bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacterial Community Profiling and Predictive Functional Gene Analysis during Petroleum Biodegradation
Authors: Chikere Chioma Blaise , Ezekoye Charles Chibueze , Okpokwasili Gideon Chijioke
Published: August 2020

Bacterial functional diversity in crude oil-polluted site undergoing remediation by enhanced natural attenuation (RENA) was monitored over an 8-week period. Soil samples were collected from the polluted site (>5,000mg/kg of TPH) at various phases of bioremediation while the control (unpolluted soil) was taken 80 meters away from the polluted site. Next generation sequencing on Illumina MiSeq platform was used to characterize the bacterial community composition. Functions of different operational taxonomic units (OTUs) and proportions of functional bacterial groups involved in each step of biodegradation were predicted using Kyoto encyclopaedia of genes and genomes (KEGG) and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt). Principal component analysis (PCoA) of the functional genes was also carried out for statistical inferences. The predicted functional genes indicated the presence of genes responsible for benzoate, DDT, dioxin, fluorobenzoate, naphthalene, nitrotoluene, polyaromatic hydrocarbons, styrene, toluene and xylene degradation. Sample obtained post-bioremediation showed significant (P ≤ 0.05) differences in functional genes responsible for benzoate, xylene, ethyl benzene, valine, leucine and isoleucine, nitrotoluene, aminobenzoate and DDT degradation when compared with baseline (pre-remediation), polluted soil (PS) during remediation on days 0, 9, and 29. PCoA revealed that PS on days 0, 9, and baseline had similar functional genes spread while functional genes in PS days 29, 36 and 56 increased progressively with time. The top five known petroleum degrading bacterial phyla identified included Proteobacteria, Actinobacteria, Acidobacteria, Cyanobacteria and Firmicutes. The study area harboured a variety of bacteria with metabolic capacities for pollutant degradation. Functional genes related to petroleum degradation were widely distributed and found to be abundant especially in zones with higher pollution levels. Moreover, the study provided insights into in situ bacterial functional structures in crude oil-impacted site and unraveled the linkages between bacterial communities and environmental variables which are important in the application of bioremediation.
Core Residual Oil Analysis and Integration to the Dynamic Model
Authors: Cruz Mauro , Harrison Peter , Braga Jose , Martins Fernando , Sanuca Carlos
Published: August 2020

Obtaining a core behind the flood front appears to be the most appropriate way to directly measure residual oil saturation. Conventional analysis based on resistivity logs requires the water salinity to be known. As the pore space behind the flood front contains a mix of formation, aquifer and injected water with significantly different salinities, water saturation calculated therefore will have a large uncertainty associated with it.

While e-line NMR and other conventional logs can give indirect estimates of residual saturation without any calibration, Direct measurements to overtake this challenge can only be carried out on a core. In this paper, we present a core behind flood front that was acquired in a BP Angola field. The core analysis provided a direct measure of the residual oil saturation throughout the cored interval providing information about vertical sweep efficiency as well as the value of the residual oil saturation.

The value added through the acquisition of core was considered to have reduced the risk of inefficient oil recovery by:

Understanding the efficiency of the sweep in channel edges Understanding rock properties behind the flood front Direct determination of residual oil saturation. Assuring reserves in place and Remaining Reservoir management strategy by Water injection strategy and Improve understanding of reservoir will lead to better depletion management – targeting of infill wells. Determine tertiary oil recovery techniques. Aid calibration of water and oil saturations in simulation models. Assist with production performance prediction and reduced surveillance. Opportunity to cut a behind the flood front core in channel edges facies (low NTG).
Efficient Formation Testing and Data Interpretation Using Advanced Probes and In-Situ Fluid Property Evaluation
Authors: Frank Søren , Robinson Anna , Ostroff Gary M. , Khong Chee Kin , Dunlap James , Roche Sebastien , Jackson Richard
Published: August 2020

Deepwater environments pose significant challenges in design and execution of comprehensive yet cost effective formation testing programs. For a recent deepwater appraisal well, pre-job modeling, advanced formation testing technologies, and in-situ fluid analysis were utilized to design and execute a formation testing program which provided significant improvement in the quality of data and fluid samples acquired, as well as significantly reduced time required for testing.

Multiple PVT and bulk samples were collected with an advanced focused sampling probe, providing an average pumping time of 3.5 hours per sampling depth with sample contamination as low as 1%. This compared favorably to nearly 9 hours per sample depth, double the volume of fluid pumped, and fluid contaminations of 8-14% observed in the previous appraisal well using an unfocused probe.

The low contamination improved the accuracy of real time Downhole Fluid Analysis (DFA) measurements such as density and viscosity, hydrocarbon composition and GOR performed with an advanced in-situ fluid analyzer. Fluorescence and reflectance detectors within the same tool were used to evaluate fluid phase state.

