bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface Complexation Modelling of Potential Determining Ions Sorption on Oil/Brine and Brine/Rock Interfaces
Authors: Adeyemi Bamikole , Jadhawar Prashant , Akanji Lateef
Published: August 2021

Previous studies on smart water effects have suggested wettability alteration as the most significant mechanism for additional oil recovery during smart water injection. Though many other mechanisms have been observed and proposed in several other studies, much more attention is paid to the detachment of oil films from rock surfaces. It is, however, clear from prevailing understanding that the activities at oil/brine interfaces might require as much attention as given to the brine/rock interfaces. This paper presents diffuse double layer surface complexation modelling of the adsorption of potential determining (Ca2+, Mg2+ and SO42-) ions on oil carboxylic and carbonate surfaces.

Surface complexation models are developed by defining the adsorption sites, surface area and mass of the oil and carbonate surfaces. The chemical reactions involving the surface sites and five different brine solutions are also defined. The brine solutions include formation water, sea water, sea water diluted 20 and 50 times, and sea water with four times SO42- concentration. The amount of the divalent ions adsorbed at pH range of 5 to 8 are determined after the reactions had reached equilibrium. Adsorption of the ions on oil carboxylic and carbonate surfaces at elevated temperature for the sea water is also investigated.

Results show that significant number of divalent ions are collected at the oil/brine interfaces just as adsorbed at the brine/rock interfaces. The results suggest that the equilibrium reactions and the dynamics at the two mathematical interfaces in any oil/brine/rock systems are equally important to reach a full understanding of the main mechanisms behind smart water effects. Therefore, the dynamics of ionic reactions at the oil/brine interface can play critical roles in defining smart water effects on residual oil mobilization.
Pressures and Pressure Derivatives of a Vertical Well Located Within Two Inclined Faults: Case Study of Basic Angles and Unequal Well Distances from Faults
Authors: Ojah Michael , Adewole Steve
Published: August 2021

Pressure transient analysis has been used to evaluate performance of a vertical well located within two intersecting sealing faults. The nature and types of boundary affect productivity in bounded reservoirs. Well performance is strongly affected by well location with respect to the boundary, be it single, paired and parallel or paired and inclined. The goal of this research was to study pressure behavior as well as performance of a vertical well located within two intersecting sealing faults inclined at various angles θ and at unequal distances to faults. Unlike similar works previously carried out, this work can be used to study or predict pressure distribution of a well in a wedge system located at unequal distances to faults. Using the concept of images, the study proposed new models for estimating distances between image well(s) and active well. These models were applied in the solution to the dimensionless diffusivity equation to characterize pressure transient behavior of a well located at unequal distances to the inclined faults. These pressures and pressure derivatives were computed from the total pressure drop expression summing all the image wells by the principle of superposition. The MATLAB, Python and Excel software were deployed to compute all the dimensionless pressures for the different well designs. The results obtained show that 1) the proposed models give accurate estimation of active well distances to image wells; 2) the models show that the distance between the active and image wells d0,i increases for the range of values of angles 0°< θ0,i ≤ 180° and decreases for the range 180° < θ0,i < 360°; 3) the relationship between unequal well distances and productivity has a maximum point; 4) beyond this point, the well ceases to be productive and; 5) this maximum point is at equal distances of the well from both faults, in this case, 15 ft. Larger magnitudes of dimensionless pressure derivatives would indicate higher oil production for any well design and inclination of the boundaries. Worthy of future works are similar studies on 1) horizontal wells and 2) mixed boundaries, that is, one sealing fault and one constant pressure boundary.
Regulatory Requirements for Accuracy in Flare Gas Measurement – Synergizing Software Method Advancement to assist the Hardware Technology to meet Accuracy Demands
Authors: Umeh Ebuka , Ibeh Stanley , Obah Boniface , Abonyi Chukwunonso , Nnakaihe Stephen
Published: August 2021

Over the years, the industry has been so used to the hard logic of utilizing flare gas meters (notably the ultrasonic flare gas meters) in the measurement of stranded flare gas. This is because it has been a workable solution for years with minimal challenges due to the broader range of accuracy required by regulatory bodies. Usually, companies are either constrained to either utilize the associated gas from the oil and gas facilities as fuel gas to power up the unit or reinject in the reservoir to serve as pressure maintenance agent that pushes the oil towards the reservoir, or stored in the reservoir and/or flare the gas (which in most cases, have been deployed by operators despite the penalties by the regulatory organization). With the recent steer in carbon capture, natural gas utilization, climate change and energy transition, accuracy level demands has been made more stringent with some countries including Nigeria requesting for 2.5 – 3% accuracy level of measurement from operators in a bid to monitor and curb the essence flue gases that are unaccounted for. This can only be for gases flared during routine conditions which does include when process upsets give rise to shut down and blowdown of gases through the flare header to the flare tip.

