bluuebunny/crossref_metadata_2025 huggingface dataset:
In-Situ Burning As An Oil Spill Control Measure And Its Effect On The Environment
Authors: Ekperusi Abraham O. , Onyena Amarachi P. , Akpudo Marvellous Y. , Peter Chibuike C. , Akpoduado Christiana O. , Ekperusi Omesiri H.
Published: July 2019

In-situ burning (ISB) is a process of burning crude oil at the point of spill, as a containment measure for oil spill control. It is usually applied as one of the last resort to prevent spilled oil from reaching ecologically sensitive habitats and recreational activities in coastal areas. While booms, skimmers and dispersants may be very expensive and difficult to deploy, ISB is relatively inexpensive, making it attractive to oil spill responders. ISB can be applied in marine, coastal, freshwater, arctic and terrestrial environment. Factors affecting burn efficiency include water density, type of oil, slick thickness, degree of emulsification and weathering, flame coverage, wind speed and wave action. Although ISB has been very successful in removing spilled oil from polluted environment, there are great concerns about the transport and fate of emissions and residues from the burned oil, on the environment, biodiversity and public health. Potential air pollutants from oil burning include particulate matter, nitrogen oxide, sulphur dioxide, carbon monoxide, carbon dioxide, volatile organic compounds, and mixtures of various polycyclic aromatic hydrocarbons. Many developing nations lack the legal and regulatory frameworks, the contingency planning process and human resources to monitor the implementation of ISB in the oil and gas industry, making the practice very complicated and of imminent danger to society. There is also need to develop alternative measures to ISB in order to mitigate the effects on the environment and human population.
Global Warming Issues, Challenges & Vulnerable Africa – Cleaner Energy Possibilities, Emission Reduction Analysis and Mitigation Strategies
Authors: Umeh Ebuka , Onyekperem Cyprian
Published: July 2019

This paper is intended to tackle and treat the subject of global warming which includes its components, current issues, trends and challenges to enable us to add our own mitigation measures to support the global efforts on its reduction. The caustic effects would be analyzed using environmental data gotten from Environmental Impact Assessment (EIA) studies and Environmental Evaluation Report (EER) from various field locations in the oil production fields in the Niger Delta region of Nigeria. Analysis of the various cleaner energy alternatives other than fossil fuels would be done, with individual challenges of these alternatives been highlighted, from which a projection for the zone under study would be done using graphs and data plotted in Excel. Mitigation strategies has been suggested and backed with adequate recommendations that are gotten from sample opinions from experts in environmental matters in the oil and gas industry.
Dynamic Risk Assessment – A MacGyverism to Worksite Incidents
Authors: Umeh Ebuka
Published: July 2019

The industry is in constant research with consistent efforts to ensure that the no/less incidents occur during the course of operations. Notable and popular slogans/rules have been adopted among engineering and oil & gas organizations over the years in the industry to intimate the need for safe activities to be performed among staff. Slogans like Goal Zero, Golden Rule dictum, "Safe…Yes we can", Life Saving Rules, "No Wahala…Take 5" and many others have been used in recent times to inculcate the culture of safety and situational awareness in the mind of the work force. Tools like check cards, stickers, safety IDs and banners are also quick reminders of the environment being operated on.

However while all these tools are fairly efficient, the need for proper risk assessment cannot be over-emphasized at all times before a job to be done can be certified safe. Worksite Tools like toolbox talk, last minute risk assessment (LMRA), Job Hazard Analysis (JHA) and post job debrief are veritable towards achieving this goal. But while risk assessment before the job commences is important, of equivalent or even much importance is the one conducted during the job and this is called dynamic risk assessment.

This paper presents an approach and exposition of the risk assessment plan in the operations level in the oil and gas industry. It also discussed on the methods to be deployed a successful risk assessment and buttress further on static and dynamic risk assessment as it concerns operations in a gas process plant. A new conceptual risk assessment model has been developed. A case study was treated from Atabala Plant which is a gas processing facility in the south southern Nigeria.
Reservoir Navigation in Njaba Field – Challenges, Procedure and Results
Authors: Ndokwu C. , Amadi K. , Toyobo O. , Okowi V. , Ajisafe I. , Inenemo A.
Published: July 2019

Due to the low oil price, Exploration and Production (E&P) companies are driven to reduce the cost per barrel of oil equivalent (BOE). The application of reservoir navigation services, in the placement of high angle and horizontal (HAHZ) wells in the sweet spot of reservoirs, has aided in meeting this economic need of the E&P, while also improving hydrocarbon recovery.

Reservoir navigation services (RNS) can be regarded as another tool for improving the odds of success while drilling of HAHZ wells. This service involves the integration of real-time data (deep-reading azimuthal resistivity, gamma-ray, density image, resistivity image logs, near bit inclination and a fit for purpose rotary steerable system) to accurately position the well-bore relative to specific subsurface targets, while remaining within the constraints of the drilling and completion program. RNS also require a software package capable of pre-well modeling, displaying the acquired real-time data and interactively adapting the model to the real-time data.