Another important component of the acquisition were several Interval Pressure Transient Tests (IPTT) performed to evaluate horizontal and vertical permeability. An advanced 3D radial probe was selected over a conventional Dual Packer to perform these tests. The 3D radial probe was more time-efficient, provided better quality buildup data including vertical interference data (VIT), and presented lower operational risk. Real time measurement of fluid viscosity enabled the immediate estimation of permeability. Zonal permeability and permeability anisotropy (kv/kh) for the tested intervals were interpreted from the pressure transient responses of the radial probe and observation probe
Economics and the Energy Sector in Nigeria
Authors: Nwatu Victor Okechukwu , Ezenwa Emmanuel Nnaemeka
Published: August 2020

The study examined the economics and energy sectors in Nigeria by analysing the development of energy sector in Nigeria, which includes crude oil, natural gas, electricity. The work focused on these energy resources; crude oil, natural gas and electricity given that they cover 80 percent of the energy mix in Nigeria. The study gave insight as it concerns dynamics, challenges, and regulation affecting the energy sector with recommendations that can foster economic growth.
Performance Evaluation of Natural Gas Value Chain in Nigeria
Authors: Ojaraida Lolo , Iledare Omowumi , Ajienka Joseph
Published: August 2020

Natural gas resource abounds significantly in Nigeria. Thus, the description of Nigeria as a prolific gas province with pockets of oil is not conjectural. However, little effort in terms of gas exploration and production is evident. This has made the gas sector a focal point with respect to resource development for sustainable energy and national development economy. This paper evaluates natural gas value chain in Nigeria. The purpose is to analyze the relative technical efficiency of the value chain of natural gas industry in Nigeria from 2013 to 2017. Data Envelopment Analysis (DEA), a deterministic tool for assessing the efficiencies of decision-making units, provides the fundamental framework applied to analyze the gas industry value chain in this paper. In addition, in order to incorporate data uncertainty, we adopted the uncertainty DEA plus tool to show that for the period under consideration, none of the gas value chain sector is technically efficient, albeit, in a relative sense. The midstream gas sector is the least efficient, while the downstream export gas sales is the most efficient. The DEA results suggest that for Nigeria to meet her economic growth aspirations and become an attractive gas-based industrial nation, pragmatic policy framework to maximize value creation across the gas chain sectors is required. In addition, harmonizing the domestic gas market and the export gas market will bring about value creation for sustainable national development.
Design of Extrusion Machine for Offshore Corrosion-Control Composite Wrap Material Manufacture
Authors: Adisa Ademola , Olatunji Oladipo , Brando Kenneth
Published: August 2020

From time immemorial, corrosion in the offshore environment of the oil and gas industry has consistently plagued smooth operations by introducing huge costs of corrosion control and non-productive time. The corrosion effect is even more pronounced on Deepwater structures such as pipelines, hull decks, handrails, gangways and so on, due to harsh marine environmental exposure. Due to the deteriorating effect of corrosion, the amount spent on surface protection could range from thousand to millions of dollars depending on the extent of corrosion damage. Apart from the repair costs, some of the offshore operations are entirely shutdown before commencement of corrosion control measures which contributes to production downtime and unscheduled volume loss. In this paper, a composite material is presented that is corrosion resistant and can withstand the expected pressure and temperature conditions in the offshore environment. This material extrudes from a specially designed machine that takes wood and plastic wastes as feedstocks in appropriate ratios depending on the area of application on the facility. Upon laboratory analysis, this material has a melting point of 400degF (204degC), and load testing also revealed that at typical offshore condition of pressure ≅ 50bars and at about 100degC, this material would be very suitable for corrosion control. Furthermore, from an economic standpoint, this composite material is extremely cheaper with a cost of 300 USD per foot of pipeline coating compared to about 2000 USD cost using conventional corrosion control materials. In addition, with the implementation of this process, we have realized that negative environmental contribution of plastic wastes to greenhouse gases (GHGs) will be greatly mitigated, reducing the overall levels to about 10%. In conclusion, a cost effective and an environmentally friendly corrosion protection composite wrap has been developed by recycling wood and plastics wastes.
Assessment of Aquifer Susceptibility using Artificial Intelligence: A Case Study of the Warri-Sombreiro Deposits, Niger Delta
Authors: Ojoboh Emuobosa Patience , Ochie Karen Ifeoma , Nwosu Chinedu Joseph
Published: August 2020

