution. The results obtained shows that the correlation outperforms other pre-existing correlations within the range of pressures and temperatures considered.
Investigating the Correlation between Water Saturation obtained from Cased-Hole Saturation Tool Measurements and Produced Water Cut in Strong Water Drive Reservoirs
Authors: Pius Timothy O. , Olamigoke Olugbenga 
Published: August 2020

Abstract
The correlation between the produced water cut and average water saturation around the perforation obtained from Cased-Hole Saturation Tool (CHST) measurements is evaluated in this paper. The motivation for this study is to enable significant financial savings which would accrue by the need for less CHST logging runs for effective Reservoir Fluids Management provided average water saturation can be quantified in terms of produced water cut, the water perforation coverage and the wellbore completion string parameters such as perforation thickness, and deviation angle.
Average water saturation and perforation water coverage, was determined by analyzing CHST logs block by block obtained using CHST tools in two different petroleum provinces (Nigeria Joint Venture Area and North Sea Basin). For each well logged, well test data or Production Logging Tool data, wellbore deviation survey and the completion schematic were obtained. The datasets from each region were split in two categories – well shut-in for less than four months prior to CHST log measurements and wells shut-in for more than 4 months. Regression analysis was used to investigate the correlation between CHST log determined parameters and other flowing and static wellbore parameters for wells without any history of damage or complex water production mechanisms.
The results obtained indicate that for wells in the Niger Delta with large perforation intervals (&gt; 30 ft), produced water cut strongly correlates with average water saturation while for wells in the North Sea Basin with short perforation intervals (10 - 30ft) the average water saturation correlates strongly with both water cut and the perforation interval thickness. It was apparent that for the wells shut-in for periods exceeding four months no empirical relationships could be established. Heterogeneity in petrophysical property distribution and borehole reinvasion are suspected to be responsible for deviation from the correlation between produced water cut and average water saturation.
The Application of Investigative Workflows for Sour Field Mitigation and Remediation
Authors: Harper Christopher , Michael Nnochiri , Yan Zheng , Victor Okowi , Bamisebi Adetloye 
Published: August 2020

Abstract
Reservoir souring is simply defined as the predicted or observed increase in production of sulphide in oil, water or gas phase. The potential causes are far less simply defined, and can, in many cases, lead to a significant disruption to operations through concerns over HS&E, integrity and process efficiency. The consequences of sour production can be far reaching, and almost always expensive, perhaps to the point of making a field un-economical to produce.
One of the reasons for this is that, in many cases the response to souring is to mitigate, long term and short term, the consequences of souring, rather than the cause of souring. This paper examines the application of both high level and detailed investigation workflows which have led to significant improvements in understanding both the risks associated with souring and the most techno-economically feasible long term and short term mitigations of both causes and effects.
The aim of the workflow is to define causes and develop solutions to either mitigate souring and/or the effects of souring, maximising the techno-economic benefit to the operator and reducing HS&E risks as much as possible. The workflows themselves are phased and flexible, they aim to examine pre-existing data, examine their validity, and/or collect new data to identify the probable causes of souring in each specific case. Once the cause(s) have been defined it then becomes possible to estimate worst case souring potential and integrity threat based upon biochemical and geochemical interactions, phase behaviours and the physical condtions for either microbiological and/or non-microbiological throughout the system.
This approach has been applied numerous times to great effect in sub-sahran Africa, North America and Europe.
Interpretation of 3D Seismic Data for Prospectivity of Underexplored Deep Formations in Pateke Field, Niger Delta Basin, Nigeria
Authors: Nwike I. S. , Onwuemesi A. G. , Nwozor K. K. , Onuba L. N. 
Published: August 2020

Abstract
Overlooked prospects and underexplored fields in the Niger Delta Basin continue to attract the attention of many stakeholders in the industry as the quest to achieve the national 40 billion barrels oil reserve target continues to gain momentum. A key area of interest is that many wells drilled earlier in the basin were limitedlargely by technology from probing deeper formations. With the availability of 3D seismic data, improved subsurface knowledge, more efficient interpretation tools and skills, this study reevaluated the hydrocarbon potentials of the economically strategic ‘Pateke’ field in the Coastal Swamp Depobelt where the deepest well was drilled to a total depth of 8950 feet (2728 meters). Thereevaluation approach involved high precision fault and horizon mapping, seismic attribute extraction and analysis using the Petrel platform. The interpretation shows the structural framework of the field to be constituted by five faults with two major faults trending east – west and northwest – southeast respectively, thus dividing the field into three fault blocks. Integration of Root Mean Square (RMS) Amplitude, Envelope and Sweetness seismic volume attributes suggest probable hydrocarbon accumulations within the fault blocksthat lie far beneath the reach of the present wells in the field. The implication of this result is that the full potentials of ‘Pateke’ field are yet to be achieved considering the positive indications of economically recoverable hydrocarbons in the deeper sections of the field.
Determination of Optimal Well Location in Bounded Reservoirs Using the Dimensionless Pressure Derivative
Authors: Ojah Michael , Enuma Emumena , Onah Collins , Prince Oduh , Adewole Steve 
Published: August 2020