The high demand of measurement accuracy has opened windows for OEM to produce calibrated meters that are bespoke with a longer timeline for recalibration as most of the hardware in critical operations could require a process shutdown to either maintain, repair, calibrate or even replace. With this growing concerns in the industry and the surging growth of digitalization involving AI, data analytics etc in other areas, the software method would be a potential source of synergy to assist the failing hardware which are being impacted by time as calibration issues continue to resurface throughout the life of the meters, giving rise to wider accuracy measurement in the region 5 – 10%, hence attracting the hammer from the regulators.

This paper is intended to produce a deep dive of the current regulatory requirements for gas measurement in Nigeria by the regulators (DPR), the impact of the recent 3% accuracy requirements as it impacts both large and medium size operators, the role of gas measurement software for bridging the gaps and shortfalls of the hardware components. A case study of newly developed flare gas measurement software and its impact in assisting operators in gas performance reporting, production allocation and flare penalties where applicable
Overcoming Challenges of Pigging the Unpiggable Pipelines
Authors: Oragwu Chinedu , Molyneux Daniel , Lawal Lukeman , Ameh Stanley
Published: August 2021

Carbon steel pipelines are used to transport hydrocarbons globally because carbon steel is relatively easier to fabricate, safe for use, raw materials are available and less expensive. Amidst these benefits, carbon steel is susceptible to severe corrosion and other anomalies. Pipeline corrosion is a significant concern in the oil and gas industry. It has caused several minor and catastrophic losses of containment with resultant fatalities, environmental pollutions, asset damage, and production downtimes.

The increasing failures of in-service pipelines have led the Department of Petroleum Resources (DPR) to intensify regulatory scrutiny of pipeline integrity assessment and management in Nigeria to ensure strict compliance to the regulatory requirements by the Oil Producing Companies. According to DPR Act (Section 2.5.2.1), all pipelines greater than 6" size diameter must be inspected every five (5) years with intelligent pigs (inline inspection tools) that would provide the accurate condition of the pipeline. However, many pipelines in Nigeria are unpiggable or difficult to inspect with intelligent pigs due to the unavailability of pigging facilities (especially in brownfields), pipelines with short bend radiuses, dual diameters, flow parameters, etcetera.

This paper explores case studies involving the use of advanced inline inspection technology to conduct inline inspection of difficult-to-inspect dual-diameter pipelines.
Undersaturated Hydrocarbon Reservoir Waterflooding: A simulation Approach to Performance Assessment
Authors: Adeniyi Adekunle Tirimisiyu , Osatemple Miracle Imwonsa , Giwa Abdulwahab
Published: August 2021

There are a good numbers of brown hydrocarbon reservoirs, with a substantial amount of bypassed oil. These reservoirs are said to be brown, because a huge chunk of its recoverable oil have been produced. Since a significant number of prominent oil fields are matured and the number of new discoveries is declining, it is imperative to assess performances of waterflooding in such reservoirs; taking an undersaturated reservoir as a case study. It should be recalled that Waterflooding is widely accepted and used as a means of secondary oil recovery method, sometimes after depletion of primary energy sources. The effects of permeability distribution on flood performances is of concerns in this study. The presence of high permeability streaks could lead to an early water breakthrough at the producers, thus reducing the sweep efficiency in the field. A solution approach adopted in this study was reserve water injection. A reverse approach because, a producing well is converted to water injector while water injector well is converted to oil producing well. This optimization method was applied to a waterflood process carried out on a reservoir field developed by a two - spot recovery design in the Niger Delta area of Nigeria that is being used as a case study. Simulation runs were carried out with a commercial reservoir oil simulator. The result showed an increase in oil production with a significant reduction in water-cut. The Net Present Value, NPV, of the project was re-evaluated with present oil production. The results of the waterflood optimization revealed that an increase in the net present value of up to 20% and an increase in cumulative production of up to 27% from the base case was achieved. The cost of produced water treatment for re-injection and rated higher water pump had little impact on the overall project economy. Therefore, it can conclude that changes in well status in wells status in an heterogenous hydrocarbon reservoir will increase oil production.
The Commercial Potentials of Underground Natural Gas Storage in Nigeria
Authors: Adegun Adedamola , Rufai Femi
Published: August 2021

Nigeria is the 2nd biggest natural gas producer in Africa, with much of it exported as LNG, some re-injected while a small fraction serves the domestic market. The volume supplied to the domestic market plays an outsized role in the energy mix and economy of Nigeria with over 90% supplied to thermal power plants and industrial clusters. As huge upstream gas projects continue to take Final Investment Decision, pipeline takeaway capacity grows and demand increases, the dependence on natural gas and preponderance in the energy mix will likely persist. Natural gas is the present and future of Nigeria's energy needs.