An aquifer is a very paramount aspect of the petroleum system and its susceptibility is a function of its ability to be vulnerable to factors such as contaminants, land pollution, subsidence, groundwater quality degradation due to movement of saltwater and so on. The Warri-Sombreiro deposits in the Niger Delta are characterized with unconfined aquifers as part of its petroleum system and studies have been carried out to determine the aquifer vulnerability using the Aquifer Vulnerability Index (AVI) which only considers the thickness and resistivity of the layers, hence, the susceptibility score is not entirely representative of the innate aquifer properties. The thickness and resistivity values in this study were obtained from ten (10) Vertical Electrical Sounding (VES) stations using the Schlumberger configuration. This methodology utilized a database containing the resistivity, conductivity, hydraulic resistance, longitudinal conductance and corresponding acquifer susceptibility rating of the stations. Linear transformation was used to normalize data with high deviations to values between 0.2 and 1, in a bid to prevent perturbation conditions. The transformed data was then trained using the Levenberg-Marquardt training algorithm to build a neural network that estimates the Aquifer Susceptibity Rating. The acquifer was further classified using the Acquifer Susceptibility Rating (ASR) to determine the level of susceptibility. The acquifer susceptibility map was then plotted using the RESIST software and it was determined that 25% of the area had low susceptibility with a clay overburden between 2.0m to 33.9m above the aquifer, 25% of the area had moderate susceptibility with clay overburden of 1.1m and the remaining 50% had high susceptibility and a lower clay overburden. The Neural Network model proved to be statistically efficient in the prediction of the Acquifer Susceptibility Rating as it gave a correlation coefficient of 1 and mean square error of 5.6246 × 10−24.
Geosteering in a Turbidite Lobe Deposit in Deepwater Niger Delta
Authors: Ndokwu Chidi , Okowi Victor , Brock Philip , Imomoh Victor , Amadi Kenneth , Berry Timothy , Osita Humphrey , Ozioko Raphael , Chizea Chukwuka , Agbejule Adekunle , Oteh Benneth , Olagundoye Olatunbosun , Okengwu Kingsley , Acra Jones
Published: August 2020

The knowledge of structural geology and depositional environment plays an important role in the success of any geosteering job. The bedding type, bedding dip and dip direction, faulting, localized folding, lateral facies change and continuity of sand bodies, sand-shale ratio of the deposits are some critical factors to consider in the planning of a geosteering job. These factors determine the predrill geosteering strategy and the real-time decision-making steps. The resolution of seismic data, the limited number of offset wells and their lack of proximity to the planned well, contribute uncertainty to the knowledge of these factors before drilling commences.

This is a case study describing the geosteering of a complex deepwater turbidite reservoir in the Niger Delta. The reservoir is a sandy lobe deposit and is faulted. The well objective was to drain the required intervals in the sand compartments and geosteering was needed to support real-time decision making by estimating the throw of major faults, determining the presence of sub-seismic faults, interpreting near-wellbore structural geology, stating the proximity of conductive boundaries and describing reservoir heterogeneity. The geosteering was successful with the trajectory draining all planned sand bodies, providing improved structural interpretation of the reservoir geology in real time and achieving over 500m of net sand.

The aim of this paper is to review the real-time decisions taken to achieve the well objective of placing a drain section in a sandy lobe deposit, describe the near-wellbore structural geology of a turbidite reservoir in the Niger Delta, and review some geological factors to consider while geosteering in deepwater Niger Delta reservoirs.
Assessing the Impact of Deep Offshore and Inland Basin Production Sharing Contract Ammendments on the Economics of Deep Offshore E&P Assets in Nigeria
Authors: Ogolo Oghenerume , Iledare Omowumi O. , Nzerem Petrus , Okafor Ikechukwu S. , Iloegbunam Emeka , Ekeoma Isaac P.
Published: August 2020

Nigeria recently amended the Deep Offshore and Inland Basins Act. The Act seeks to generate aditional annual revenue of over $1 billion for the government. The 2019 Law seems attractive to the government in the short run in terms of early rent extraction; on one hand, the seeminglly attractiveness of the fiscal terms in the Ammended Act, which is to expand output from investment in Nigeria deep offshore in the country is conjectural. The purpose of this paper is to evaluate the impact of the amendments to the PSC Act on value creation and addition to stake holders using systems and economic metrics that include investment earning power and discounted government take. A designed petroleum economic modeling framework applied to the fiscal terms in the new Act show a significant decrease in value addition to contractor portfolio of assets by about 25% but increases government discounted take statistics from 63.70% to 72.64% in comparison to the fiscal and contract terms in PSC 1993. The IRR and FLI obtained using the terms in the new Act were 23.66% and 0.043, respectively.
Effect of Skin Factor on a Pressure Maintenance Project
Authors: Raji Abubakar , Ogolo Oghenerume , Anochie Victor
Published: August 2020

