bluuebunny/crossref_metadata_2025 huggingface dataset:
Meningkatan Hasil Belajar Siswa Menggunakan Realistic Mathematics Education (RME) Berbantuan Media Konkrit
Authors: Setyawan Dedy
Published: August 2020

Abtract. This study aims to improve the activity and student learning outcomes in mathematics in calculating the volume of a cube by using the Realistic Mathematics Education (RME) model assisted by concrete media.This type of research is Classroom Action Research (CAR). The subjects of this study were 5th  grade students of Muhammadiyah Pahandut Palangka Raya Elementary School, totaling 19 people. The sampling technique used is saturated sampling. Data collection techniques using observation and tests.The main results of this study indicate that the learning activities of students when learning mathematics material calculates the volume of the cube using the RME model assisted by concrete media shows the final test results of cycle 1 with 73.68% and the final test results in cycle 2 to 100% and are in very good criteria. It is proven that by using the RME model which is assisted by concrete media can increase student mathematics learning activities and outcomes.

Abstrak. Penelitian ini bertujuan untuk meningkatkan aktivitas dan hasil belajar matematika siswa dalam menghitung volume kubus dengan menggunakan model Realistic Mathematics Education (RME) berbantuan media konkret. Jenis penelitian yang digunakan adalah Penelitian Tindakan Kelas (PTK). Subjek penelitian ini adalah siswa kelas V SDS Muhammadiyah Pahandut Palangka Raya yang berjumlah 19 orang. Teknik pengambilan sampel yang digunakan adalah sampling jenuh. Teknik pengumpulan data menggunakan observasi dan tes.  Hasil utama penelitian ini menunjukan bahwa Aktivitas belajar siswa pada saat pembelajaran Matematika materi menghitung volume kubus dengan menggunakan model Realistic Mathematics Education (RME) berbantuan media konkret di kelas V SDS Muhammadiyah Pahandut Palangka Raya menunjukkan hasil tes akhir siklus 1 dengan 73,68% dan hasil tes akhir pada siklus 2 menjadi 100% dan berada pada kriteria sangat baik. Terbukti bahwa dengan menggunakan model Realistic Mathematics Education (RME) berbantuan media konkrit dapat meningkatkan aktivitas dan hasil belajar matematika siswa.
Types and Characteristics of Kyai Leadership Within Pesantren
Authors: Muttaqin Imron
Published: August 2020

This article attempts to explore types and characteristics of Kyai leadership within Pesantren. This library research found that there are 412 articles related to the leadership of Kyai. Based on the inclusion criteria, there are 12 articles yielded as the material sources. The appropriate data found in the searching machine is analyzed accordingly to the research questions by employing a qualitative approach. Specifically, the types of Kyai leadership within Pesantren are charismatic, transformative, and democratic leaderships. The characteristics of Kyai leadership in Pesantren including having a strong and authoritative leadership character in maintaining Pesantren’s education and development; keeping the traditions, local principles and interacting with global values; having internal and external networks e.g a genealogical, ideological, historical, intellectual, theological, and spiritual networks in serving Islam and Indonesia. This research recommends for further researchers to address this study focuses on a networking of Kyai. The themes of Kyai’s intellectual networks, ideological networks, spiritual networks, theological network are highly recommended.
Syndepositional tectonics and mass-transport deposits control channelized, bathymetrically complex deep-water systems (Aínsa depocenter, Spain)
Authors: Tek Daniel E. , Poyatos-Moré Miquel , Patacci Marco , McArthur Adam D. , Colombera Luca , Cullen Timothy M. , McCaffrey William D.
Published: August 2020

The inception and evolution of channels in deep-water systems is controlled by the axial gradient and lateral confinement experienced by their formative flows. These parameters are often shaped by the action of tectonic structures and/or the emplacement of mass-transport deposits (MTDs). The Arro turbidite system (Aínsa depocenter, Spanish Pyrenees) is an ancient example of a deep-water channelized system from a bathymetrically complex basin, deposited in an active tectonic setting. Sedimentologic fieldwork and geologic mapping of the Arro system has been undertaken to provide context for a detailed study of three of the best-exposed outcrops: Sierra de Soto Gully, Barranco de la Caxigosa, and Muro de Bellos. These locations exemplify the role of confinement in controlling the facies and architecture in the system. Sedimentologic characterization of the deposits has allowed the identification of fifteen facies and eight facies associations; these form a continuum and are non-unique to any depositional environment. However, architectural characterization allowed the grouping of facies associations into four depositional elements: i) weakly confined, increasing-to-decreasing energy deposits; ii) progradational, weakly confined to overbank deposits; iii) alternations of MTDs and turbidites; iv) channel fills. Different styles of channel architecture are observed. In Barranco de la Caxigosa, a master surface which was cut and subsequently filled hosts three channel stories with erosional bases; channelization was enhanced by quasi-instantaneous imposition of lateral confinement by the emplacement of MTDs. In Muro de Bellos, the inception of partially levee-confined channel stories was enhanced by progressive narrowing of the depositional fairway by tectonic structures, which also controlled their migration. Results of this study suggest that deep-water channelization in active tectonic settings may be enhanced or hindered due to: 1) flow interaction with MTD-margin topography or; 2) MTD-top topography; 3) differential compaction of MTDs and/or sediment being loaded into MTDs; 4) formation of megascours by erosive MTDs; 5) basin-floor topography being reset by MTDs. Therefore, the Arro system can be used as an analog for ancient subsurface or outcrop of channelized deposits in bathymetrically complex basins, or as an ancient record of deposits left by flow types observed in modern confined systems.
The Effect of Model Error Identification on the Fast Reservoir Simulation by Capacitance-Resistance Model
Authors: Mamghaderi Azadeh , Aminshahidy Babak , Bazargan Hamid
Published: August 2020