Abstract
When a reservoir is bounded, well productivity is affected in the long time according to the nature of the boundary. The length of time for oil production is strongly affected by well location with respect to the boundary, whether the boundaries are single, paired and vertical or paired and inclined. It therefore becomes important that well location is guided to achieve prolong oil production. The guide may be achieved from solution to a specific flow equation describing pressure distribution. The solution prescribes rates and well location for available reservoir system properties.
In this paper, dimensionless pressure derivatives of a vertical oil well are studied to search for optium well location that can guarantee satisfactory oil production without premature influence of the external boundaries. The external boundaries are sealing and are considered to be inclined. The solution to this dimensionless diffusivity equation is utilized. The derivatives are computed from the total dimensionless pressure expression summing all the image wells by superposition principle. The Python and Excel softwares were deployed to compute all the dimensionless pressures for the different well designs. Larger magnitudes of dimensionless pressure derivatives would indicate higher oil production for any well design and inclination of the sealing faults.
The optimum well location from the sealing faults is inversely proportional to the inclined angles. This implies that nearer wells to faults produce optimally at a given time of production. Furthermore, the relationship between well distance and productivity has no maximum or minimum points. Therefore there is no particular optimum location distance from the faults for optimum productivity. Optimum well location for sealing boundaries depends on many factors, such as production profile, well design, faults angle, fluid type and lease size. Furthermore, it was also observed that the wellbore radius has no significant effect on the dimensionless pressure derivative, optimum well location and the optimum time of production.
Effects of Additive Concentrations on Cement Rheology at Different Temperature Conditions
Authors: Ikpeka Princewill , Benedict Ugochukwu , Utojiuba Davida , Odo Jude , Uzuegbu Godson 
Published: August 2020

Abstract
Previous studies suggest that the rheology of cement slurries used during oil well cementing operations is an explicit function of temperature, additive type & concentration and cement grade. This study analyzes the effect of these factors on a water based mud (WBM). 27 experiments were conducted by varying three additive concentrations; retarders, fluid loss additives and dispersants. Shear rate and stress were then experimentally determined at varying temperature and concentration, while the plastic viscosity (PV) and yield point (YP) were determined analytically. The slurries were conditioned as set out in API RP 10B-2. Linear regression was used to build models describing the effect of temperature and additive concentration on PV and YP of the cement slurry. Results from the analysis reveal that for a temperature increase of 125% and Retarder concentration increase of 200%, there were significant decline in PV (-41%) and YP (-44%). Whereas increasing the Fluid loss additive by 100% caused a significant increase in YP (+51%) and relatively insignificant increase in PV (+4.4%). This study concludes that the coupled effect of increasing temperature and retarder concentrations of cement slurries has a significant negative impact on both the YP and PV.
Optimized Salinity Water Flooding as an Improved Oil Recovery IOR Scheme in the Niger Delta
Authors: Alaigba David , Oduwa Onaiwu , Ohenhen Ikponmwosa , Olafuyi Olalekan 
Published: August 2020

Abstract
Following on from the work by Tang and Morrow in 1998, enormous progress has been made in the development of low salinity water flooding for improved oil recovery, (IOR). This paper has assessed the applicability of modified salinity as an IOR scheme in the Niger Delta. A laboratory approach which entailed the use of crude oil, brine and core plugs from fields X and Z located in the Niger Delta was adopted. Several options were assessed: progressive dilution of the injected brine, variation of concentration of divalent cations in the injection fluid, high salinity flooding followed by low salinity flooding (HSF, LSF) and variation of low salinity slug size. The results obtained are very promising as additional recoveries in the order of +5% to 21% were obtained from this work. Based on the promising results of this on-going research, recommendations on future improvements were also outlined.
Experimental Characterization of Palm Kernel Shell as Wellbore Strengthening Material for Depleted and Loss Circulation Zones
Authors: Emmanuel Ayodele , Dosunmu Adewale 
Published: August 2020