The domestic gas industry is evolving but has been fraught with challenges. Oil and gas infrastructure are often disrupted and production shut-in, mostly triggered by infrastructure unavailablity, environmental concerns and prioritisation of hydro power generation during River Niger's white and black floods, all of which come at a cost to upstream producers. Gas producers are often compelled to curtail production of gas plants (associated and non-associated) to avoid environmental disasters and prohibitive gas flare penalties. Can underground gas storage (UGS) be an opportunity for gas producers to guarantee continued operations during disruptions and provide buffer for national strategic benefits?

This paper seeks to explore the potential technical and economic dynamics of underground natural gas storage in Nigeria in the context of extant technical regulations, seasonal demand variations, gas flare penalties and local operating environment. The paper presents types of underground storages and recommends the most suitable, considers options for optimal location of UGS in Nigeria and undertakes an economic evaluation of a UGS project. The findings are further presented alongside the critical technical, regulatory and fiscal factors that may facilitate future investments and growth of underground gas storage in Nigeria.
Computer Implementation of the Dykstra-Parsons Method of Waterflood Calculation
Authors: Lekia Prosper Kiisi
Published: August 2021

One of the challenges of the petroleum industry is achieving maximum recovery from oil reservoirs. The natural energy of the reservoir, primary recoveries in most cases do not exceed 20%. To improve recovery, secondary recovery techniques are employed. With secondary recovery techniques such as waterflooding, an incremental recovery ranging from 15 to 25% can be achieved. Several theories and methods have been developed for predicting waterflood performance.

The Dykstra-Parson technique stands as the most widely used of these methods. The authors developed a discrete, analytical solution from which the vertical coverage, water-oil ratio, cumulative oil produced, cumulative water produced and injected, and the time required for injection was determined. Reznik et al extended the work of Dykstra and Parson to include exact, analytical, continuous solutions, with explicit solutions for time, constant injection pressure, and constant overall injection rate conditions, property time, real or process time, with the assumption of piston-like displacement.

This work presents a computer implementation to compare the results of the Dykstra and Parson method, and the Reznik et al extension. A user-friendly graphical user interface executable application has been developed for both methods using Python 3. The application provides an interactive GUI output for graphs and tables with the python matplotlib module, and Pandastable. The GUI was built with Tkinter and converted to an executable desktop application using Pyinstaller and the Nullsoft Scriptable Install System, to serve as a hands-on tool for petroleum engineers and the industry.

The results of the program for both methods gave a close match with that obtained from the simulation performed with Flow (Open Porous Media). The results provided more insight into the underlying principles and applications of the methods.
Applications of AI and Data-Driven Modeling in Energy Production and Marketing Processes
Authors: Ugoyah Joy , Igbine Anita Mary
Published: August 2021

Faster and more accurate decisions are what the Oil and Gas industry needs with the world's fast-evolving energy needs and economy. The area of Artificial intelligence and Data-driven modelling is relatively new and has not found popular application in the industry. AI is an emerging technology that can be used to predict event outcomes and automate anomaly-detection processes.

The various applications of AI in different industries were researched into. This paper highlighted important processes that can be improved with the application of Artificial Intelligence through data-driven modelling. It also highlights areas in the various industries where AI intelligence is already being applied and ways it can be improved.

AI and data-driven modelling has the potential to improve exploration accuracy, reduce production down-time, reduce cost of maintenance, and reduce health and safety risks.

This body of information can serve as a guideline for adopting AI in the oil and gas industry. A trend of industry-tailored intelligence solutions would be more effective in the evolving energy industry.
Non-Edible Oil Based Surfactant For Enhanced Oil Recovery
Authors: Adeniyi Adekunle Tirimisiyu , Onyemaechi Ijoma
Published: August 2021

After the primary and secondary oil recoveries, a substantial amount of oil is left in the reservoir which can be recovered by tertiary methods like the Alkaline-Surfactant Flood. Reasons for having some unproduced hydrocarbon in the reservoir include and not limited to the following; forces of attraction fluid contacts, low permeability, high viscous fluid, poor swept efficiency, etc. Although, it is possible to commence waterflooding together chemical injection at the start of production. Reservoir simulation with commercial simulator, could guide in selecting the most appropriate period to commence chemical flooding. In this study, the performance of a new synthetic surfactant produced from Jatropha Curcas seed was compared with that of a selected commercial surfactant in the presence of an alkaline and this shows that the non-edible Jatropha oil is a natural, inexpensive and a renewable source of energy for the production of anionic surfactants and a good substitute for commercial surfactants like Sodium Dodecyl Sulphate (SDS). The Methyl Ester Sulfonate (MES) surfactant showed no precipitation or cloudiness during stability test and was able to reduce the Interfacial Tension (IFT) to 0.018 mN/m and 0.020 mN/m in the presence of sodium carbonate and sodium hydroxide respectively as alkaline at low surfactant concentration. The optimum alkaline surfactant formulation in terms of oil recovery performance obtained from the core flooding experiment corresponds to a concentration of sodium carbonate (0.5wt%), sodium hydroxide (0.5wt%) mixed in distilled water and Methyl Ester Sulfonate (MES) surfactant (1wt%). The injection of 0.5 percentage volume of alkaline surfactant slug produced an incremental oil recovery of 26.7% and 29% respectively. With these incremental oil recoveries, increasing demand for hydrocarbons product could be met, and returns on investment portfolio will be improved.
Analytical Model for Estimation of Pore Volume to Breakthrough in Carbonate Acidizing with Organic and Mineral Acids
Authors: Lohrasb Sina , Junin Radzuan , Agi Augustine , Jaafar Mohd Zaidi , Gbadamosi Afeez , Sidek Mohd Akhmal , Gbonhinbor Jeffrey , Oseh Jeffrey , Yakasai Faruk
Published: August 2021