Using fast and reliable proxies instead of sophisticated and time-consuming reservoir simulators is of great importance in reservoir management. The capacitance-resistance model (CRM) as a fast proxy has been widely used in this area. However, the inadequacy of this proxy for simplifying complex reservoirs with a limited number of parameters has not been addressed appropriately in related works in the literature. In this study, potential uncertainties in the modeling of the waterflooding process in the reservoir by the producer-based version of CRM (CRMP) are formulated, leading to embedding a new error-related term into the original formulation of the proxy. Considering a general form of the model error to represent both white and colored noises, a system of a CRMP-error equation is introduced analytically to deal with any type of intrinsic model imperfection. Two approaches are developed for the problem solution including the following: tuning the additional error-related parameters as a complementary stage of a classical history-matching procedure, and updating these parameters simultaneously with the original model parameters in a data-assimilation approach over model training time. To validate the model and show the effectiveness of both solution schemes, the injection and production data of a water-injection procedure in a three-layered reservoir model are used. Results show that the error-related parameters can be matched successfully along with the model original variables either in a routine model calibration procedure or in a data-assimilation approach by using the ensemble-based Kalman filter (EnKF) method. Comparing the average of the obtained range for the liquid rate as the problem output with true data demonstrates the effectiveness of considering model error. This leads to substantial improvement of the results compared with the case of applying the original model without considering the error term.
Lessons Learned from Drilling a Long Open Hole Interval and Recovery from a Stuck Pipe Incident
Authors: Akinfolarin Ayodele , Amah Obinna , Ijeh Isijokelu , Djauro Chiwar , Omoregie Samson , Usim Mike , Tien Willhelm , Emesi John , Mordi Joseph
Published: August 2020

Drilling long open hole sections has been known to result in many challenges including wellbore instability problems which may lead to stuck pipe problems. However, well design or operational challenges may necessitate making such risky decisions. In such situations, precautionary measures will need to be taken to ensure that the hole is successfully drilledwith minimum to no wellbore instability problems which have negative impact on time and cost.

The case study, well FX-3 is a well drilled by one of the major oil and gas companies in the Niger Delta. The tophole was planned to be drilled in two sections: a pilot hole to the planned section total depth and then with a hole opener to open the pilot hole to the required hole size. Due to the abrasive formation type and difficulties encountered while drilling to the planned depth, decision was made to set the casing shallower than planned. This necessitated drilling the 12-1/4" hole section longer than planned. With this decision, several challenges were encountered and eventually overcome. The well was successfully completed.

The objective of this paper is to present the lessons learned in drilling a long open hole interval and the recovery operations from a stuck pipe incident within that interval in the well. It discusses both the well design and actual field practices, with significant emphasis in the recovery operations from the stuck pipe incident. One of the key events is the spotting of special pipe freeing pills, which in combination of other activities led to the freeing of the stuck bottom hole assembly which had a radioactive source. Some of the key learnings are the need to optimise the well design, proper hole cleaning and mud conditioning prior to drilling to section total depth. The knowledge of the pipe sticking mechanism and the application of the right pipe freeing formulations are important considerations in freeing any stuck pipe
Managing Asset Retirement Obligation of Nigerian Oil Companies: The Elephant in the Room
Authors: Ojukwu Kelechi Isaac
Published: August 2020

Asset retirement obligation (ARO) will play a vital role in the valuation of Nigerian petroleum assets, and most importantly, in providing analysts and operators with a regulatory mechanism with which to assess the ultimate value of an asset. It can also form the basis for holding the licensees accountable for their contractual obligations on environmental issues and the legislation governing field abandonment and reclamation liabilities at the end of the useful (economic) life of a project. Viewed as the potential elephant in the room, this lifecycle environmental liability can sometimes exceed terminal asset value, unless it is carefully managed by both the company and the regulator. The fact that there is no active regulatory framework currently in existence in Nigeria underscores the urgency for a system to guide oil companies in accrual and compliance obligations. Absence of such system can have significant but latent impact on what the future value can be as well as the exit or terminal liabilities. As crucial as ARO seems to be, experts believe that Nigeria's ARO liability coming from well abandonments, facility decommissioning and site reclamations may exceed $9 Billion, if properly assessed.