The causes of low oil production from wells includes skin, low permeability and high rate of pressure depletion among other factors. Skin is a major challenge in oil production because it causes additional pressure drop around the wellbore. Hence, there is a drop in oil flow from the resevoir to surface facilities. Skin could be as a result of formation damage, poor production practices, well deviation, and poor well completion. The effect of skin is measured using skin factor which is a dimensionless parameter. A positive value of the skin factor indicates flow restriction while a negative value indicates a stimulated reservoir. Pressure maintenance is a method used to increase oil recovery from the reservoir by maintaining the reservoir pressure above the bubble point pressure of the reservoir. In this study, water injection was used as the method of pressure maintenance. The results showed that skin factor has much effect on oil production despite the pressure maintenance carried out in the reservoir; the rate of oil production was hindered depending on the value of the skin factor for the well. Oil reservoirs are more sensitive to skin despite pressure maintenance and in some scenario the skin even had a greater effect. Also, for wells in a reservoir having high skin factor, it is advisable to reduce the injection pressure and flowrate. The voidage replacement ratio should be recalculated to consider the outflow from the wells. The simulation resuts also showed that for reservoir with wells having high skin factor, pressure maintenance is very risky because this could lead to over pressure in the reservoir and when the reservoir pressure exceeds the fracture pressure of the reservoir rock, the reservoir fractures thus leading to loss of oil from the reservoir.
A Model for Predicting Elemental Sulphur Induced Permeability Damage in a Fractured Sour Gas Reservoir
Authors: Adeyemi Gbadegesin , Fadairo Adesina , Ogunkunle Temitope , Oladepo Adebowale , Alozie Amachree , Vamegh Rasouli , Kegang Ling , Oredeko Olugbenga
Published: August 2020

The complexity and damages that result from the precipitation and deposition of hydrogen sulfide (H2S) in the sour gas reservoirs constitute challenges during modeling of gas production and transportation from such reservoirs. During production from a fractured gas reservoir with high H2S saturation, a continuous drop in the pressure is experienced within the formation. The change in pressure generally leads to a decline in the sulphur solubility and precipitation when it reaches its critical saturation state. Sulphur deposition in the pore spaces and throats of the formation rock eventually leads to porosity and permeability damage. It becomes paramount to have a model that depicts what happens in the formation throughout the life of the reservoir and to show the damage trend of the formation as the production time increases. In this current study, Robert's Sulphur deposition model was modified to account for non-darcy flow and fracture properties in the near-wellbore region. The results show that a decrease in fracture aperture lead to a decrease in the formation permeability. It also shows that higher production rate leads to increase in rate of sulphur deposition, and conclusively fracture aperture has a severe influence on the permeability of the formation as damage done in such reservoirs due to sulphur precipitation are more severe. It is advisable to maintain pressure above the critical pressure at which sulphur precipitation is activated, in order to maximize production and not to induce additional pressure drop caused by sulphur plugging on flow conduits.
Investigating Flow Regimes in High Temperature High Pressure HPHT Gas Subsea Tieback
Authors: Maria Sheilla , Iyalla Ibiye , Okulaja Olubukola
Published: August 2020

Flow assurance is of significance importance in the oil and gas industry as the produced fluids are typically multiphase in nature. Multiphase flow is the flow of two or more phase in a conduit. The density and viscosity difference of the phases results in the phase separation and difference in pipe wall shear stresses for each phase. The most characteristic feature of multiphase flow is the flow regime (or flow pattern); which is the variation in the physical distribution of phase in the flow conduit. This work seeks to provide a better understanding of flow regimes in a long-distance high pressure and high temperature (HPHT) gas subsea tiebacks with a view to help predict and mitigate potential flow assurance issues. Computational fluid dynamics (CFD) using volume of fluid (VOF) model was used to identify flow regimes, analyse pressure drop and temperature for various gas to liquid concentrations and varying initial gas velocity for horizontal and vertical pipe. The results show elongated bubble, stratified smooth, stratified wavy, slug and dispersed bubble annular flow regimes for horizontal pipe, and elongated bubble, churn, slug and dispersed bubble annular flow regimes for vertical pipe. The ability to predict the expected flow regimes for a subsea tieback will enable the use of appropriate mitigation technique for potential flow assurance issues.
Experimental Studies on the Performance of Bio Based and Industrial Surfactants in Enhanced Oil Recovery
Authors: Abraham Damilola , Orodu Oyinkepreye , Efeovbokhan Vincent , Okoro Emmanuel , Ojo Temiloluwa , Keshinro Lekan
Published: August 2020

Surfactants are known for their unique property in lowering the interfacial tension (IFT) amid fluids injected and heavy crude oil of 22.3°API. In this present work, an original surfactant was formulated from natural oil (Castor oil) to see its use in enhanced oil recovery. The results from interfacial tension reduction by the castor oil-based surfactant were compared to that of the industrial surfactant (Methyl ester sulfonate). The IFT between the aqueous phases was measured then the effect of the surfactants was studied in core flooding experiments. The IFT was found to be reduced to as low as 12.1 mN/m using the castor-based surfactant and 12.3 mN/m using the industrial surfactant. The influence of brine concentration on IFT was also investigated. Results from core floods showed that the range of oil recovery after waterflood is in the range of 30-40% and the additional recovery from surfactant flooding in the range of 35-46%.
Using Difference Factor Thermodynamics Models in Hydrate Formation Prediction During Surface Production Well Testing
Authors: Green Igoniwari , Wami Emenike , Jimmy Dorcas
Published: August 2020