Geosteering in Njaba field involved a comprehensive pre-well planning, discussions, documentation and management approved decision-tree. Using three wells for this study, this paper describes the challenges, procedures and results of geosteering in Njaba Field located on-shore Niger-Delta. From different entry points, wells NJX1, NJX2, and NJX3 were planned to drain the same reservoir and optimize hydrocarbon recovery within the reservoir. Some of the challenges encountered includes geosteering the wellbore above a pre-determined production TVD hardline while simultaneously avoiding drilling into an overlying undulating shale cap rock, vertical seismic uncertainty and undulating formation boundaries.
The Effect of Monovalent and Divalent Ions on Biodegradable Polymers in Enhanced Oil Recovery
Authors: Eiroboyi I. , Ikiensikimama S. S. , Oriji B. A. , Okoye I. P.
Published: July 2019

The stability of polymers used in enhanced oil recovery especially in polymer flooding is largely based on their ability to withstand challenging reservoir conditions such as the effect of high salinity and high temperature. Polymers like Hydrolysed Polyacrylamide (HPAM) and its derivatives lose their viscosity when subjected to high salinity conditions due to the screening of the ions of the polymer backbone chain. HPAM is not only sensitive to salinity and temperature but also very susceptible to shear degradation. Research show that Xanthan gum; a commercial biopolymer used mostly in polymer flooding show more tolerance to shear degradation and even better stability to salinity and temperature than HPAM but not frequently used due to its high cost.

The work is centered on the study of stability of some selected low cost biopolymers like Guar gum, Locust bean gum, Gum Arabic as well as the commercial Xanthan gum. This study captures the effect of monovalent and divalent ions on the polymers in order to establish their degree of stability and the impact of these ions with respect to varying salinity conditions. The rheological performance of these polymers were analysed using both NaCl and CaCl under both medium and high saline conditions which are similar to reservoir conditions. The results show that all polymers show appreciable resistance and stability when compared to Xanthan gum especially Locust bean gum in the presence of monovalent ions, Gum Arabic displayed the least tolerance to the ions. Although, the presence of divalent ions had more impact than the monovalent ions on all polymers' stability, however, higher concentrations of the polymers resulted in more resistance to the presence of these ions.
Towards Information Transparency: Current Posture and Advocacy for Open Data Systems for Efficiency, Equity and Justice – The Nigerian Oil and Gas Experience
Authors: Ante M. A. , Ante A. E.
Published: July 2019

Transparency in information is one of the most important undertaking that the government in collaboration with oil and gas stakeholders can offer to the public. Open, and therefore, accessible, nonproprietary data in the current information age is a tool for improved governance, transparency and innovation.

The oil and gas industry is a huge data generator through its daily operations, it is a leader and in fact, a home to big data. From existing development assets, to supply chains, customer relations etc, data provides a competitive advantage for organizational growth and management. Beyond the strategic opportunities that big data provides within the industry, is the enormous capabilities that big data through open data initiatives can have on company-community relations.

In this paper, we examine the various acts and legislations governing oil and gas industry operations and their position on data transparency. Our examination sheds light on current positions of the tripartite of law, policy and practice and the demonstrated gaps between this tripartite. In addition to the legal analysis, we also examine the issue of open data through the petroleum engineering prism. The benefits and significant impact a movement in open data will deliver to the industry are also examined which include but are not limited to: addressing public concerns and increasing community workforce participation and protection of oil and non-oil natural resources.

Finally, because discussion on open data is incomplete without the necessary data literacy skills needed to utilize, analyze and draw meaningful conclusions from data, we examine how best we can increase these skills within the community to bridge the information divide.

As we enter 20 years of steady democracy and political process in Nigeria, open data will certainly disband doubts and fake news in our energy conversations as it will provide a level playing field for all parties. Public discourse will be more focused on facts and lead to improved and sound decision making.
Petrophysical Evaluation of the Reservoir in the K - Field, Offshore Ghana
Authors: Anumah Prosper , Mohammed Shaibu , Sarkodie-Kyeremeh Justice , Aggrey Wilberforce Nkrumah , Morgan Anthony
Published: July 2019

Reliable assessment of the petrophysical properties of hydrocarbon-bearing reservoirs is essential for the estimation of hydrocarbon reserves, identification of good production zones, and assessing the need for hydro-fracturing jobs. The K-Field although discovered in the 1970s is yet to be developed.