Establishing the ARO liability of Nigerian oil companies is one tool that the regulator needs to effectively manage accrual, amortization and contributions. It will help to enforce compliance with the laws as well as bind the licensees to their contractual obligation to Nigerian government and various lenders. To determine ARO, certain legislative, financial, technical, economic, environmental and commercial criteria must be considered in the estimation and assignment of liability. The paper aims to review existing regulatory regimes and leverage that to proffer new ways by which the government and its stakeholders can harness the best technical, financial and operational practices to improve the situation and reposition the industry going forward into the future.

This paper therefore addresses the key issues starting from ARO estimation, when does it accrue and who should implement it. It deals with fiscal or financial reliefs based on global best practices and proposes win-win schemes for Nigeria's government and operators. Implementing ARO will safeguard Nigeria's long-term economic and environmental interests, and consequently, become the cornerstone upon which an abandonment blueprint can be proactive and retroactive implemented.
Production Improvement Through Wax Management Strategy in Offshore Niger Delta Field, Nigeria
Authors: Uche Chukwunonso , Eremiokhale Obehi , Uche Jennifer , Kuku Olatunde , Sanusi Sherif , Omisore Adenike
Published: August 2020

Wax precipitation along oil well tubing causes deferment in production while being produced from the formation through production facilities. Existing formulations for inhibiting wax formation include, chemical injection at different dosages and depths, mechanical inhibiting forms and thermal methods used in overcoming wax formation temperature. A well in one of the Niger Delta offshore field suffered down hole wax deposition after each field shut down. A triplex pump which serves six fields was used to provide a remedial solution after an average well downtime of seven days. In order to control this challenge, crude oil pour point was determined from historical production and temperature profiles and a hot reservoir fluid circulation strategy was developed with the objective of optimizing production through reduced well downtime and minimized expenditures. The technique used shall be discussed in this work. This formulated strategy saved over a five million US dollar per annum.
An Innovative Approach to Brown Field Reservoir Management in Marginal Field Operation
Authors: Uche Chukwunonso , Eremiokhale Obehi , Omisore Adenike , Bukar Ibrahim , Uche Jennifer , Blankson Eyituoyo , Hamzat Ayomide
Published: August 2020

A major cause of increase in the number of well abandonments in small heterogenous formations with high geological complexities is early water breakthrough into completions which leaves pockets of bypassed oil that ultimately affects the overall recovery from such formations. This paper highlights some reservoir management strategies adopted to improve reserves from a Niger Delta formation with an API of 22 Deg. Reservoir management strategies adopted included the use of down hole gauges, inflow control devices, and detailed production/injection surveillance. Updated 3D simulation model and material balance analysis were also used for evaluation of waterflood recovery efficiency and real time Reservoir management decisions. Other Reservoir management practice helped in stimulating gas cap expansion that increased daily oil rate from this reservoir and field gas rate that helped in gas lifting wells in other heavy oil reservoirs with high BSW.
A Comparative Evaluation of Selected Correlations for Estimating Wax-Appearance Temperature of Crude Oils
Authors: Eyitayo Stella I. , Lawal Kazeem A. , Guobadia Kenneth O. , Ovuru Mathilda I. , Okoh Oluchukwu M. , Yadua Asekhame U. , Matemilola Saka
Published: August 2020

From a precipitation standpoint, wax is one of the most vulnerable hydrocarbon contents of crude oil and gas condensate. As a result, wax appearance temperature (WAT) is an important consideration for the management of flow-assurance challenges in the oil and gas industry. Ideally, the determination of WAT requires laboratory analysis of representative fluid samples. In the alternative, rigorous thermodynamic models are employed. However, both the laboratory and rigorous thermodynamic methods are expensive and demanding, yet they do not always guarantee accurate results for the full range of expected operating conditions. Either as a complement or substitute to these rigorous methods, several empirical correlations are available for predicting WAT. Two of these correlations are the composition-based models recently published by Hosseinipour et al. (2019).

This paper reviews and interrogates the predictive capability of the two semi-empirical WAT models developed by Hosseinipour et al. (2019). In addition, based on some experimental datasets, a new correlation is proposed, which describes WAT as a simple function of solution gas-oil ratio (GOR). Using some WAT data obtained from different crude-oil samples in the Niger Delta, robustness of the Hosseinipour et al. (2019) and the new GOR-based correlations is examined. Compared to the experimental cases used in this study, the two Hosseinipour et al. (2019) correlations returned average absolute deviation (AAD) values of 13.0 and 3.0%. Conversely, the proposed GOR-based correlation yields an AAD of 1.0%. For the samples considered in this study, in addition to its relative simplicity, the new GOR-based semi-empirical model exhibits superior performance to both correlations from Hosseinipour et al. (2019). These results notwithstanding, potential improvement areas are highlighted for the three WAT models considered. Accordingly, an augmented form of one of the original Hosseinipour et al. (2019) models is proposed and validated.
Crude Fractionating Column Hydraulic Study with Feedstock Variation using Column Analysis Tool
Authors: Ndunagu Paschal Uzoma , Alaike Emeka Emmanuel , Joel Ogbonna Friday , Oji Akuma , Megueptchie Theophile
Published: August 2020