Acidizing is one of the most useful methods in the oil well stimulations. This treatment technique creates capillary wormholes in the carbonate formations to enhanced fluids flow production of a reservoir. One of the main indexes for recognizing the wormhole characterization is the pore volume to breakthrough number. Therefore, calculating this number is one of the main goals in the carbonate acidizing. Obtaining this number is always required for experimental works, which needs time, energy and cost. In this article, an empirical model was used to evaluate carbonate acidizing procedure in the limestone and dolomite cores as the carbonate cores. This empirical model measures the number of wormholes formed in the carbonate cores after acid injection by using the conservation of mass law. In this method, the transport relative reaction rates of acid and core inside the structure of wormhole was maintained during the wormhole creation process. Growing the wormhole in the carbonate formation was developed step by step. Changes in acid concentration as an injected fluid flow were accounted for in this empirical model. Also, the changes in carbonate porosity, the effect of Damköhler number, and injection rate were included in the model. Two types of carbonate rocks and five types of acids with different molar masses were used in this model for the analysis and validation of the model. The results from experimental works was significance and justifies the use of use of the law for mass transport and chemical reactions. Evaluation of the developed model with other experimental and numerical results gave an excellent assessment of 95.45% for the average accuracy and 0.9933 for the average coefficient of determination. Therefore, an empirical technique to approximate the pore volumes to breakthrough number in the limestone and dolomite cores with high accuracy using physical core and acid properties is proposed.
Delineating Depositional Environment through Lithostratigraphy and 2D Sequence Stratigraphy of a Typical Ramp Succession: In the Obom Field Niger Delta
Authors: Okobiebi Onome , Okobiebi Becky
Published: August 2021

Modelling the most appropriate depositional environment is essential in the reservoir characterisation and 3D modelling of oil bearing sands and the integration of various workflows reduces the uncertainty in deciding the appropriate depositional model which serves as a precursor into petrophysical property distribution during 3D modelling. This paper elaborates a robust study of the integration facies analysis, 2D sequence Stratigraphy and biostratigraphy data in depicting the environment of deposition of the OBOM field. The lithological description of the G8 to the F5 reservoirs ranged from finning upward sequence and blocky shaped sequence as channel sands and coursing upward shoreface deposits. Mineralogical descriptions of the penetrated sands were also carried out, especially on the F5 reservoir in which the presence of radioactive minerals was decisive to constrain the depositional environment to lower shoreface. In the Sequence stratigraphic analysis two 3rd Order depositional cycles was identified from top to bottom in the field. This is substantiated by the facies trend, facies cross plot and cycles indicators like maximum flooding surfaces identified by regional marker shales, biofacies population and biodiversity charts and sequence stratigraphic methods like sequence thickness, bed stacking patterns and facies depositional patterns with regards sea level change. It was noticed that reservoir thickness reduces from the bottom to the top with the proximal channel sands in deep intervals gradually overlain by distal upper shoreface sands and lower shoreface sands at the shallower intervals. The gross depositional environment was a transgressive marine settings ranging from the lower shoreface and channelized upper shoreface deposits. The results from the integration of facies analysis, biofacies, seismic analysis and sequence stratigraphy results reduces uncertainty in depositional environment models.
An Assessment of Opportunities and Challenges of Natural Gas Utilization in Ghana
Authors: Morgan Theresa Ahima , Oppong Dr.Riverson. Riverson
Published: August 2021

This study aims to contribute to industry discussion on gas utilization opportunities available to Ghana. Specifically, it will analyze Ghana's existing natural gas plans. i.e., the Gas Master Plan analyze possible opportunities and associated challenges and finally propose sources of finance for gas sector projects.

