Julius U Akpabio | University of Uyo, Uyo, Nigeria (original) (raw)

Papers by Julius U Akpabio

Lost circulation of drilling fluid results in higher operational expenses which makes it imperati... more Lost circulation of drilling fluid results in higher operational expenses which makes it imperative to design the fluid, such that minimal invasion of the fluid occurs in the formation. To achieve this, Lost Circulation Materials (LCM) are required which is expected to seal the fractures hence, the performance of Oyster Sea-shells (Crassostrea Virginica) as a lost circulation material is being investigated knowing that it is rich in Calcium Carbonate. Sea shells were prepared, pulverized and sieved to obtain fine grain particles which were analyzed in the laboratory for various properties. A fractured zone lost circulation test procedure was employed using a medium-sized fracture at 1000 psi. pressure drop and temperature of 80ºF. The tests were performed in triplicates and the rheological and gel strength results were obtained. It was seen that although the Oyster Sea shell is not a viscosifier, it passes API acceptability test for API acceptable range of Plastic Viscosity and Yie...

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In the petroleum industry, most active bottom-water drive reservoirs are completed strategically ... more In the petroleum industry, most active bottom-water drive reservoirs are completed strategically to handle produced water problems that may arise during the production of oil and gas. The water production may come in the form of a tongue, cone, cusp or a combination of all depending on the location, magnitude and direction of water movement. Thus, several attenuation methods have been developed to circumvent excessive water production as a result of water coning. Among these methods are selective water plugging, chemical shut-off, horizontal wells, downhole oil-water separation (DOWS) technology, etc. Recently, studies on DOWS technology have put forward two completions methods, namely, downhole water sink (DWS) and downhole water loop (DWL). Both completions approaches have mitigated water coning tendencies and improved oil recovery in bottom-water drive reservoirs. For DWS technology, the challenges of high cost of lifting fluids (i.e. oil and water) and handling huge volume of pr...

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More than 70% of oil-producing wells require some form of artificial lift to increase the flow of... more More than 70% of oil-producing wells require some form of artificial lift to increase the flow of fluids from subsurface to the surface when a reservoir no longer has sufficient energy to produce at economic rates. This situation has been observed in the Niger Delta oil wells over the past years and has caused the abandonment of reservoirs with a significant volume of hydrocarbon. Data from two oil wells that could not flow naturally to the surface have been obtained from an oil company operating in the Niger Delta. The arm of this study is to optimize the production of two oil wells using an artificial lift system. To increase production and extend the life of these wells, artificial lift projects were considered. This was done with the aid of Integrated Production Modelling (IPM) tool in Petroleum Expert suite. Two wells were simulated using the obtained data, and their production performances were evaluated. The well’s production outputs were optimized using artificial lift syste...

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British Journal of Applied Science & Technology, 2017

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British Journal of Applied Science & Technology, 2016

During production, drilling, completion, stimulation and work-over operations, the formation is e... more During production, drilling, completion, stimulation and work-over operations, the formation is exposed to several types of fluids which have high tendencies to impair and impact gas and oil productivity by reducing pore throat size and relative permeability. Therefore, it is desirable to accurately characterize filtration process during these operations. A mathematical model was developed describing the mechanism of formation damage in deviated wells. Rate of mud cake build up, cumulative filtrate volume and depth of invasion into the formation at different angles of inclination were determined. The model employed numerical approach rather than the conventional analytical method to solve the equations developed using the fully implicit discretization scheme. The effect of filtration on the angle of deviation was determined and this should help in planning and allocation of drilling time in order to reduce formation damage. Also the analysis shows the result of infiltration on cake thickness and filtrate volume at the early, middle and late time of permeation into the formation. The model was validated with the previous analytical model. Results showed that the previous conventional analytical models developed overestimate the formation damage when compared to the numerical model.

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This study reviews the performance of a three-phase coning model when simulated at different oil ... more This study reviews the performance of a three-phase coning model when simulated at different oil production rates, varying perforation intervals and permeability anisotropies. Data from the second comparative solution project which is a three-phase radial model with fifteen layers was used to run the sensitivities for production rates, perforation intervals and permeability anisotropies of the system. ECLIPSE 100 was used to simulate the different scenarios with the knowledge of the radial extent and fluid contacts of the system. The results obtained indicate that larger production rates increase the pressure gradient and consequently, improve the recovery efficiency of a reservoir. Longer perforation intervals produce more water while shorter perforation intervals produce less water; conversely, longer perforation intervals produce less gas and shorter perforation produce more gas. This indicates that smaller perforation intervals are likely to increase the water breakthrough time ...