In this study, well logs from the wells drilled in this field were analysed with the primary objective of determining the petrophysical properties of the reservoir zones using various estimation models. From the log readings, the reservoir sands containing hydrocarbons in the field are found to be located at the Mid Turonian (90Ma)-Intra Upper Albian (96.5Ma) and Intra Upper Albian (98Ma). The porosity was determined using the density log and crossplots. Archie and Simandoux correlations were utilized in the determination of the water saturation. Permeability was estimated using Timur, Tixer and Coates correlations.

The findings after the petrophysical evaluation indicate that the wells entered formations with good reservoir quality in terms of porosity, which ranges from 16.12% to 20.97%. In relation to hydrocarbon saturation and permeability, two of the wells gave better results suggesting that they were drilled through the productive part of the reservoir. Nonetheless, the average permeability of the reservoir is estimated to be very low. This suggests that in the field development planning, well stimulation methods should be incorporated to aid the ability of the reservoir rocks to transmit fluids into the production wells.
Maximising Oil Recovery in Mature Water Floods Using Automated Pattern Flood Management
Authors: Okon Edet Ita , Adetuberu Joseph Adeoluwa , Appah Dulu
Published: July 2019

One of the most significant challenges for extending production life in mature waterflood fields is high water production. Couple with high reservoir heterogeneity, extensive layering and faulting, these fields often developed irregular flood patterns after decades of production which compounded the challenge to optimizing recovery from these fields. The severity of this problem can be seen in the Niger Delta oil fields where there are several matured fields that are producing at high water cut after many years of water flooding. The main objective of this study is to maximize oil recovery from a matured waterflood oil field while reducing the water cut. To achieve this objective, simulation studies were conducted on two cases scenarios. The first case was modelling and running waterflood simulation studied without applying pattern flood management (No PFM) while the second case scenario was done by exploring an automated pattern flood management (PFM). This was done with the aid of Petrel E&P software platform and ECLIPSE FrontSim to efficiently optimize the rate of water allocated to individual injectors. Using data from one of the oil fields operating in the Niger Delta, their performances were compared. The PFM gave the best result with a cumulative oil production of 30,727,470 STB when compared with the case of No PFM which gave a cumulative oil production of 26,968,224 STB (about 12% increase in oil recovery). The PFM water cut was 16% when compared with the case of No PFM which gave a water cut of 47% (about 63% reduction in water production). Hence, The PFM approach has made it possible to reduce water injection in more than 30% of the injectors while more than 62% of the producers experienced increase production and reduced water cut. The productivity increased upon automation of the workflow will enable engineers to identify the optimal injection allocation factors. It will also help engineers to understand and produce from the reservoir at an optimized decline rate and ensure the increase in ultimate recovery.
Cassandra: A Model and Simulator Developed for Critical Drawdown Estimation in Unconsolidated Reservoirs
Authors: Ehihamen Precious
Published: July 2019

Without doubt, one of the most frequently occurring problems in production facilities with dire consequences is sand production. Sand production refers to the continuous flow of formation grains alongside reservoir fluids during production. It is a problem that is more associated with unconsolidated reservoirs such as those present in the Niger Delta. Some of the problems associated with sand production include stabilization of emulsion, vessel blockage, erosion of vessels and reduction in separation effectiveness (Bibobra et al, 2015) all of which have economic consequences, thus, can render companies bankrupt.

In a bid to avoid the aforementioned problems, many sand control measures have been developed, however, with increase in effectiveness in handling sand comes a corresponding increase in cost, hence, necessitating a feasibility study to ascertain their viability. Many authors have developed mathematical models useful in predicting sand production in reservoirs. These models have proved to be useful tools in sand control viability studies. Geomechanical parameters like principal stresses have been useful in these models. However, many of these models developed have turned out complex, requiring difficult-to-obtain parameters or having low level of accuracy when compared to observed field data. In this paper, a mathematical model was developed by modifying the work of Oluyemi and Oyeneyin (2010) who developed a simple mechanistic model requiring few and easy-to-obtain input parameters. A simple simulator, named Cassandra, was then designed using Python Programming Language so as to aid the estimation process.

After validation with field data from different reservoirs, it was found that Cassandra gave results very close to observed field data, in fact, it only possesses about 8% absolute error. The model also performed excellently when compared to existing models. This software, thus, proves to be a valuable tool in any sand production analysis.
Reducing Drilling Operations Cost Through Rental Inventory Management - A Case Study
Authors: Numbere Otokini , Aigbedion Prince , Okoli Ugo' , Okubor Eleanor , Olugbesan Babatunde , Ntiwunka Greg
Published: July 2019

In a regime of volatile oil prices, it has become increasingly important to plan and deliver cost effective wells safely. Typically, this is achieved by optimizing technical details in planning and execution phase; however, an often-overlooked area of optimization is the management of rental tool inventory and the associated logistics. This area is usually subject to cost overruns due to insufficient tracking of equipment from mobilization through its use at the rigsite, resulting in late demobilization and incurring of additional cost by operators.