In order to discover opportunities of natural gas utilization as well as challenges that come in the course of implementation, data was sourced from secondary sources as well. Benchmarking was also done using the natural gas journeys of three (3) case study countries: Nigeria, China, and the United Kingdom and a comparative analysis compared their natural gas journeys in terms of policy direction, natural gas utilization, infrastructure development and challenges encountered vis a vis the natural gas journey of Ghana.

The analysis showed that various opportunities existed for natural gas utilization in the areas of industrial power generation, LNG export, CNG, Fertilizer and bauxite production. Various challenges such as lack of human and technical capacity, sector debt, regulatory issues, pricing issues, security of supply and others plagued most natural gas economies.

These findings suggest that an ‘armory’ of opportunities exist for natural gas utilization in Ghana. However, the implementation of these utilization options is contingent on the development of proper policy instruments and extensive investment in infrastructure. The country should also be conscious of bottlenecks that may hinder natural gas utilization efforts.
Impact of the Petroleum, Local Content and Local Participation Regulation 2013, Li 2204 on Local Skills Development in Ghana's Upstream Oil & Gas Sector
Authors: Oppong Riverson , Amoah-Awuah Nixon
Published: August 2021

This study was to assess how the implementation of LI 2201 has impacted the development of local skills in the sector. The study focused on the two producing International Oil Companies (IOCs) and the Petroleum Commission (PC). Data gathered were gathered using the mixed approach and analysed using descriptive analysis. The study revealed that the IOCs have put several initiatives in place to recruit and develop Ghanaians for key positions in their organization. These initiatives have resulted in forty six percent (46%) of Management staff, seventy four percent (74%) of Core Technical staff and ninety four percent (94%) of Other Support staff in their organisations combined being Ghanaians. The PC has also initiated a number of initiatives which are building the needed vocational skills as well as practical experience of Ghanaians and have led to localization of some positions within the sector.

Despite the successes achieve so far, there are challenges facing the PC and the IOCs which make it difficult for the sector to achieve the full intent of LI 2204. Key among the challenges are lack of required local skills, high skills development cost, lack of cooperation among key stakeholders and limited practical development opportunities which need to be addressed to be able to achieve the key intent of the Regulations. These challenges have been acknowledged by The PC and have set up an internal committee headed by the Director of Localisation to look into ways in which localization can be improved.
Modelling the Spread of Covid-19 in a Typical Oil and Gas Facility Setting
Authors: Okafor Emeka , Bass Brad
Published: August 2021

The spread of infectious diseases such as COVID-19 in a typical oil and gas facility setting, the health of employees, their families and their communities, is of real concern to the industry. In this work, a suitable predictive, agent-based model is used to predict the spread of COVID-19 in different settings as well as to evaluate strategies to block the spread. The agent-based modelling work is based on the simulation platform, Complex Organization and Bifurcation Within Environmental Bounds, or COBWEB. COBWEB simulates how a system of autonomous agents adapts to variation and sudden changes in the resource base or other features of their environment. Previous COBWEB simulation results illustrate that the tool is useful for predicting the evolution of COVID-19 spread and the effectiveness of various preventive actions including self-isolation of symptomatic people, social/physical distancing, effective PPE use, and ‘shielding’ (physical isolation) of the high-risk population. We adapted model parameters to better represent uncertainty about what might be expected in such a setting, in particular by shifting the distribution of risk severity towards ineffective PPE use, self-isolation and poor social distancing, which expectedly shows upward trend of the spread of the COVID-19. Ultimately, governments and industry can apply the predicted trends, as well as apply the model to specific settings, to make more informed decisions on the additional measures and preventative strategies to curb the spread of COVID-19.
Decommissioning of Offshore Oil and Gas Facilities: A Comparative Study Between Malaysia Practices and International Standards
Authors: Kumar Shaleni , Sidek Mohd-Akmal , Agi Augustine , Junin Radzuan , Jaafar Mohd-Zaidi , Gbadamosi Afeez , Gbonhinbor Jeffrey , Oseh Jeffrey , Yakasai Faruk
Published: August 2021

Regulations for decommissioning are bound by international and domestic regulations. There are numerous decommissioning concepts to choose from, such as complete or partial removal, structure severance options which leave behind shell mounds and drill cuttings. However, in several international regulations there appears to be little clarity and/or opposing ideologies. Malaysia and Thailand have accessible resources for decommissioning legislation or guidelines in South East Asia. Nevertheless, they are differences in the regulations of these countries regarding the legal framework, the technical, financial and environmental framework. In this study, the feasibility of existing framework in decommissioning process of offshore installations or structures in Malaysia was studied and compared with international practices. Decision matrix analysis was used to systematically identify, analyse, and rate the performance of relationships between sets of values and information. Moreover, the scale of decommissioning activities over the next years, the data and information obtained were analysed using descriptive statistics approach. The results indicated that Thailand had the best decommissioning regulations because they have strict regulation in decommissioning. Most of the regulations covering the technical section are similar within all countries studied. Finally, recommendations given are from the aspects of frameworks on in-situ full or partial decommissioning, clarity on liabilities and residual risk management, financial security, residual risk funds, workflow optimisation, information management system, and waste management.
Mechanically Enhanced Cementing: Mitigation Against Sustained Casing Pressure in Highly Stressed Downhole Environment, Offshore Niger Delta
Authors: Abdulsalaam Ilyas , Amos Chibuzor , Ahabike Grace , Ejukorlem-Okusi Rebecca
Published: August 2021