A hydraulic scenario was created for a 125,000 BPSD Crude Distillation Unit (CDU) by blending varying ratios of two crudes; A (33.62 API) and B (25.77 API) while investigating the product yield. The product specifications were implemented using the ASTM D86 95% volume cut point. The maximum allowable blend ratio of A and B for which the CDU process simulation converged was 78/22 vol%. Under this condition, the top and bottom section experienced weeping & weir overloading respectively while maintaining process conditions. To improve column performance, top pump around flowrate was decreased by 25% to mitigate weeping while the furnace outlet temperature was increased from 367.4° C to 370° C to decrease weir loading. This paper shows that refiners can meet the increased demand for heavy ends while keeping naphtha within limits to meet demand in downstream units. Existing columns can also utilize the Aspen Hysys Hydraulic tool for troubleshooting and plant optimization.
A Holistic Approach to Injectivity Decline
Authors: Harper Christopher , Michael Nnochiri , Yan Zheng , Victor Okowi , Bamisebi Adetloye
Published: August 2020

Key criteria such as initial skin, permeability, scaling, water quality and temperature are the typical considerations employed by most injectivity or formation damage investigations, however it is our belief that this is simply not enough.

Other mechanisms and their combined or secondary effects are typically underestimated, which leads in many cases to the application of mitigation and remediation techniques, which, although initially effective, are short lived due to an inadequate understanding of the formation damage/well communication impairment mechanisms present.

The cause(s) of injectivity decline may be numerous; and are frequently interlinked. This paper examines the considerations of a holistic workflow for defining the potential cause(s) of injectivity decline. Standard considerations of the workflow include physical and chemical water treatment process, water quality and its degradation between process and sand face, flow assurance, physical and chemical interactions with the sandface and near wellbore, mineralogical interactions, microbiological influences and completion architecture.

Such approaches have found value in defining potential causes of injectivity decline, and appropriate remediations or mitigations throughout Sub-Saharan Africa, and Europe.
Effect of Amine Structure on the Corrosivity of a Carbon Steel Natural Gas Processing Plant
Authors: Narku-Tetteh Jessica , Muchan Pailin M , Supap Teeradet , Idem Raphael
Published: August 2020

This work investigated and correlated the corrosiveness of different amines with their uniquely inherent structural characteristics, specifically focusing on the effect of alkyl chain lengths of alkanolamines and diamines, and the effect of the number of -OH groups in sterically-hindered amines. The amines studied were: monoethanolamine (MEA), methylmonoethanolamine (MMEA), ethylmonoethanolamine (EMEA) and butylmonoethanolamine (BMEA) for the effect of the alkyl chain length of the alkyl group attached to the amino group of alkanolamines, and ethylenediamine (EDA), trimethylenediamine (TMDA) and hexamethylenediamine (HMDA) for the effect of alkyl chain length in diamines. For–OH effect, the amines used were: 2-amino-2-methyl-1-propanol (AMP), 2-amino-2-ethyl-1,3-propanediol (AEPD) and 2-Amino-2-(hydroxymethyl)-1,3-propanediol (AHMPD). The results showed that corrosion rates reduced as the alkyl length increased as shown in MEA > MMEA > EMEA > BMEA. For diamines, corrosion rates also reduced as the alkyl length in between amino groups increased as iluustrated in EDA >TMDA > HMDA. These were due to increased hydrophobicity which repelled water molecules more effectively from the metal surface, thereby protecting it from molecules that can cause corrosion. For–OH, the corrosion rate reduced as the number of–OH increased as in AMP>AEPD>AHMPD. In this case, the O atom, an active adsorption site that chemically adsorbs onto the metal surface, reduces the open metal surface thereby inhibiting corrosion. The results show that amines with longer alkyl length and/or higher number of–OH group will reduce corrosion rates in gas processing plants. This information will assist designers in the selection of the appropriate amines or amine blends for use in natural gas processing plants which will minimize corrosion.
Experimental Investigation on Effects of Biologically Based Corrosion Inhibitors on Flowline Material
Authors: Udoh Tinuola H. , Sunday Michael U.
Published: August 2020

In this paper, the potential of azadirachta indica and enzyme as corrosion inhibitors on mild steel was investigated. Effect of salinity, different concentrations of these corrosion inhibitors and their corrosion rate control were measured based on weight loss method over a period of 576 days. The results show that the rate of corrosion of mild steel does not change significantly after 400 days of continuous exposure to fluids. Also, a linear decrease in corrosion rate was observed with increase in azadirachta indica concentration while, increase in enzyme concentration makes no significant changes in corrosion rate beyond the initially reduced rate. Finally, the results show that corrosion inhibition capacity of azadirachta indica was only enhanced at high concentration of 10 wt.% while enzyme generated high corrosion control at all investigated concentrations except at high concentration of 10 wt.%. This study presents novel potential of biological based corrosion inhibitors application to flowline.
Optimization of Intermittent Gas Lift Surface Injection Pressure in High Water Cut Oil Well
Authors: Abdullahi Mohammed Bashir , Abdulkadir Usman , Aliyu Ahmad Musa , Shehu Bashir Umar
Published: August 2020