To completely eliminate these unwanted costs, a web/intranet based, equipment tracking solution which interfaced with the existing enterprise resource planning (ERP) platform (for contracting and procurement information) was designed and implemented by Addax Petroleum Nigeria to track and monitor the movement of rented equipment between service providers, logistics base and operations base. It ensured the effective tracking of rented equipment upon mobilization up till demobilization; this helped to prevent cost overruns for rented equipment during the drilling campaign. Daily reports and notifications were also provided to all key personnel on rented equipment status and it ensured a collaborative workspace for drilling team members to manage rented equipment movement internally.

The rentals inventory tracking application (RITA™) software was deployed during a six-month drilling campaign in 2017/2018. It provided comprehensive tracking for equipment mobilized to the rig, eliminating cost overruns on rental equipment throughout the project and cost savings of circa $1,000,000 during the six-month drilling campaign.
Assessment of Reservoir Properties using Applied Rock Physics & Seismic Inversion for Near-Field Exploration in a Niger Delta Field
Authors: Adesun Julius , Olajide Olanike , Ekesiobi Chidi , Ogunjobi Abidoun , Ishola Kehinde
Published: July 2019

A quantitative seismic interpretation (QSI) approach in assessing reservoir properties of a near-field exploration discovery is presented.

This approach demonstrates the integration of rock physics model and seismic inversion to determine the lateral extent of the reservoir complex, improve the understanding of geometry and connectivity of the reservoir sands encountered in this field; and improve confidence in estimates of the resource base.

An integrated interpretation approach that incorporates seismic and well log data sets, together with available relevant reports is adopted to reduce interpretation risk inherent with the study location. The hydrocarbon bearing reservoir sands were characterized, based on their elastic rock properties responses, to predict reservoir parameters for reservoir architectural delineation from seismic data volume. The results provide insight to address subsurface uncertainties associated with reservoir connectivity, and future infill well count determination for production optimization and possible reserves addition.
Paper Hedging Against Cyclical Crude Oil Price Fluctuations: Cost Optimization Initiatives for the Nigerian Oil & Gas Industry
Authors: Ugolo Jerry , Fagbami Debo , Iwegbu Mike
Published: July 2019

This paper discusses the effect of crude oil price fluctuation on the personnel, projects and finances of oil & gas exploration and producing companies, as well as, the cost optimization efforts carried out during the era of lowcrude oil price. Following investigation and historical data, it is evident that crude oil price fluctuation is cyclical in nature. To make their product available for sale, oil & gas organizations, at the peak of the crude oil cycle engage in high operating-cost systems. With drastic fall in the price of the product, as experienced between July 2014 and February 2015, such organizations were faced with the challenge of continuing production at a non-profitable cost.

Crude oil price fall, have always had a big negative impact on the personnel, projects and operations of organizations in the Nigerian oil and gas industry. For personnel, the most prevalent impact was the loss of jobs, for company operations it was the reduction in revenue (income) for the companies and for projects it was the delay or cancellation of projects earlier considered profitable. These losses or delay of projects led to reduction in product portfolio and/or divestments for the organizations involved.

For the Nigerian oil and gas companies to adapt to the economic changes occasioned by the change in price, several measures have been proposed which include individual companies initiating and utilizing procedures that ensure good costing of projects, benchmarking of relevant prices and promoting good costing practices and proper management of balance sheet and adhering strongly to sustainable OPEX and CAPEX levels, to ensure opportunities are identified and utilized.

The researchers asserts that crude oil price fall with its attendant negative impact could be scientifically explained. A quantitative research methodology has been applied in the study of this topic. Using online survey, information has been gathered from respondents from six different oil and gas companies indicating their demography, individual experience, companies experience and project experience during the last crude oil price fall (2014 -2017). Secondary data obtained from historical records helped to show the influence of crude price slump on the financial health status of oil and gas exploration and producing companies. The data also helped to confirm the primary data received in the online survey.
Waterflood Management in Spring Field
Authors: Kuku Abimbola , Omotayo-Johnson Mobolaji , Achinivu Ochi , Awotiku Oluwabiyi , Oyegwa Akomeno
Published: July 2019

Spring Field was discovered in 1963 and started production in 1965. Waterflooding began in 1999 in one reservoir and has subsequently expanded to nine reservoirs to date. Waterflooding in the Spring Field is basically a peripheral water injection system with the use of brackish water as injection water. Waterflooding in Spring Field has been instrumental in "arresting" base decline, sustaining and re-pressurization of depleted reservoirs. There are currently 29 active producing reservoirs in the Spring Field with waterflooded reservoirs accounting for ~ 63% of current oil Production and ~ 52% of the estimated ultimate recovery (EUR).