All oil fields under water-drive, including gas-cap and depletion reservoirs may produce some water along with oil. This co-production of water causes an additional set of challenges: corrosion, scale/salts deposition, disposal of the water itself, and gas-hydrate formation. Hydrates are ice-like solids that form when free water and natural gas combine at high pressure and low temperature. This can exist in gas and gas/condensate wells, as well as in oil wells. Hydrate formationis a very serious challenge and can result in a huge loss especially during production. It's also one of the major challenges encountered during surface production well testing and it is controlled by several factors which include thermodynamics and kinetics of the system. This study presents a thermodynamic model under operating field conditions, which centers on changes in the Langmuir constant of the guest molecule(s) which is an important parameter in the hydrate formation process. In this study, real-time production data acquisition system was used to acquire surface production well testing data such as pressure, temperature, and choke size, from a hydrate well. The acquired real-time data were used to determine the effect of the variation in choke size on Langmuir constant and therefore on hydrate formation. Evaluating the Langmuir constant for large cavity under field conditions using a generalized correlation, the Difference Factor method was developed and expanded to incorporate the choke sizes variation. The correlation shows that Langmuir constant (decreases) is inversely proportional to the choke size (increases) causing a decrease in the rate of hydrate formation. Due to an increase in choke size, Langmuir constant approaches zero, therefore the product of fugacity and Langmuir constant which is the driving force for hydrate formation approaches zero, leading to zero hydrate formation.
Best RM Practices for Managing Drilling Margin: A Deepwater Field Experience
Authors: Adegboye Phillip , Bodunde Williams , Mboto John
Published: August 2020

In the buildup to the drilling campaign in Agbami, the field encountered disruption in its gas injection capability due to hydrate formation in one of the gas injection manifolds. In addition to this operational challenge was a delay in the arrival of the rig. The impact of these two major issues was higher depletion in reservoir pressures in the field than originally planned, with the attendant narrow drilling margin. This narrow drilling margin posed a significant challenge to the success of the drilling campaign.

A multidisciplinary team comprising of Reservoir Engineers, Geologists, Drilling and Completion Engineers collaborated to assess the potential impact of these two issues on forthcoming drilling campaign. The team found out that the shallow reservoirs of the field were most impacted. The team then evaluated multiple options for addressing the foreseeable pressure depletion with its attendant drilling margin challenge. Leveraging the stream of downhole surveillance data from the intelligent completions in the field, reservoir simulation model was used to assess the optimal production and injection rates for the reservoirs, in addition to the priority given to the limited available gas and water for injection into the identified reservoirs that will boost pressure adequately prior to commencement of the drilling campaign. Furthermore, rig schedule optimization was carried out to align the well drill dates to those from the reservoir simulation.

This joint effort resulted in improved reservoir pressures in the shallow reservoirs that enabled safe drilling margin during the successful drilling campaign.
Maple Field Rejuvenation: A Practical and Effective Approach for Field Production Increase through Gas Lift
Authors: Kuku Abimbola , Adowei Ebikeme , Jumbo Sandison , Dada Yemi , Ajao Oyekunle , Aina Soji , Okeke Genevieve
Published: August 2020

Maple Field was discovered in 1965 and started production in 1968. Peak production was attained in 1979 but has since been declining due to various factors such as funding challenges, ageing infrastructure, pending waterflood for reservoir pressure maintenance and inadequate artificial lift sources which constitutes a significant challenge with many wells "pre-maturely" quitting production on low tubing head pressure (LTHP) as water cut increases and reservoir pressure declines. The main source of artificial lift in Maple Field and other Chevron JV Fields is "Gas Lift". The Gas Lift capability in the Maple field is essentially based on an unconventional approach of using highly pressured wells with high gas to oil ratio (GOR) to serve as "gas source" wells to gas lift producing wells that have vertical lift performance challenges. It should be noted that this methodology constitutes a "fortuitous" scenario at best given that the gas source wells were not initially planned for such purposes but were producers that experienced early gas breakthrough or gas coning and were later converted to "gas source" wells. This has proven to be a workable solution but inadequate in meeting the overall gas lift demand for the Field largely due to the limited number of highly pressured/ high GOR wells and the usually low volume of gas that they produce. Other challenges to this system include the hydrated nature of the gas injected as the injected gas is essentially untreated off water and tend to reduce the gas lift efficiency. The alternative option of installing a conventional gas lift network system with associated surface equipment such as compressors and dehydration units has proven to be economically challenged due to the huge investment required for the installation and running of such systems when compared to the expected "prize" of marginal reserves development from a matured asset as the Maple Field. These issues provided both a challenge and an opportunity for the Maple Field project team consisting of both subsurface & facilities engineers to come up with cost effective and pragmatic solutions that is geared towards providing a more sustainable and adequate gas supply for the Field for gas lifting purposes. These efforts resulted in the production increase of ~ 2,000 BOPD in the Field.
Agbami Next Generation Frac Pack Equipment Development & Deployment
Authors: Adegbulugbe Kayode , Elendu Chidi , Ugah Ibrahim , Ojukwu Ihechi
Published: August 2020

Agbami producer wells are mostly installed with stacked Frac Pack completions9,10,11 with IWC capability to adequately control and monitor production intervals. The first completions were installed in 2007, while production commenced in 20081,2. By 2015, when Agbami phase 3 completions were being installed, the reservoirs had been significantly depleted and the wells were more directionally complex thus leading to a relatively more challenging completions design and execution. The depletion led to severe post-frac fluid losses with attendant significant time required to cure such losses often by pumping LCMs which further impacts the well productivity. There were also substantial operational challenges in locating tool positions and activating the ball check (RABC) which worsened due to the more directionally challenging profile.