Gas lifted oil wells contributed substantially worldwide during the production life of the oil reservoir. The intermittent gas lift optimization process leads to an overall reduction of OPEX and increases the NPV from the asset. When the reservoir pressure is insufficient to produce the desired rate, consequently the oil well productivity declines and the percentage of water cut increases. The well level optimization is one of the practical strategies employs to optimize well parameters especially surface injection pressure of intermittent gas lift. A sensitivity study was implemented on surface injection pressure using IPM Prosper. Gas lifted oil rates were analyzed at several surface injection pressures from 1000-5400psi. The optimum surface injection pressure of 1300psi at an oil rate of 140 STB/day was achieved with 6 injection valves (4 operating valves and 2 safety valves) at a depth of total valves of 7316ft producing 80% water cut.
Optimized Production of Bioremediation Agent for Application in the Eco-Recovery of Oil Spill Site
Authors: Agbaji Joseph Egwoyi , Nwaichi Eucharia Oluchi , Abu Gideon Orkwagh
Published: August 2020

This study investigates the application of an optimization process in the formulation of a bioremediation agent modelled to mimics bioaugmentation and biostimulation and that offers a short half-life high degradation efficiency less intrusive and benign to petroleum spill-threatened biodiversity. Several optimized methods and processes were followed to harness the plethora of rhizobacterial isolates from aged oil contaminates sites, screening, and selection of isolates with potential for hydrocarbon degradation based on their specific enzymes activity and catabolic gene assay. One Variable At a Time (OVAT) is applied to screen and select the best agrowaste materials with limiting organic nutrients to support high throughput rhizobacterial isolates cultivation and for which the isolates showed a high substrate utilization affinity. The Monod model was used to establish the optimum organic nutrient capacity as estimated from their agrowaste materials proximate assay. These led to the selection of four rhizobacterial isolates and three agrowaste materials that constitutes the independent factors in the enhancement of petroleum hydrocarbon removal from contaminated soil. To further optimize this process, a multivariate statistical technique of the Box-Behnken method of 15 runs design having the independent variables of bacterial consortia (Pseudomonas fluorescens, Achromobacter agilis, Bacillus thuringiensis, and Staphylococcus lentus) of 5 to 7% inocula size, nitrogen nutrient (corn steep liquor) of 0.331 to 0.662 mgkg-1 and phosphorus nutrient (poultry droppings) 39.4 to 197.4 mgkg-1 was adopted and the model resulted in the randomization of nutrients and consortia in ratios designed to formulate a bioremediation agent. To this composition, a rich potassium source (plantain peels char) of 22.0 mgkg-1 was added. A bioremediation application study was set-up to follow the Box-Behnken modelled results and was monitored for 56d with initial Total Petroleum Hydrocarbon (TPH) content of 9744 mgkg-1 and Total Hydrocarbon Content (THC) of 964 mgkg-1. The model response from the treated sample shows a half-life of 6d, with degradation efficiency of 89.6% and 88.7% for TPH and THC removal after 21d of the study. This study established the feasibility of the application of an optimization model in the development of an efficient bioremediation agent suitable for the eco-recovery of oil spill sites.
Unlocking Potential in Mature Brown Field with Complex Configuration in the Niger Delta- The OML26 Success Story
Authors: Ageh Ebenezer , Isiba Ezinwanneakolam , Okoruwa Immaculate , Ajao Wale , Yebusika Idalla , Onopkise Amos , Oke Oluwatobi , Agbaroji Victor , Okon Willie
Published: August 2020

Managed by a joint operating team tagged the Asset Management Team (AMT), the OML 26 Asset has undergone a total transformation in all ramifications of the oil and gas operations.

Within the space of three years, the Asset has recorded a 122% cumulative annual growth (CAGR) for reserve base increase, a 43% CAGR in production rate increase without drilling new wells, and a 38% CAGR in total production offtake. The direct unit operating cost also improved significantly averaging 31% year on year improvement. From Q4 of 2018, the Asset witnessed breakthrough performance attaining a peak production of ca 18,000 bopd in 2019 from existing drainage points. The rate is the highest rate ever recorded in the long history of the Asset. This is an excellent achievement for a mid-sized E&P company.