Abstract
With a continued growth in the discovering of new reserves at deeper depths in mature fields, drilling through the depleted and already producing zones is already posing a loss circulation problem as well as other wellbore instability problems such as stuck pipe. Considering the cost of loss circulation materials and its effectiveness the need to source materials locally for LCMs becomes imperative. This research work investigated palm kernel shell as a local material to be used as loss circulation material, the processed palm kernel shell was sieved into different particle sizes and added in various mass ratio to the formulated mud. The mud weight, filtration test and permeability plugging test was done to experimentally characterize the mud based on its effectiveness as a loss circulation material. Palm kernel shell with blends of other industry loss circulation material was also considered to ascertain the blended LCMs effectiveness as compared to the palm kernel shell mud samples. From the experiments conducted, the mud weight of palm kernel shell mud samples ranges from 11ppg to 11.4ppg in different particle size distribution. The total filtrate loss and the filter cake thickness ranges between 5.0ml to 8.6ml and 1mm/32-inch to 2mm/32-inch respectively. The permeability plugging test of the Palm kernel shell mud samples has a range of total filtrate volume of 8.9 ml to 11ml, as well as filter cake thickness of 3mm/16-inch to 4.5mm/16-inch. In a comparative analysis, the blend LCMs, i.e. the palm kernel shell and Mica, palm kernel shell and graphite have a better sealing and filtrate loss properties than the palm kernel shell mud samples. It is therefore recommended that more research should be carried out on the blends of palm kernel shell and other LCMs as it will be cost effective when compared to the imported LCMs.
The Nigeria Gas Landscape: Implications for Economic Development
Authors: Gbakon Kaase , Ojaraida Lolo 
Published: August 2020

Abstract
The gas supply system in Nigeria is today skewed to favour exports over domestic utilization, thus leaving unfulfilled what have always been the twin objectives of Nigeria’s gas policies–robust foreign exchange earner and stimulation of the national economy. So far as this review has shown, neither of these objectives has been achieved – yet. FG earnings from export oriented NLNG at $43Billion in the last twenty years is about the same quantum that is on average distributed annually to the states via the Federal Allocation Accounts Committee (FAAC). While domestic gas supply is sufficient to generate only 16W of power per Capita – the lowest in a peer comparison of select African countries.
However, it has not always been the case that gas enjoyed a prime focus in the energy policy framework of Nigeria as it does today. Gas is receiving increasingly more attention as noted by deliberate policy actions taken at various times – the enactment of the NLNG fiscal act in 1989, introduction of the Associated Gas Framework Agreement (AGFA) provision in the PPTA in 1998, the incentives for gas utilization projects in the Corporate Income Tax Act (CITA) introduced in 1998 and 1999, Gas Pricing policy of 2008, the National Gas Policy framework of 2016 and more recently the Flare Gas Regulations of 2018 – all targeted at the different components of the gas value chain – upstream production, market sector development, pricing, off-take, and related downstream utilization.
Global increase in natural gas utilization rides on the back of geopolitical dynamics such as climate change action, growth in emerging economies, and increased US shale gas production. Contextualizing Nigeria’s gas polices against the wider canvass of geopolitical concerns which include the interplay with Nigeria’s energy security suggests that Nigeria will have to take deliberate policy steps – from upstream gas fiscal terms reforms, through to pricing reform, project prioritization, strategic gas portfolio allocation to refocus effort on channelling gas to deliver a "harder domestic punch."
Raising the Sleeping Giants: Restarting of Alpha & Beta Fields World-Class WRFM Collaboration
Authors: Sa'ad Abdul-Wahab , Ayeni Olumide , Unukogbon Obaro , Nwosu Obiora , Imorame Imonitie 
Published: August 2020