However, there has not been a major change in the Agbami completion equipment and service tools to manage these challenges since the first completions were installed. Significant completion installation Non-Productive times were incurred during the phase 3 completions installations which are directly attributable to these challenges.

The Agbami drilling team and service providers identified and successfully implemented opportunities to upgrade the Agbami frac pack service tools to mitigate against the frac pack execution challenges. These upgrades effectively addressed the challenges of the older generation service tool configuration and resulted in much improved completion execution and post-completion productivity for the AIDP wells.
Comparative Analysis of Local and Conventional EOR Agents
Authors: Uzoho Chidinma Uzoamaka , Onyekonwu Mike Obi , Akaranta Onyewuchi
Published: August 2020

Latest research in Nigeria, West Africa had shown the possibility of sourcing for low cost chemicals for enhancing oil recovery. In this work, a comparative study was done using local and conventional chemicals for Core Flooding experiment under same conditions. These chemicals are NaOH, KOH, Na2CO3, Polyacrylamide, Sodium Dodecyl Sulphate and Akanwu, Palm Bunch Ash, Plantain Peel Ash, Xero-Detergent, Okro as conventional and local EOR agents respectively. The results showed that local chemicals performed as good as the conventional chemical giving an additional recovery of 11.54%, 21.43%, 17.86%, 12.73%, 17.39% and 17.25%, 12.50%, 9.60%, 20.69%, 18.70% for conventional and local EOR agents respectively. These local materials were characterized using EDXRF and its results verified that the local materials actually contained some chemical components responsible for their performance. The significance of this research work is economic boom to the oil and gas industries, job creation, and increase in the Nation's GDP.
Assessment of Natural Gas Infrastructure Development in Ghana
Authors: Yaw Boahen Kenneth , Oppong Riverson
Published: August 2020

Natural Gas Infrastructure is an integral component of our economic and societal development. This in recent times, has drawn global investments and continues to be a major backbone to the world energy mix. Analysis of the data shows a financial and knowledge gap in the development of gas infrastructures in Ghana. In addition, there is limited private sector participation in gas infrastructure development due to a government policy framework. Further assessment shows that natural gas was mainly being used for power generation, industrial heating applications with Liquefied Petroleum Gas as its by-product used for domestic cooking.

In conclusion, a gas infrastructural development fund needs to be established to support activities within the sector for the full realization of the Gas Master Plan. Also, human resources training within the various technical universities on natural gas development must be enhanced. There is a need for a review of the policy framework to factor in private sector participation through public-private partnership in gas infrastructure development as well as improvement in fiscal regime to mitigate risk and create a friendly environment for investors. The study unearthed other economic benefits that could fully be utilized for the economic and sustainability of society. In agriculture, it was realized that natural gas can be used for making protein-rich animal feed and also in fertilizer for crop production. In transportation, compressed natural gas can be fully utilized as fuel for vehicles resulting in reduced emissions to the environment. Natural gas could also play a key role in cement manufacturing, methanol production, fabrics, and paint manufacturing.
Optimizing Production in a Brown Field Through Innovative Inter Well Gaslift Initiation – Field XK Success Story
Authors: Imoukhuede Peter , Okeahialam Anselm , Anyanwu Emeka , Ekeng Oyie
Published: August 2020

The XK field is a mature offshore asset with post peak production characterized by rapid oil decline rate and steep water cut. Many wells have ceased flow prematurely over time and non-rig interventions to reactivate and restore the wells to production had typically been ineffective owing to consistent low tubing head pressures and well construction/completions. Furthermore, the plan to initiate gaslift operations in the field was challenged by the lack of gaslift separator, compressor unit and gas line coupled with the fact that many of the wells were completed without gaslift mandrels. The deployment of innovative inter well gaslift, utilizing Gas Liquid Cylindrical Cyclone (GLCC) separator saved the situation and enabled achievement of the gaslift objective. The result was the successful restoration of three (3) long shut-in wells and associated increased oil production in the field.