This paper aims to share the techniques deployed to attain such a sterling production boost in a 45-year-old field.
Techno-Economic Assessment of the Hydrates Mitigation Potential of LDHI and MEG in Deepwater Scenario
Authors: Okereke Ndubuisi , Edet Pius , Afolabi Funsho , Baba Yahaya , Izuwa Nkemakolam , Kanshio Sunday , Nwogu Ngozi , Nwanwe Onyebuchi , Odo Jude
Published: August 2020

Previous studies in literature and field experience indicates that hydrates mitigation can increase production cost by 15%. Hence, the need for optimum hydrates inhibitor selection. In this study, a deepwater oil field; currently producing at over 100,000 bbl/d had experienced hydrates and an integrated production modelling approach was utilized to model this scenario via MAXIMUS 6.20. The key input data to model were reservoir pressure at 2650 psia; Oil API Gravity at 35.4 °API; GOR at 1324 scf/stb and the produced water rate at an average of 3138 STB/d. Key results indicates that the injection of LDHI into the hydrate lattice within the hydrocarbon stream dispersed the hydrates particles in an unsteady manner and subsequently prevented the formation of hydrates at 40 gal/day. The cost of using LDHI was lower by over $520/day, from simulation results. This study also assessed technical benefits and challenges of using LDHI and MEG in deepwater scenario.
Rethinking Well Integrity for Sustainability: Adopting a Risk Based Approach
Authors: Adeyinka Adeboye , Tsakporhore Abraham , Arije Oluwaseun , Adegoke Oluwagbemiga , Aliyev Shahin , Iwueze Cosmas , Hulett Robert
Published: August 2020

Loss of containment (LOC) issues are every oil and gas operator's nightmare. These low frequency, high consequence spill-events have the potential to adversely affect the environment, an operator's financial health and public perception. For operators with mature aging assets and a sizeable well count, the probability of a LOC event is more likely.

As the industry moves towards increased efficiency, there is a growing need to get more well integrity projects completed despite competition from oil-generating projects in the company-portfolio. This has necessitated re-thinking our response to the fundamental question of "how can we work within the existing constraints to ensure a robust well integrity program that protects people, the assets and the environment from a LOC event?"

We show in this paper, a risk-based approach to solving this challenge. With over 1000 well strings, the starting point was having a comprehensive well integrity management system underpinned by a robust database that contained the test records of all well-related safety devices. A swiss-cheese model was then applied to analyze each device (Downhole safety valve, Wellhead valves and Casing valves) as a layer of protection considering possible hydrocarbon flow-paths.

With this new methodology, each safety device was assigned a risk-factor denoting its relative importance in preventing the occurrence of a LOC event. Multiple safety device failures (e.g. combined failure of downhole and wellhead valves) had extra penalty assigned since holes lining up in the swiss-cheese would allow a catastrophic event pass through undetected. The risk factors were then summed up for each well to generate a risk-index that was used to compare wells and prioritize barge intervention activities accordingly.

The key message is that catastrophic events typically require multiple safeguard failures and we can significantly reduce the chances of its occurrence by applying a risk-ranked approach to well integrity.
Enhancing NAG Well Surveillance by Realtime Measurement of Condensate-Gas Ratio CGR Using Coriolis Meter
Authors: Ihe Chimdike , Udobata Uchenna , Ogbokuma Ekine , Maheshwari Rahul , Arash Aref , Aja-Onu Uchenna
Published: August 2020

Reliable gas well tests provide valuable data for production optimization and maximizing ultimate recovery of gas reserves. Poor data quality, heightened process safety risks and elevated OPEX are inherent limitations in the methods undertaken by operators to measure Condensate Gas Ratio (CGR) during Multi-Rate Tests (MRT) and routine production.

This paper describes the steps undertaken by the team in BERA to overcome this challenge by utilizing the density-measuring capability of the Coriolis meter. A density-based algorithm was setup using a designed decantation procedure and encoded in the control system for real-time measurements and made available in the office domain.

This technique provides improved data quality, ease of well surveillance and a long-term cost avoiding option while simultaneously increasing the flexibility and ease of executing MRTs. It eliminates the need for manual sampling with its associated process safety concerns.
Effect of Riser Base and Flowline Gas Injection on the Characteristics of Gas-Liquid Two-Phase Flow in a Vertical Riser System
Authors: Brini Ahmed Salem Kalifa , Aliyu Aliyu M. , Ehinmowo Adegboyega , Yeung Hoi
Published: August 2020

We report an experimental study has been conducted on a 52 mm internal diameter vertical riser of which is met at the riser base by a 10.5 m long. The effect of two different gas inlet configurations were tested: riser base gas injection and horizontal inline injection 40 meters upstream of the riser base. A 16×16 wire-mesh sensor was used to measure the void fraction at the riser top and we present a detailed analysis of the characteristics of flow because of the injection scheme. These include regimes and cross-sectional void fraction distributions of the time series data. Among our findings are wall-peaking gas fraction profiles at lower gas injection rates through the flowline, while core-peaking profiles were established at the same flow conditions for riser base injection. This provides valuable information that can feed into the design of downstream facilities such as slug catchers and separators.
Rock Compaction Fault Displacement Evidence from Analysis of Sub-Parallel Subsurface Strata
Authors: Rotimi Oluwatosin John , Zhenli Wang , Liang Yao , Onuh Charles Yunusa , Ogunkunle Temitope Fred , Oyeyemi Kehinde David
Published: August 2020