The management of waterflood systems can most often be quite challenging with Spring Field not being an exception. Waterflood challenges observed in Spring Field include both surface and subsurface issues such as non- uniform volumetric sweep due to complex reservoir architecture (Compartmentalized/ Multi-lobed Reservoirs), long fill-up time due to late startup of water injection, unbalanced Injectivity, out of zone injection, injection pumps reliability to mention a few. Managing and resolving these issues would therefore require a systematic and logical structured approach to ascertain the "health" of the Waterflood system in place with the overall objective of improving its efficiency, hence the purpose for this paper.

This paper focuses on the use of the Surveillance, Analysis and Optimization (SA&O) workflow processes in the management of the water flood system currently in place in the Spring Field. The paper also highlights examples where this workflow process has helped in identifying gaps and optimization opportunities in the Spring Field. The Surveillance, Analysis and Optimization process include the following: ➢Surveillance- Acquisition of necessary data from multiple sources.➢Analysis- Review/ Interpretation of acquired data using various diagnostic tools. For ease of Analysis and Reviews, this element is subdivided into three distinct categories:● Health Check Category● Predictive Category● Problem Identification Category➢Optimization- Recommended corrective actions and efforts carried out to improve Waterflood efficiency based on observations from various analysis.
Artificial Neural Network for Prediction of Hydrate Formation Temperature
Authors: Olabisi Odutola Toyin , Atubokiki Ajienka Joseph , Babawale Ojedapo
Published: July 2019

Gas hydrate deposition is one of the major Flow Assurance problems in petroleum production in the offshore environment. Therefore, is important to accurately predict hydrate formation conditions and avoid these conditions or propose a hydrate management plan. This study compares the effectiveness of Artificial Neural Network (ANN) for predicting hydrate formation temperature to the effectiveness of other hydrate temperature prediction correlations such as: Towler and Mokhtab correlation, Hammerschmidt correlation and Bahadori and Vuthalaru correlation. The ANN was trained using 459 hydrate formation experimental data points from Katz chart and Wilcox et al chart. Pressure (P) and specific gravity (ϒ) were chosen as the inputs in the 4-layer network while temperature was the output. The data points were for gases of specific gravity of 0.5539, 0.6, 0.7, 0.8, 0.9 and 1.0. The experimental pressures considered were from 49 psia to 4000 psia. The Neural Network was built using an excel add-in tool, NEUROXL. ANN accurately predicted the experimental hydrate formation temperature with the regression coefficient greater than 0.98 for the different specific gravities considered. Moreso, the error analysis shows ANN performed better than Towler and Mokhtab correlation, Hammerschmidt correlation and Bahadori and Vuthalaru correlation because it had the least Mean Absolute percentage error, MAPE (3.5) compared to the other correlations. ANN is a viable tool for hydrate prediction and the current model can be improved upon by including more experimental data in the ANN.
Geobody Interpretation and Its Application for Field Development
Authors: Olaniyi Adenaiye , Miguel Mora-Glukstad I. , Anindya Das , Kefe Amrasa
Published: July 2019

Geobody identification via Spectral Decomposition has been used to optimize the development of a reservoir for a green field (Nime – not a real name) in the shallow offshore Niger Delta.

The target reservoir (NM1 – not real name) is covered by a 3D seismic data that was acquired and processed using Post Stack Time Migration technique in the late nineties. Six exploration and appraisal wells have been drilled through the reservoir to date. Stratigraphically, the reservoir is approximately a 250- feet thick high net-to-gross (0.98 – 1), high porosity (0.26 – 0.28) sandstone interpreted to be stacked channel and shoreface sediments that were deposited in marginal marine environment.

Given the high net-to-gross and porosity of the reservoir and absence of any intra-reservoir fault that may compartmentalize the reservoir, the reservoir is deemed laterally continuous and connected. However, fluid contact values derived from reliable combination of gamma ray, resistivity, neutron and density logs from the wells indicate a difference of 25 feet for the oil water contact (OWC) in the reservoir. To fully understand the contrasting information viz 25ft OWC difference in a highly sandy and ‘connected’ reservoir, spectral decomposition volume attribute was generated from the 3D seismic data and analyzed to determine the reservoir architecture.

The spectral decomposition workflow applied involved two basic steps: i) Spectral analyser – to determine dominant frequencies in the 3D seismic volume; and ii) Spectral decomposition – creating 3D volumes for the dominant frequencies and analyzing them with the aim of identifying geobodies (channels) and defining the reservoir architecture.

Prior to carrying out the Spectral Analyser, the 3D seismic cube should be ‘cropped’ to the required area of interest (AOI) to reduce computer memory required to run the algorithm. It is also advised to run any post-processing seismic workflow (e.g. VanGogh) that will increase signal to noise ratio before spectral decomposition.