This paper discusses the opportunities and challenges from inter well gaslift initiation and operations in XK field and the enormous potential as a low cost and efficient system for rejuvenating Brown Fields.
The Impact of Frailty on Admission to Home Care Services and Nursing Homes: Eight-Year Follow-Up of a Community-Dwelling, Older Adult, Spanish Cohort
Authors: Cegri Francisco , Orfila Francesc , Abellana Rosa M , Pastor-Valero María
Published: August 2020

BackgroundFrailty in older adults is a common multidimensional clinical entity, a state of vulnerability to stressors that increases the risk of adverse outcomes such as functional decline, institutionalization or death. The aim of this study is to identify the factors that anticipate the future inclusion of community-dwelling individuals aged ≥70 years in home care programmes (HC) and nursing homes (NH), and to develop the corresponding prediction models. MethodsA prospective cohort study was conducted in 23 primary healthcare centers located in Catalonia, Spain, with an eight-year follow-up (2005-2013). The cohort was made up of 616 individuals. Data collection included a baseline multidimensional assessment carried out by primary health care professionals. Outcome variables were collected during follow-up by consulting electronic healthcare records, and the Central Registry of Catalonia for mortality. A prognostic index for a HC and NH at eight years was estimated for each patient. Death prior to these events was considered a competing risk event, and Fine–Gray regression models were used. Results At baseline, mean age was 76.4 years and 55.5% were women. During follow-up, 19.2% entered a HC program, 8.2% a NH, and 15.4% died without presenting an event. Of those who entered a NH, 31.5% had previously been in a HC program. Multivariate models for a HC and NH showed that the risk of a HC entry was associated with older age, dependence on the Instrumental Activities of Daily Living, and slow gait measured by Timed-up-and-go test. An increased risk of being admitted to a NH was associated with older age, dependence on the Instrumental Activities of Daily Living, number of prescriptions, and the presence of social risk.ConclusionsPrognostic models based on comprehensive geriatric assessments can predict the need for the commencement of HC and NH admission in community-dwelling older adults. Our findings underline the necessity to measure functional capacity, mobility, number of prescriptions, and social aspects of older adults in primary healthcare centers. In such a setting they can be offered longitudinal holistic assessments so as to benefit from preventive actions in order to remain independent in the community for as long as possible.
Association between multi-component initiatives and physical activity-related behaviors: interim findings from the Healthy Schools Healthy Communities Initiative
Authors: Calise Tamara , Spitzer Natalie , Ruggiero Laura , Ryder Amanda , Wingerter Chloe , Hatcher Ashley
Published: August 2020

Background: Little is known about the intensity of multi-component initiatives (MCI) inclusive of any combination of programs, practices, policies, and environmental changes (P3E) on youth behaviors. Methods: The Healthy Schools Healthy Communities (HSHC) initiative worked to increase access to PA opportunities as part of 33 MCIs targeting school districts and respective communities. The purpose of this study was to assess whether MCIs with higher scoring PA-related strategies were associated with improved PA and sedentary behaviors among youth. PA-related interventions were assigned point values based on three characteristics: 1) purpose of initiative); 2) duration; and 3) reach. An overall composite score of all activities was calculated for each school district. Multivariate longitudinal regressions were applied, controlling for measurement period, Cohort, and district enrollment. Results: P3E scores ranged from 0.3 to 3.0 with 20% considered “higher-scoring” (score > 2.1) and 47% considered “lower-scoring” ( < 1.2 ). Average composite district P3E scores more than tripled over the evaluation period, rising from 14.8 in the first grant year to 32.1 in year 2, 41.1 in year 3, and 48.1 in year 4. For each additional point increase in average composite district P3E intensity score, the number of days per week that students reported being physically active for at least 60 minutes increased by 0.010 (p<0.01). For each additional point increase in district P3E intensity score, the number of hours per weekday that students reported engaging in screen time activities decreased by 0.006 hours (p<0.5). Conclusions: MCIs are difficult to evaluate given the variations within which they are implemented. Findings from this study suggest the value of a systematic scoring approach in assessing MCIs. In addition to tracking intensity over time, scoring can provide justification for, or against, an individual activity and ways to increase the likelihood of the MCI impacting population-health outcomes.
Reablement through time and space: A scoping review of how the concept of ‘reablement’ for older people has been defined and operationalised
Authors: Clotworthy Amy , Kusumastuti Sasmita , Westendorp Rudi GJ
Published: August 2020

Background : While the field of rehabilitation has determined a common definition of professional practice, legislators and healthcare professionals in various Western countries have struggled to reach consensus about how the newer offer of ‘reablement’ should be organised, operationalised, and understood as a health service for older adults. International research indicates that there is confusion, ambiguity, and disagreement about the terminology and the structure of these programmes, and they may not be adequately supporting older people’s self-identified goals. Could an analysis of the concept’s genealogy illuminate how reablement can be more effective and beneficial in theory and in practice?
Methods : We conducted a qualitative and quantitative scoping review to determine how reablement has developed through time and space. Eligible articles ( n=86 ) had to focus on any of the defined features of current reablement programmes; there were no restrictions on study designs or publication dates. In articles published from 1947–2019, we identified themes and patterns, commonalities, and differences in how various countries described and defined reablement. We also performed an analysis using computer software to construct and visualise term maps based on significant words extracted from the article abstracts.
Results : The fundamental principles of reablement have a long history. However, these programmes have undergone a widespread expansion since the mid-2000s with an intention to reduce costs related to providing long-term care services and in-home assistance to growing older populations. Despite theoretical aspirations to offer person-centred and goal-directed reablement, very few countries have been able to implement programmes that adequately promote older people’s goals, social involvement, or participation in their local community in a safe, culturally sensitive and adaptable way.
Conclusions : Reablement is meant to support older people in attaining their self-defined goals to be both more physically independent at home and socially involved in their communities. However, until legislators, health professionals, and older people can collectively reach consensus about how person-centred reablement can be more effectively implemented and supported in professional homecare practice, it will be difficult to determine a conceptual description of reablement as a service that is unique, separate, and distinct from standard rehabilitation.
Dolphinfish Movements in the Eastern Pacific Ocean of Mexico Using Conventional and Electronic Tags
Authors: Perle Christopher R. , Snyder Stephanie , Merten Wessley , Simmons Melinda , Dacey Justina , Rodriguez-Sanchez Ruben , O’Sullivan John , Ortega-Garcia Sofia
Published: August 2020