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This work considers the Decline Curve Analysis (DCA) approach as a quick tool to estimate the gas... more This work considers the Decline Curve Analysis (DCA) approach as a quick tool to estimate the gas reservoir performance of field " ABC " in the Niger Delta region. The conventional Arps' models: Exponential, Harmonic and Hyperbolic, alongside with the Reciprocal and Quadratic models were used. Production data: gas production rate q and gas cumulative production G were obtained from 13 wells in the field " ABC ". Multivariate analyses were performed with the mentioned models to establish the decline constant (D i) and decline exponent (b); for hyperbolic model, of the field " ABC " in the Niger Delta region. A decline constant of 0.000064day-1 was obtained from all the models with exception of Reciprocal model with 0.00053day-1 for the gas field. Also, the decline exponent (b) obtained for Hyperbolic model was 0.9999. The statistical analysis: absolute error, standard deviation and coefficient of determination, of the fitted models used to ascertain the extent of their predicted values differ from the field test data results in Arps' models: Exponential-0.1150,

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The Exploration and Production (E and P) industry is one complex industry characteristically colo... more The Exploration and Production (E and P) industry is one complex industry characteristically coloured with boundless risk limits and occasioned by humongous capital requirements which more often than not are scarce in nature. This paper brings to the fore the various challenges that have confronted the E and P industry in Nigeria and the ways the industry has been affected. The top eleven challenges were isolated and discussed to find a common ground in order to bridge existing solution gaps. The choice of the top eleven challenges was in itself a challenge because of the wide spectrum from which to choose-from the very basic to the very complex. To achieve this, data from secondary sources were collected and analyzed using a descriptive approach. An organization of the final list shows that the challenges include four titles on oil facilities, three titles for each of uncertainty and the environment, two titles each of technology, people and government policy and one title for each of demand and insecurity. Two factors were observed to impact negatively on the industry namely; the uncertainty in getting at the oil itself and the uncertainty in the price of oil at a given time. In all, it is observed that revenue decline lies at the heart of the challenge map. However, for each challenge, existing approaches to solving them are presented and useful tips are suggested as to how to improve on the existing solutions. These suggestions are learnings tapped from other areas of the globe where they have proven successful. The ideas presented in this paper if utilized would help indigenous, service companies and the multinational companies involved in the oil & gas business in Nigeria to stay afloat especially at times that oil prices are plummeting.

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When reservoir pressure decreases in gas condensate reservoirs, there is a compositional change w... more When reservoir pressure decreases in gas condensate reservoirs, there is a compositional change which makes the system difficult to handle. This type of system requires an Equation of State (EOS) to ensure proper fluid characterization so that the Pressure Volume Temperature (PVT) behavior of the reservoir fluid can be well understood. High quality and accurate PVT data will help reservoir engineers to predict the behavior of reservoir fluids and facilitate simulation studies. The aim of this study is to determine what to do on reservoir fluid before carrying out reservoir modeling. PVT data were obtained from a reservoir fluid in the Niger Delta which was sampled following standard procedures. Then the laboratory experiments were critically examined to ensure accuracy, consistency and validity before PVT analysis. Finally, the results from the PVT experiments were imported into PVT software and subsequently in a reservoir simulator for simulation studies. These processes generate the EOS model for reservoir modeling of gas condensate reservoirs. 2 the consistencies of the data were ascertained and the composition added up to 100%. The pattern of the CCE/CVD comparison plot was observed to reflect that less liquid dropout was experienced later in the depletion process of the CVD experiment than in the CCE experiment. PVT validation checks help to confirm the Gas oil ratio of the system and the richness of the gas condensate fluid. It is imperative to obtain representative reservoir fluid samples and carry out reliable laboratory experiments to generate PVT data for fluid characterization. PVT fluid characterization and consistency checks will ensure that accurate results are obtained from reservoir simulation models leading to proper reservoir management. NOMENCLATURES A 1 = Slope of the Hoffman et al Plot A o = Intercept of the Hoffman et al plot BIP = Binary Interaction Parameter CCE = Constant Composition Expansion CVD = Constant Volume Depletion C f = Characteristic factor correlation EOS = Equation of State F = Total moles of Feed Fi = Hoffman Factor FVF = Formation Volume Factor F/V = Intercept of Mass Balance Plot GOR = Gas Oil Ratio K-Value = Y/X L = Total moles of separator Liquid L/V = Slope of Mass Balance Plot Mi = Molecular weight of Heptane plus Pc = Critical Pressure P D = Dew Point Pressure PR = Peng-Robinson PT = Patel and Teja Psc = Pressure at standard conditions PVT = Pressure Volume Temperature RK = Redlich Kwong SRK = Soave Redlich Kwong T = Separator Temperature Tb = Normal Boiling Temperature TBP = True Boiling Point Tc = Critical Temperature V = Total moles of separator Vapour VLE = Volume Liquid Equilibrium Xi = Moles fraction of component i in Liquid Yi = Mole fraction of component i in Vapour Zi = Mole fraction of component i in feed ZJ = Zudkevitch and Joffe i  = Specific Gravity