This paper presents the details of the Spectral Decomposition workflow which can be applied for identification of geobodies and how its result was used to optimally plan development wells in the target reservoir to mitigate an unlikely compartmentalization of the reservoir.
Safety and Economic Assessment of the Voltaian Basin Project
Authors: Fuah E. B. , Otoo F. N. , Anthony W.
Published: July 2019

The Voltaian basin, Ghana's largest inland basin is the least explored of the sedimentary basins in Ghana. Based on past reconnaissance surveys, albeit limited survey data, the basin is believed to have prospects of hydrocarbon reserves. The government has therefore renewed interest in the Voltaian Basin Project (VBP) to prepare and promote the basin to allow hydrocarbon exploitation activities. Ghana National Petroleum Corporation (GNPC), has been tasked to undertake this project. This paper undertook a safety assessment of the VBP and post VBP, and also examined its economic impact on the Ghanaian economy using standard risk management techniques and economic modelling respectively.

It was deduced that a combination of high to low levels of risk exist in all phases of the project. Out of 64 hazards identified with the VBP and post VBP, three (3) were found to be of high risk, fifty-one (51) of medium risk and ten (10) of low risk. These risks range from gas leakage, through cement plug failure to slips, trips and falls. However, with appropriate mitigation measures such as routine inspection, routine maintenance and repairs, organizing periodic training programs and ensuring a robust Safety Management System, these risks could be reduced to the barest minimum, if not eliminated. The project is therefore a safe endeavour.

In the event of commercial discovery, based on reliable data and informed estimations, the project was observed to accrue net earnings based on net present value for all stakeholders in the sums of at least $18.8 billion, $2.5 billion and $23.8 billion for government, GNPC and International Oil Companies respectively after ten (10) years of production.

The project, if successful, would contribute immensely to the development of the Ghanaian economy. It is expected to replenish the country's declining reserves, provide a comparatively cheaper means of hydrocarbon exploitation, help build the capacity of the national oil company for operatorship in Exploration and Production operations and enhance Ghana's energy supply, bridging the demand gap.
Creating Value Through Integrated Reservoir Study in Mature Asset via Reservoir Uncertainty Characterization: A Case Study from the Niger Delta Field A05 Reservoir
Authors: Jaja Adagogo J. , Okani Nnamdi , Eme Vincent , Ricardos Ricardo Combella , GOM Chevron , Silpngarmlers Lynn
Published: July 2019

In the Early phases of field development, the drilled hydrocarbon appraisal wells may not have been sufficient to define rock properties, fluid typing and contacts. It's very important to define the range of uncertainty in such fields. This is because as the field matures other dynamic data will become available to validate these probable volumes.

The ideal development scenario provides the practitioner with a full suite of data defining the reservoir geometries, reservoir properties, fluid properties etc. to make subsurface decisions. However, in most cases, operational realities will deny the reservoir practitioner this full suite of data.

One practical convention that is used to resolve this data paucity challenge is to evaluate and report the lowest possible volume, if this low case is economic the project will be economic with potential for more upside outcomes. However, a challenge that can arise with this is that after several iterations the low case can become the only case. A better practice is to characterize uncertainty of reservoir parameters during the early stages of field development and carry out the full range outcomes through the field's life. These ranges will then be validated as the field matures.

This paper demonstrates a case in the Niger Delta field A05 reservoir were dynamic simulation model was used to narrow the uncertainty range on the GOC. Proper identification and characterization of the GOC uncertainties helped for the estimate of a range of STOOIP used for dynamic simulation model. Though no static dataset was available to reduce this uncertainty on the GOC, during dynamic simulation, the high-case oil in-place volume was found to be the best match to historical production data with the integration of another reservoir, Delta A12, in one dynamic simulation model. Both reservoirs communicate through the aquifer, separated by a saddle. This then proved up additional volumes in the reservoir, identified previously overlooked reserves and allowed the asset team to propose an extra infill well opportunity than what was previously planned. This new understanding of the A05 reservoir increased the oil estimated ultimate recovery (EUR) by 4.6 MMSTBO.
Performance Assessment and Economic Analysis of Blended Class G Cement With Local Cement for Oil Well Cementing Operations: A Case Study of Ghana
Authors: Amorin Richard , Broni-Bediako Eric , Westkinn Collins , Appau Prince Opoku
Published: July 2019