Sedimentary units often show compaction variation across fault blocks resulting from jarring vertical shortening; a common occurrence in growth fault system innate to the Niger Delta. Rock displacement traceable on slip surface with varied dip was mapped on 3D seismic data. Interpretation done on available well logs reveal existing zones of sand formation that fairly correlates with compaction patterns seen on seismic lines across fault blocks with reference to vertical deviations in horizons across fault planes. These anomalies were stochastically analyzed for its topology effects using Density logs from the field in an attempt to ascertain the influence of rock strata on fault displacement and how this translates to compaction patterns. It was discovered that the effect of differential compaction propelled by wobbly underlying rocks primarily drives the local complexities imaged on the seismic data as varied turgid deformation zones also prolific from computed seismic attributes.
Optimizing Technology Applications with Compatibility Challenges in Remote Operating Environments – A Niger Delta Case Study
Authors: Orogun Elisha , Erivwo Ochuko , Ideh Matthew , Okon Willie , Ageh Ebenezer
Published: August 2020

New Technology implementation brings intrinsic value to well delivery projects with enhanced capabilities for exploitation of hydrocarbon reserves. However, the planning of wells with new technology applications, especially in remote operating locations, comes with unique challenges of compatibility of existing equipment and unavailability of equipment required for the new technology system's deployment.

This paper presents a case study of an engineered approach to equipment modification and retrofitting of wellhead equipment to achieve the required compatibility with a new technology solution identified for a well as a pilot. The limiting conditions encountered in the new technology implementation as presented in the case study are discussed together with the analysis of available concepts to resolve the ensuing gaps and the engineering design of the retrofit solution. The approach not only resulted in significant cost savings but has attendant value creation benefits.

The methodology and thought process presented can be deployed to solve challenges that engineers are confronted with while planning, especially with new technology applications in remote operating environments as was used by OML 26 Asset in the installation of the first ESP artificial lift in the Ogini field.
Understanding the Science of Statistical Log Analysis: A Review of a Practical Workflow Application to Determine Mineral Volume Fraction
Authors: Eriavbe Francis Eseoghene , Okene Uzoamaka Ogochukwu
Published: August 2020

Conventional openhole log evaluation is typically done in a deterministic approach which leads to inherent uncertainty around the derived results based on the fixed assumptions made. This has historically stemmed from the fact that most of the porosity and saturation models utilized in the deterministic work flow were formulated long before the availability of computing processing power. With the advent of technology, statistical methods designed for quantitative formation evaluation of open-hole logs are now easily applicable.

Probabilistic log evaluations are generally done by solving simultaneous equations described by one or more interpretation models. Input log measurements and response parameters are used together with response equations to compute volumetric fractions results for formation components (minerals and fluids alike).

The system of equations built to conduct a volumetric analysis comprises tool parameters, minerals and fluid volumes and the tool responses parameters. The probabilistic workflow uses error minimizing or probabilities to solve a set of over-determined equations for the "best" answer. To achieve an over determined case, constraint equations are often imposed. Logging vendors usually offer this product as part of their service and software applications.

This paper analyses the typical workflow governing probabilistic evaluation methodologies and proposes a Python script based approach that enables the user to run a fast and simple mineral components evaluation based on porosity and basic input logs.

Data from a typical Niger Delta well is used to evaluate the workflow and the results are compared with a deterministic evaluation to see the added benefits.
Modelling Minimum Flow Rate Required for Unloading Liquid in Gas Wells
Authors: Fadairo Adesina , Adeyemi Gbadegesin , Ogunkunle Temitope , Lawal Oreoluwa , Oredeko Olugbenga
Published: August 2020

Liquid loading in gas well has been an interest in the Oil and Gas sector due to the reduction of ultimate recovery and also the reduction of production from such wells. Several authors have presented various models for predicting the beginning of liquid loading in a gas well, yet there are regular errors in the model outcomes. Turner et al. based his critical model on a presumption that liquid droplet is spherical and stays that way throughout the wellbore. Li’s model developed later on based on his postulation that droplets are flat in shape and stays that way throughout the wellbore. In reality, when producing in a gas well, under pressure variation, the liquid droplets alternate between sphere-shape and flat shape. Hence there is a need to incorporate the liquid droplet deformation coefficient in the liquid loading governing equation. The newly presented model considered deformation coefficient to justify irregular changes in liquid droplet due to pressure variation during the simultaneous flow of gas and liquid droplet in gas wells, therefore, predict the critical flowrate correctly as the droplet fluctuates between spherical and flat shape. The results from the newly developed model of the critical flowrate using test data provided by Coleman et al. show that the modified critical flowrate is closer to the test flow rate than the other existing models as the error obtained is -9.12688%.
Effects of Seabed Topography on the Fatigue Life of Steel Catenary Risers
Authors: Uche Amarachi , Okoro Franklin
Published: August 2020