A major Exploration and Production (E & P) company was posed with a challenge of sustained casing pressure in over 85% of the wells drilled in one of the fields in the Offshore Niger Delta. Sustained casing pressure occurs when the annular seal is damaged and a path is created for the formation pressure to reach the surface, and the pressure in the annulus rebuilds after being bled down.

When cementing in such an environment, operators have the following objectives: Placing a cement sheath with increased capability to survive future downhole stress events.Achieving effective mud removal.Gaining the benefits of a react and respond sheath design.Providing a long productive life for the wellbore.

To develop a cement system that would achieve and maintain isolation throughout the life of the well, an advanced cement technology was required. This advanced cement technology involved Finite Element Analysis (FEA) to model the effects of stresses from well operations on the cement sheath.

This analysis takes into consideration well configuration, formation properties, casing properties, cement properties and operational loads and predicts the remaining capacities of the cement sheath. The remaining capacity is used to measure how much a cement sheath is stressed. After simulating the effect of downhole stresses on a cement sheath, a mechanically enhanced cement slurry was designed to meet the recommendations of the model and provide a cement sheath with improved remaining capacity.

This paper presents the successful mechanically enhanced slurry design, job design, planning and execution on the production section of the well after a Finite Element Analysis was conducted.

Post job conditions such as good cement bonds across cemented areas, well production without inter-zonal communication and no annular pressure build up in over 8 years have proven the success of the design and the procedure implemented in these challenging well bore environments. The success of this well has been applied to two additional wells.
Sequential Prediction of Drilling Fluid Loss Using Support Vector Machine and Decision Tree Methods
Authors: Rotimi Oluwatosin John , Ukwu David Nnaemeka , Zhenli Wang , Liang Yao , Ameloko Anthony A. , Ogunkunle Temitope Fred , Oyeyemi Kehinde David , Kouamelan Kouamelan Serge , Asaboro Ufouma Frank , Onuigbo Ifunanya Sylvia
Published: August 2021

Machine learning methods have been applied to predict depths of fluid loss in hydrocarbon exploration.During drilling, lost circulation can be described as the unpleasant loss of all or part of drilling mud or fluid into the immediate formations or affected formation by excessive hydrostatic pressure, sufficient to fracture the formation or expand existing fractures encountered during the drilling process. In this study, we deployed Python codes of Support Vector Machine (SVM) and Decision Tree (DT) methodsto categorical data obtained from drilling operations in a producing field to predict lost circulation occurrence. The modelsleveraged the capability of both SVM and DT to achieve binary classification by adopting flow-out percentage of less than 70 percent as the points of lost circulation. That is, < 70% is represented as Loss and > 70% represented asNo Loss. Prediction models were applied to 10 input variables preprocessed with principal component analysis (PCA) to reduce dimensionality and focus on essential variables. The preprocessed SVM model gave an improved result while preprocessing does not affect DT models. Overall, DT models predicted accurate fluid losszones and can be scaled up to field operations with options ofcontinuous sampled variables.
Managing Wellbore Stability Window and Well Integrity by Adjusting the Tight Margin to Successfully Drill through Naturally Fractured Zone Onshore Niger Delta
Authors: Akong Bassey , Orimoloye Samuel , Otutu Friday , Ojo Akinwale , Mfonnom Goodluck , Mrakpor Ovie , Obasuyi Edward , Samuel Ogba , Oladoyin Olumide
Published: August 2021

The analysis of wellbore stability in gas wells is vital for effective drilling operations, especially in Brown fields and for modern drilling technologies. Tensile failure mode of Wellbore stability problems usually occur when drilling through hydrocarbon formations such as shale, unconsolidated sandstone, sand units, natural fractured formations and HPHT formations with narrow safety mud window. These problems can significantly affect drilling time, costs and the whole drilling operations. In the case of the candidate onshore gas well Niger Delta, there was severe lost circulation events and gas cut mud while drilling. However, there was need for a consistent adjustment of the tight drilling margin, flow, and mud rheology to allow for effective filter-cake formation around the penetrated natural fractures and traversed depleted intervals without jeopardizing the well integrity. Several assumptions were validly made for formations with voids or natural fractures, because the presence of these geological features influenced rock anisotropic properties, wellbore stress concentration and failure behavior with end point of partial – to-total loss circulation events. This was a complicated phenomenon, because the pre-drilled stress distribution simulation around the candidate wellbore was investigated to be affected by factors such as rock properties, far-field principal stresses, wellbore trajectory, formation pore pressure, reservoir and drilling fluids properties and time without much interest on traversing through voids or naturally fractured layers. This study reviews the major causes of the severe losses encountered, the adopted fractured permeability mid-line mudweight window mitigation process, stress caging strategies and other operational decisions adopted to further salvage and drill through the naturally fractured and depleted intervals, hence regaining the well integrity by reducing NPT and promoting well-early-time-production for the onshore gas well Niger Delta.
Nigerian Gas Transportation Network Code NGTNC; Emerging Opportunities for Local Gas Transmission Operations
Authors: Bashir Shehu Umar , Idris Farouk , Usman Kamalluddeen
Published: August 2021