Good cementing job practices are required for an efficient advancement in drilling and production operations. Most drilled oil and gas wells in Ghana employ the use of class G cement in its cementing operations. This class G cement is imported, scarcely available and relatively more expensive compared to other forms of cements. It also does not promote the local content and local participation policy of the country in the oil and gas sector. This has therefore necessitated the need to research into available local cements (easily available and relatively inexpensive) as an alternative to serve the same purpose as the imported class G cement. This research therefore assesses the performance of class G cement blended with local cement at different ratios in an attempt to reducing the overdependence of the class G cement while considering the technical requirements and economic implications. All the blended samples met the minimum API compressive strength requirement of 1500 psi when cured for 8 hours at 140 °F. Though, free fluid values increased with increasing amount of local cement ratio, all values recorded were below the maximum field requirement value of 5.9%. The blended samples exhibited the ability to be pumpable, recording plastic viscosity less than the maximum recommended value of 100 centipoise (cP). It was therefore established that the use of blended samples (local and Class G) for oil well cementing operations in Ghana would save the industry from 19.57% to 78.28% of money over the use of class G cement only. Considering the performance and economic benefits of the blended cement over the class G cement only at the test conditions, it is highly recommended that, the industry adopts the blending of class G cement with the local cement in their cementing operations to boost the local economy as well as to reducing their cementing operation cost.
Evaluation of Cuttings Transport in Well Annulus Using Power Law Model
Authors: Menegbo Edward K. , Charles Eme , Dosunmu Adewale
Published: July 2019

The efficiency of cuttings transport is very important factor for a good drilling operation program. The transportation of these cuttings through the annulus is a complex problem that is affected by many parameters. For effective cuttings transport prediction, it will require that all these parameters be considered simultaneously. Predictions of pressure losses and cuttings transportation through the annulus are very complex during drilling operation due to the combination of interacting drilling parameters. Success during drilling program is due to efficiently cleaned hole. For better understanding of the effects of some of these parameters that affect cutting transportation, the power law of non-Newtonian viscosity model was adopted to establish the mathematical model of the cutting transport process in the well annulus. Some of the hole-cleaning challenges focused are: the absence of the basic data needed to fully evaluate present field practices and current concepts on drill cutting transport, the combined effect of operational parameters and drilling fluid properties, the effect of operational parameters and cutting properties and what is the effect of rheology model on cutting transport simulation. Poor hole-cleaning during drilling can lead to a lot of bore hole issues which has a negative effects. The overall effect is increase in drilling time and drilling cost. The proposed tool allows more precise prediction of cuttings transport property in the whole range of the well. In this paper, the effects of annular fluid velocity, transport ratio, size and density of cuttings are investigated. The results obtained showed that the most important factors controlling cutting transport are annular velocity and the fluid rheological properties. From the simulation result, it can be observed that an optimum transport ratio was obtained at 1.42m/s. The transport ratio increases rapidly with velocity but then begins to level out or increase more slowly in the velocity range of 1.42 to 1.62 m/s. We can also deduce from the result that cuttings velocity increases with the flow rate; but this increment does not follow a linear behaviour.
Rheological Properties of Terminalia Mantaly Exudate as Drilling Mud Additive
Authors: Inemugha Olanari , Chukwuma Franklin , Akaranta Onyewuchi , Ajienka Joseph A.
Published: July 2019

Polymers are known for controlling fluid loss and modifying rheology in drilling muds through polymer chain entanglement and polymer-solvent interactions. Natural polymers have been used in the formulation of drilling muds, mainly due to their high molecular weight and eco-friendliness but they have limitations in controlling fluid loss, modifying viscosity or forming good gel strength in saline and thermal environments. This study reports laboratory evaluation of Terminalia mantaly exudates as viscosifier in drilling mud formulations. The effects of polymer concentrations, temperature, pH and salinity on the rheological properties of this novel biopolymer were investigated. Results obtained show that as polymer concentration increases (0.5% – 2.5%w/v), the rheological properties (apparent viscosity, plastic viscosity and yield point) of the biopolymer increased. At the polymer concentrations investigated, an increase in temperature (80°F-150°F) results in a slight decrease in the rheological properties of the polymer. At 2%w/v polymer concentration, an increase in salinity results in a slight decrease in its rheological properties, while at 1.5%w/v polymer concentration, an increase in pH (4-10) shows no significant change in the rheological properties. The shear stress increases with increase in shear rate and obeys the Bingham plastic model. The results obtained show that the polymer has a good alkaline resistance at pH above 7 and stable rheological properties at increased salinity and temperature. This has been attributed to the stable repulsive forces of the negatively charged polyelectrolyte of the polymer as salinity increases. From the results obtained in this study, Terminalia mantaly exudate can be a substitute for conventional natural polymers in water-based drilling muds.
Key Success Factors and Challenges of Gas Injection in a Deep Offshore Turbidite Environment – Deepwater Akpo Field Example
Authors: Oukmal Jed , Biu Victor , Usman Musa
Published: July 2019