Abstract
The importance of Wells, Reservoir, and Facility Management in the life of producing Oil and Gas assets cannot be overemphasized. Several authors in the past have highlighted the significant contributions WRFM practice and process have to the ultimate recovery of matured assets. WRFM serves as a stop-gap to redevelopment in areas of cash crunch, whereby active WRFM practice arrests severe natural decline in production. Onshore assets comprising of fields Alpha and Beta are operated by Shell Petroleum Development Company (SPDC). These assets have been operated for over 30 years, rising water cut & high gas-oil ratio production and facility downtime risks have impacted oil recovery. This work showcases the application of WRFM at the re-startup of production in these fields post shut-in for almost 5 years. Effective and deliberate application WRFM processes and practices woven together in the WRFM Plan not only ensure an efficient restart of the facility but the ability to ramp production while maintaining the intricate balance of good reservoir management. The paper will highlight the best WRFM practices which enabled the resumption of production at a lower water rate compared to when the field was shut and maintain this higher net oil for a prolonged time. Also highlighted are opportunity identification and implementation in-closed wells and effective collaboration across disciplines to ensure a safe and efficient restart of production facilities.
Estimating the Quantity of Recoverable Heat in a Geothermal Reservoir in Nigeria
Authors: Okeifufe Nnamdi Francis , Izuwa N. C. , Nwogu Ngozi 
Published: August 2020

Abstract
The quest for cleaner sources of energy in the world today has paved way for scientists and researchers to delve into renewable energies like the geothermal energy. Researches on the enormous potential that a geothermal reservoir could posses are currently underway. However, there is limited information on the quantity and quality of geothermal reserves in Nigeria. Extraction of this geothermal heat will improve power generation and the availability of scarce electricity in Nigeria. This work is aimed at using a mathematical model to estimate the quantity of recoverable heat by first estimating the total heat in place and then the heat losses associated with heat transfer in a wellbore. In this work, we were able to ascertain the heat in place as well as recoverable geothermal heat for geothermal regions in Nigeria having a temperature-at-a depth range of 50°C – 110°C and also a higher temperature-at-a depth range of 150°C – 250°C. Heat losses were considered for pipe tubings with 1 inch, 2 inches and, 3 inches diameter. A higher recoverable of 92% was gotten when the 1 inch pipe diameter was used. 87% and 76% recoverable were also gotten when the 2 inches and 3 inches diameters were used respectively. Nigeria has the potential of generating 74Megawatts of electricity from just one geothermal reservoir which could provide electricity for villages and small towns.
New Non-SARA-Based Correlations for Predicting Asphaltene Deposition
Authors: Sulaimon Aliyu Adebayo , Umar Abubakar Abubakar , Sulaimon Abdul-Azeez Oladimeji , Masri Asiah Nusaibah , Bello Kelani Olafinhan 
Published: August 2020

Abstract
Asphaltene deposition constitutes a major flow assurance challenge during oil production. Several attempts have been made to predict asphaltene stability using SARA analysis, which is usually expensive and time-consuming. Therefore, we have developed new SARA-independent correlations for the colloidal instability index (CII) and the refractive index (RI) as functions of oil density. The new density-based CII or DBCII is proven to be reliable with an average absolute relative error (AARE) of 0.1428, standard deviation (SD) of 0.1902 and a correlation coefficient R2 of 0.9520. Similarly, density-based RI or DBRI has been validated with an AARE of 0.0037 and SD of 0.0044. Two new deposition envelops have been developed with different criteria. The stable regions are characterized by DBCII lesser than 1.1 and DBRI greater than 1.525 while the unstable zones are defined when DBCII is greater than 1.8 and DBRI lesser than 1.503. The metastable region is identified within the limits of stable and unstable criteria. Comparative analyses have shown that the new correlations are simpler, cheaper and more accurate than the existing SARA-fractions-dependent-RI correlation and molecular-weight-dependent CII correlation.
Model for Estimating Optimum Hydraulic Fracture Geometry in Gas Condensate Reservoir
Authors: Odo Jude Emeka , Ikpeka Princewill Maduabuchi , Okereke Ndubuisi Uchechukwu , Odo Blessing Chidinma , Idika Uduma Uduma , Ofoegbu Daniel Chukwuebuka 
Published: August 2020

Abstract
A new analytical model for optimizing hydraulic fracture conductivity has been proposed by modifying the model developed by a researcher using the formula obtained from classical 2D Perkins-Kern-Nordgren (PKN) model as a function of proppant viscosity and the young modulus (rock compaction). This study shows that fracture conductivity depends on penetration ratio and fracture conductivity decreases as penetration ratio increases and this is due to the increase in overburden pressure of the rock and viscosity of the proppant fluid and this lead to reduction in productivity. It was proposed that productivity can be increased by increasing the fracture pressure and the viscosity of the fluid depending on the type of formation.