Background The dolphinfish, Coryphaena hippurus , is a fast-swimming, predatory fish exhibiting relatively fast growth and early maturation among marine teleosts. It is an important, potentially renewable resource throughout its global subtropical-to-tropical range. Understanding the ecology of this wide-ranging fish is critical to proper fisheries management, but studies have historically depended heavily upon aggregated catch data reported by fisheries. This study uses tagging data to explore finer scale dolphinfish movements in two subregions of the Eastern Pacific Ocean (EPO) – the west coasts of Baja California Peninsula (WBC) and Oaxaca (OAX), Mexico. Results Adult dolphinfish (fork length 66 cm - 129 cm) were tagged with conventional (n = 132 tags) and electronic tags (n = 30 tags, miniPAT) between 2010 and 2014. Recapture rate of conventional tags was 4.5% with a maximum days of liberty of 141 days (mean = 56 d); twenty electronic tags reported but all did so prior to programmed release dates, with days at liberty ranging from 4 to 62 (mean = 24 d). Fish remained within the region they were tagged except for six fish tagged in WBC and one in OAX. Latitudinal (WBC) and longitudinal (OAX) extensions of observed fish movements (determined via a novel analytical approach) increased with days at liberty. Despite occasional deep dives (max 262 m), fish remained surface oriented with short excursions below the isothermal layer but larger OAX fish (fork length [103 cm, 120 cm]) inhabiting warmer waters (sea surface temperatures (SST) > ~26 °C) spent more time below the isothermal layer than smaller fish (fork length [90 cm,112 cm]) inhabiting colder WBC surface waters (SST > ~22 °C).Conclusions This study reveals movements of dolphinfish that infer regional differences in thermal habitat utilization and displacement over time. This inference evokes questions important to fisheries management regarding the three-dimensional extent of the dolphinfish’s realized thermal niche, its population structure, and the spatiotemporal connectivity of its habitats within the multinational EPO. With improved tag retention, longer deployments should capture increasing displacements along observed axes (N/S vs. E/W); the orientation of seasonal displacement axes suggest longer-distance movements would provide opportunities for reproductive mixing via trans-national migrations.
Demonstrating the presence of Ehrlichia canis DNA from different tissues of dogs with negative PCR in blood
Authors: Rodríguez-Alarcón Carlos Arturo , Beristain-Ruiz Diana M. , Olivares-Muñoz Angélica , Quezada-Casasola Andrés , Pérez-Casio Federico , Álvarez-Martínez Jesús A. , Tapia-Alanís Jane , Lira-Amaya José J. , Rivera-Barreno Ramón , Cera-Hurtado Orlando S. , Ibancovichi-Camarillo José A. , Soon-Gómez Luis , Adame-Gallegos Jaime Raul , Figueroa-Millán Julio V.
Published: August 2020

Background: Nowadays, Ehrlichia canis receives increasing attention because of its great morbidity and mortality in animals. Dogs in the subclinical and chronic phases can be asymptomatic, and serologic tests show cross-reactivity and fail to differentiate between current and past infections. Moreover, there could be low parasitaemia, and E. canis might be found only in target organs, hence causing results to be negative by polymerase chain reaction (PCR) on blood samples.Methods: We evaluated by PCR the prevalence of E. canis in blood, liver, spleen, lymph node and bone marrow of 59 recently euthanised dogs that had ticks but were clinically healthy.Results: In total, 52.55% of the blood PCRs for E. canis were negative, yet 61.30% yielded positive results from tissue biopsies and were as follows: 63.15% from bone marrow, 52.63% from liver, 47.36% from spleen and 15.78% from lymph node. In addition, 33% had infection in three tissues (spleen, liver and bone marrow).Conclusions: Our results show the prevalence of E. canis from tissues of dogs that were negative by blood PCR. E. canis DNA in tissue was 30% lower in dogs that tested negative in PCR of blood samples compared to those that were positive. However, it must be taken into account that some dogs with negative results were positive for E. canis in other tissues.