Gas injection is used as an improved recovery mechanism to provide reservoir pressure maintenance, oil swelling and sweeping. This mechanism offers a high microscopic recovery comparing to water injection thanks to a lower residual oil saturation to gas. However, its macroscopic recovery tends in general to be smaller due to a lower sweep efficiency - a direct consequence of high gas to oil mobility ratio. The case of Akpo Z represents a success story where gas injection led to a significant increase in the condensate ultimate recovery higher than 70%, as a result of the combination of both high microscopic and macroscopic recoveries. Akpo Z is a light condensate-bearing turbidite reservoir deep offshore Nigeria and has been developed using two gas injectors located at the crest of the structure with four oil producers at the flanks. The key success factors of gas injection in Akpo Z are linked both to a favorable subsurface environment, in particular, a large structure, good horizontal connectivity and a near critical light fluid, but also to appropriate reservoir development choices. These elements are detailed in this paper. This paper also shows the challenges linked to daily reservoir management and monitoring from an operator point of view, in particular, the impact of gas injection availability on condensate production shortfalls and the uncertainties linked to gas production and injection metering. Throughout the field life, several monitoring tools such as Intelligent Well Completion (IWC) and 4D seismic have been leveraged to take appropriate reservoir management decisions that led to a delay in gas and water breakthrough and sustain field condensate potential.
Divergent View on the Use of Interpolation Techniques in Reservoir Analysis
Authors: Ezenworo Ebuka , Achumba Gabriel , Adenuga Kazeem
Published: July 2019

The most common methods of interpolation are direct, lagrange, newton divided difference, and spline. Each of these techniques has first, second, and third order approximating polynomials that can be used anytime the need for interpolation arises in mathematical analysis. Of all the methods outlined above, the first order approximating polynomials of these interpolation techniques have found great use because of the ease of application. The fact that these polynomials estimate approximate values calls for the need to check the most accurate interpolation method. Accuracy in reservoir modelling and analysis is of great importance to the petroleum industry because business decisions are taken from the outcome of such analysis. Most of these analyses depend on the accuracy of interpolation been employed.

In this paper, some basic PVT parameters were analyzed with both large and few data points. Few data points were used in order to replicate real life scenario since most of the PVT parameters come with few data point after laboratory experiments. For the large data points, all the interpolating techniques irrespective of the order of their approximating polynomials gave a good result but with few data points, different results were obtained. From the results, it was observed that for PVT interpolations, spline third order approximating polynomial performed better than the rest with few data points.
Well Placement Optimization Using Simulated Annealing and Genetic Algorithm
Authors: Tukur Aisha Diggi , Nzerem Petrus , Nsan Nhoyidi , Okafor Ikechukwu Stanley , Gimba Abdullahi , Ogolo Oghenerume , Oluwaseun Alonge , Andrew Okafor
Published: July 2019

The general success ratio of wells drilled lies at 1:4, which highlights the difficulty in properly ascertaining sweetspots. well placement location selection is one of the most important processes to ensure optimal recovery of hydrocarbons. Conventionally, a subjective decision is based on the visualization of the HUPHISO (a product of net-to-gross, porosity and oil saturation) map. While this approach identifies regions of high HUPHISO regarded as sweetspots in the reservoir; it lacks consideration for neighbouring regions of the sweetspot. This sometimes lead to placement of wells in a sweetspot but near an adjoining aquifer; giving rise to early water breakthrough - low hydrocarbon recovery. Recently, heuristic optimization techniques. Genetic algorithm (GA) and simulated annealing (SA) has received attention as methods of selection of well-placement locations. This project developed and implemented GA and SA well-placement algorithms and compared the reservoir performance outputs to that of conventional method. Firstly, a reservoir performance model was built using a reservoir flow simulator. In the base case, the wells were placed based on a subjective selection of gridblocks upon the visualization of the HUPHISO map. Thereafter, JAVA routines of GA and SA well-placement algorithms were developed. The numeric data (ASCII format) underlying the map were then exported to the routines.

Finally, the performance model was updated with new well locations as selected based on the GA and SA-based approach and the results were compared to the base case. The Comparison of the results showed that both GA and SA-based approach resulted to an increased recovery and time before water breakthrough.
Use of Radial Basis Function Networks for Efficient Well Production Allocation
Authors: Zubarev Maxim , Zubarev Denis
Published: July 2019

Well production allocation is the cornerstone of reservoir surveillance and sound reservoir management. The apparent simplicity of the allocation process often results in an underestimation of its critical importance. However, the accuracy of the production rates allocation has an overwhelming impact on the company's ability to use sound data and perform model-driven analytics. As a result, the reliability of production forecasts, reserves estimates, and production system optimization efforts are affected by the selected allocation approach.

A common approach to well production allocation is based on the use of well tests closest in time to the point of interest. It assumes stable operating conditions and gradual changes in fractions of produced fluids. These assumptions rarely reflect reality and therefore lead to large allocation errors. Use of more sophisticated solutions, such as data-driven and model-driven integrated well-reservoir tools pose different challenges due to the constant need for time-consuming updates.

In this paper, we present a quick and efficient approach for production data allocation based on single layer Radial Basis Function Network - a variation of Artificial Neural Network. The procedure takes advantage of full well test dataset and can be effectively used in real time. We show that this approach does not suffer from the limitations of the more common approaches while delivering improved results.