Historically, both regulatory and contractual constraints have inhibited the overall optimization of natural gas transmission systems. The Nigerian National Petroleum Corporation (NNPC) currently supplies gas either as source of fuel or as feedstock to different industries. More local industries are now aware of the advantages and benefits of using gas; hence creating an increase in demand. Recent changes in the regulatory framework and the introduction of the Nigeria Gas Transportation Network Code (NGTNC) to deepen the growth of gas market in the country are however, fostering the pipeline companies into a new competitive position, creating strong incentives as well as opportunities. This work provides a section-by-section summary of the Code for the benefit of those who are passionate about understanding the nuances of the Code and of course makes cogent survey and recommendations, to expedite the success of the Code. In the course of this research, questionnaires were administered and 130 respondents were chosen based on their level of knowledge and experience in the industry ranging from operations, management, regulatory and Gas Associations. Responses were collated and analysed using simple statistical tools, tables, and graphs to identify opportunities. The result of the study illustrates the stakeholder's presumption and commitments in using NGTNC for optimized Gas transmission operations.
Evaluation of Machine-Learning Tools for Predicting Sand Production
Authors: Ngwashi Afungchwi Ronald , Ogbe David O. , Udebhulu Dickson O.
Published: August 2021

Data analytics has only recently picked the interest of the oil and gas industry as it has made data visualization much simpler, faster, and cost-effective. This is driven by the promising innovative techniques in developing artificial intelligence and machine-learning tools to provide sustainable solutions to ever-increasing problems of the petroleum industry activities. Sand production is one of these real issues faced by the oil and gas industry. Understanding whether a well will produce sand or not is the foundation of every completion job in sandstone formations. The Niger Delta Province is a region characterized by friable and unconsolidated sandstones, therefore it's more prone to sanding. It is economically unattractive in this region to design sand equipment for a well that will not produce sand.

This paper is aimed at developing a fast and more accurate machine-learning algorithm to predict sanding in sandstone formations. A two-layered Artificial Neural Network (ANN) with back-propagation algorithm was developed using PYTHON programming language. The algorithm uses 11 geological and reservoir parameters that are associated with the onset of sanding. These parameters include depth, overburden, pore pressure, maximum and minimum horizontal stresses, well azimuth, well inclination, Poisson's ratio, Young's Modulus, friction angle, and shale content. Data typical of the Niger Delta were collected to validate the algorithm. The data was further split into a training set (70%) and a test set (30%). Statistical analyses of the data yielded correlations between the parameters and were plotted for better visualization.

The accuracy of the ANN algorithm is found to depend on the number of parameters, number of epochs, and the size of the data set. For a completion engineer, the answer to the question of whether or not a well will require sand production control is binary-either a well will produce sand or it does not. Support vector machines (SVM) are known to be better suited as the machine-learning tools for binary identification. This study also presents a comparative analysis between ANN and SVM models as tools for predicting sand production. Analysis of the Niger Delta data set indicated that SVM outperformed ANN model even when the training data set is sparse. Using the 30% test set, ANN gives an accuracy, precision, recall, and F1 - Score of about 80% while the SVM performance was 100% for the four metrics. It is then concluded that machine learning tools such as ANN with back-propagation and SVM are simple, accurate, and easy-to-use tools for effectively predicting sand production.
A Comparative Study of Soft String Vs Stiff String Models Application in Torque and Drag Analysis
Authors: Ohia Nnaemeka Princewill , Ekwueme Stanley Toochukwu , Achumba Gabriel Ifeanyi , Okereke Ndubuisi Okechukwu , Nwankwo Ifeanyi Valerian , Nnwanwe Onyebuchi Ivan
Published: August 2021