This research work analysed the effects of seabed topography on the fatigue life of a steel catenary riser in the Gulf of Guinea. A fatigue analysis was carried out for two risers namely PFL-06 and PFL-11 on the Portside and starboard sides of an FPSO respectively. A fatigue analysis was run for a flat seabed and a 3-D seabed using Orcaflex’s 3-D seabed feature using the same set of input data. The metocean and environmental data were obtained from Field X riser design document. The fatigue life on the touch-down point for PFL-06 on a flat seabed was calculated as 267 years. On a 3-D modelled seabed, the fatigue life on the touch-down point of PFL-06 is 304 years. For riser PFL-11, the fatigue analysis gave 1231 years and 425 years for a flat and a 3-D seabed respectively. It was observed that since PFL-06 has an outer diameter of 0.324m and almost the same water depth, there was no much difference in the fatigue analysis for a flat seabed and a 3-D seabed. PFL-11 with a smaller outer diameter of 0.273m gave a far lower fatigue life of 425 years on the touch-down point for a 3-D seabed as against a fatigue life of 1231 years on a flat seabed. The maximum effective tension on the TDP for the two risers were lower for a 3-D seabed than a flat seabed. The research found out that assumptions of a flat seabed in the fatigue analysis of the touch down zone of steel catenary risers could have adverse effects in the analysis.
Effect of Microbial Activities on the Viscosity of Heavy crude in Niger Delta Field
Authors: Okotie Sylvester , Onyekonwu Mike Obi , Okpokwasili Gidoen
Published: August 2020

This study focuses on the post-recovery effect of Nigerian heavy crude viscosity in microbial enhanced oil recovery process. The technique involves the injection of exogenous hydrocarbon-degrading microbes with the required nutrients to guarantee the bacteria isolates produce the needed metabolites such as biosurfactants, biopolymer, etc. In this study, thirty- seven hydrocarbon-degrading bacteria were isolated from a hydrocarbon-contaminated soil samples from Gio, Tai Local Government Area in Ogoniland. Three of the bacterial isolates were selected and screened for biopolymer and biosurfactant production using Sudan black solution, oil spreading test, emulsification index, and haemolytic assay. The selected microbes were identified as Bacillus sp, Klebsiella sp & Pseudomonas sp by biochemical analysis. The selected microbes were exposed to ranges of salinity, pH, temperature, nutrient sources, and inoculum concentration to determine their optimum performance in reservoir conditions. The result showed the optimum parameter range for the three microbes: pH 7- 8, a temperature within 25 - 400C and salinity within 0.5% - 5%. The best nitrogen source was peptone while the best carbon source for Bacillus sp was glucose and glycerol for Pseudomonas sp and Klebsiella sp respectively. These optimum parameters were employed in the formulation of the nutrient broth used for the core flooding experiment. The core flooding setup was locally fabricated and calibrated. Fourteen microbial samples of pure and consortium were injected with carbon and nitrogen sources. The result showed an additional recovery range between 18.33% to 29.09% of the pore volume. The post-recovery analysis showed drastic transformation (reduction in viscosity) of the heavy crude to light hydrocarbon components by an average of 20.33% with glucose and 97.27% with peptone.
Prediction of Reservoir Saturation Pressure and Reservoir Type in a Niger Delta Field using Supervised Machine Learning ML Algorithms
Authors: Eyitayo Stella I. , Ekundayo Jamiu M. , Mumuney Eyitayo O.
Published: August 2020

Accurate knowledge of reservoir fluid properties, especially reservoir saturation pressures and reservoir type, is paramount for the estimation of reservoir volumetrics, well design and placement, well and reservoir performance management, field development planning and ultimately economic evaluation of the reservoir. However, most of the existing methods such as PVT fluid sampling, compositional grading, and empirical models have proven to be either ineffective or expensive and sometimes, leads to ungeneralizable results.

This paper discusses the application of machine learning (ML) techniques to develop a robust model for prediction of reservoir fluid properties such as saturation pressures in a Niger Delta Field and the subsequent classification of the reservoirs as under-saturated or saturated. Reservoir data including the PVT data, compositions (C1-C7+), temperature & pressure data, fluids contacts of known reservoir type were considered initially in order to train a model using a multi-features regression ML algorithms for the determination of the saturation pressure and a Two-class boosted decision ML algorithms to determine the determine the type of reservoir (saturated or undersaturated). Of the 34 parameters considered, it was found that the reservoir fluid composition has significant impact in determining the accuracy of the Pb-hypothesis. The key performance indicators such as MAE, RMSE, and RSE are within 0.02-0.05 and Co-efficient of determination of about 95% for Pb determination. When compared with the Standing, Glaso, Petrosky-Farshad etc. correlation, the AAE was significantly less than both cases. AAE for the Standing and Glaso correlations were respectively18.5% and 25.1% while that of the ML model was 2.3% using both the data from training set and test set. For the classification algorithms in determining type of reservoir, the model performed within the 73-100% accuracy, precision & recall. The Area under the curve (AUC) of the Receiver Operator Characteristic (ROC) chart of approximately 97% indicated the robustness of the model. The results showed that the use of a properly trained and accurately validated ML model can deliver better predictions of reservoir fluid properties and subsequent reservoir type when compared to conventional methods.