Torque and drag models estimate downhole forces, torques and moments acting in wellbores and drillstring elements during drilling and completion operations. A comparison was made between soft string and stiff string torque and drag model using conventional survey data. Survey data needed for torque and drag modeling are provided by field surveys. Field survey can be conventional survey or continuous survey. Conventional survey is carried out every 90 to 100ft interval or more and only gives a partial representation of the actual wellpath, micro-doglegs and micro-tortuosities may not be fully captured with this survey. Continuous survey is carried out between 1 to 5ft intervals of the wellbore using high resolution survey tools and captures more the micro-doglegs and micro-tortuosities but more expensive than the conventional survey. Torque and drag simulations were performed using both Soft and Stiff String models for comparison using a novel software package. Data provided includes deviational survey data from conventional survey, drillstring/BHA data, and fluid rheological data. The torque and drag simulation produced results for hook loads and buckling while running-in-hole (RIH) and pulling-out-of-hole (POOH). Results from this study show that prior to buckling, results from soft string and stiff string model are almost identical with minimal differences within the range of 0.8% to 1.6% and these were achieved as open-hole friction factors (CHFF) from 0.1 to 0.25. High buckling risk was detected for OHFF of 0.3. When buckling occurs, the differences in results between the two models become very apparent. This paper showed that in order to use stiff string torque and drag model for a more realistic, representative and more accurate pre-buckling and post-buckling operations in a highly deviated well, a high resolution continuous survey is needed; this will capture more readily, the micro-doglegs and micro-tortuosities in the wellbore paths.
Effecting a Pneumatic Operated Assembly, for an Improved Oil Recovery IOR, in Onshore Wells
Authors: Ishaya, Wakili Abednego
Published: August 2021

As hydrocarbon formation continues, owing to its natural sourcing, technologies have continually emerged on how these hydrocarbons can be effectively produced at a commercial benchmark. Asides its natural drive system, the enhanced oil recovery methods have been one key approach that has been effected towards increasing hydrocarbon's production rate, from its reservoirs. The natural reservoir energy has allowed for about 10% production of original oil in place. And, extending a field's productive life by employing the secondary recovery has further improved production to 20 to 40%, with EOR amounting to about 30 to 60% production.

This however, would tell of the impending need towards further developments on increasing upon this production rate. Hence, the approach on using a pneumatic operated assembly with considerations made on onshore wells. This paper seeks to depict a focal on "Pneumatic IOR (Improved Oil Recovery)" as a method to be effected for onshore wells towards improving its productivity.

The pneumatic system uses compressed air, contained in a cylinder - through specialized tubing, alongside pressure control systems, that helps regulate the flow and amount of the compressed air; to propel a metallic bar that will act on the reservoir surface. A force of impact, which will induce vibrations inwards, is generated. The mechanical motion of the metal bars for which this compressed air acts upon will provide the travel force, which when it acts on the reservoir surface of interest, will induce geologic stresses. This stresses and vibrations are important constituents in increasing pressure, downhole. Thereby, enabling fluid flow upwards through the wellbore to the surface.

And, this will proffer the necessary physics, needed for pressure development downhole, which will be of importance in improving Oil Recovery.
Analysis of Critical Buckling Loads For Tool-Jointed Drillstrings in Deviated Wellbores
Authors: Ohia Nnaemeka Princewill , Ekwueme Stanley Toochukwu , Achumba Gabriel Ifeanyi , Okereke Ndubuisi Okechukwu , Nwankwo Ifeanyi Valerian , Nnwanwe Onyebuchi Ivan
Published: August 2021

Excessive torque and drag, buckling and shear forces on downhole strings and tubulars are often encountered in the drilling of longer reach or deviational wells. Buckling of drillstring and BHA occurs in drillstring mainly due to high compressive forces. A point may be reached where these compressive forces rise and exceed the critical buckling loads leading to buckling of the drillstring/BHA or tubulars. This study focuses on the evaluation of the effect of tool-joint on the buckling of drillstrings for highly deviated wells. Tool-joint in pipes changes the pipes geometry in the wellbore thus affecting its hydraulics, orientation and stress distribution. A notable error will arise when straight pipe (with uniform outside diameter (OD) models are used to model pipes with end couplings and connections (such as tool joints). These errors may impact critical buckling loads, buckling initiation points, and post-buckling analysis of the pipe or BHA, thus affecting the success of drilling and completion operations. Torque and drag simulation and analysis was carried out for drillstring and BHA components in 9 5/8 in casing and 8.5 in open-hole sections to determine buckling loads. Two cases were considered; case 1 investigated the modeling and definition of buckling conditions for single straight body drillstrings and case 2 evaluated the buckling conditions for tool-jointed pipes. The result shows that buckling in tool-jointed pipes follows similar trend to that of straight body pipes with sinusoidal or lateral buckling being initiated first, and gradually progresses to helical buckling on increased axial force transfer. Furthermore, from the comparison of the results from two cases considered, it was observed that the presence tool-joint in the pipes led to a critical buckling load of 5.8% for sinusoidal buckling modes. The paper suggests that higher compressive force is needed to buckle the tool-jointed ends of the drillstring than the straight ends.