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Drilling is an important part of the oil industry and penetration rate must be enhanced to ensure... more Drilling is an important part of the oil industry and penetration rate must be enhanced to ensure speedy completion of drilling operation. Weight on bit, Rotary speed, drill bit type, formation characteristics and mud properties are the basic factors that affect the penetration rate of a bit. The focus of this work is on density which is a rheological property of the drilling fluid. Data obtained from eight wells were analyzed to ascertain the effects of Mud density on penetration rate.
Water and Oil based Muds were used to drill these wells which were in Sandstone/Shale formations and Penetration rates were plotted against the mud weight. From a field in Alaska, another set of data were obtained to illustrate the effect of Plastic viscosity and Methylene Blue Test (MBT) on the penetration rate. For the Water based mud, the average densities of 10.5, 11.5 and 8.9 ppg. produced average penetration rates of 25 and 24 and 37 ft/hr. respectively. Similarly, the average penetration rates of 28, 35 and 50ft/hr. were obtained by the Oil based mud densities of 11.3, 11.1 and 8.6 ppg. respectively. It can be deduced that the rate of penetration was reduced by the increase in Mud density. In order to drill effectively and efficiently, the right drilling mud density should be formulated. A substantial amount of time and drilling cost can be saved in drilling cost analysis when drilling conditions are suitable to facilitate fast penetration rates and good hydrostatic pressures.

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A successful oil well drilling depends largely on a good mud Program. During drilling, mud provid... more A successful oil well drilling depends largely on a good mud Program. During drilling, mud
provides sufficient hydrostatic pressure, removes drill cuttings and cools drill bits. Mud additives
are always required to provide sufficient hydrostatic pressure to ensure borehole stability. Barium
Sulphate (BaSO4) also known as barite is the prevalent weighting material but there is need to
develop local materials to augment the use of Barite. This study was aimed at assessing the
suitability of galena, a lead sulfide (PbS), as an alternative weighting material in drilling fluids.
Two mud samples A and B were prepared which comprised fresh water, caustic soda, bentonite
and weighting material. The weighting materials were added to the mud separately to form the
required mud weight ranges between 9.0 ppg and 15.0 ppg. Sample A was water-based mud
with commercial barite while Sample B was water-based mud with local galena. These samples
were analyzed and the density, rheological properties and solid contents were investigated.
At 9.0 ppg, the yield point of galena was 20.0 lb/100ft2 and barite 22.0 lb/100ft2 while the 10
second gel strength of galena was 5.0 lb/100ft2 and 8.0 lb/100ft2 for barite. Similarly, little
difference was observed in plastic and apparent viscosities. At 9.0 ppg, the plastic and apparent
viscosities of galena was 13.0 cp and 23.0 cp while barite was 10.0 cp and 20.0 cp. The result show that galena mud sample gave a little higher yield point and gel strength than
barite mud sample. Therefore, galena has the potential to be used as weighting material in
drilling mud in place of Barite thereby enhancing the local content initiative of the government.
When Galena is sourced locally and used it will reduce overall mud and drilling costs.

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Pressure monitoring and control using digital gauge as a tool, is one of the economical sources o... more Pressure monitoring and control using digital gauge as a tool, is one of the economical
sources of obtaining valuable information about periodic production tests. It is actually a test
to determine relative quantities of oil, gas and water produced under normal producing
conditions. They facilitate well and reserves operations and also comply with legal and
regulatory requirements. Every individual, in oil and gas well pressure and temperature
monitoring and controlling team, require the knowledge of pressure and temperature(PT)
behaviours in the annulus and tubing and at the wellhead, periodically, either during or
after an operation. One of the most reliable ways through which these parameters (PT) can
be monitored and controlled is through the use of one of the digital gauge known as “Keller
(LoggerDCX4.11) Gauge”, which is capable of recording and storing PT data. Every
operation carried out with this gauge is meant to achieve a specific goal, either to know the
pressure build-up or the pressure drawdown, during and after annulus and tubing pressure
bleed-off. When this purpose is achieved, effective well development and production is
assured.PT, well development and production are closely related in the sense that, they are
mutually dependent. For well development and production to succeed, pressure data, among
other parameters must be known. This tool is one of the most advantageous gauges for PT
well testing data. Its unique features make it easier to monitor and control oil and gas wells’ PT during development, production and maintenance.

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In formation evaluation, the knowledge of porosity, permeability and fluids saturation are very i... more In formation evaluation, the knowledge of porosity, permeability and fluids saturation are very
important in the determination of the hydrocarbon in place. These petro physical properties are
necessary to understand the nature of the reservoir and help for proper field development planning.
This was aimed at determining the petro physical properties (pore volume, bulk volume, grain
volume, permeability and fluid saturation) of a reservoir from core plugs.
A total of ten core plugs were used in this work. Archimedes immersion method was used in the
determination of the bulk volume. Liquid saturation method was used in the determination of the
porosity. The Dean-Stark extraction method was used in the determination of fluid saturation.
From the results obtained in the core analysis, the sandstone reservoir has an average porosity of
14.9±5.1%, very good permeability with an average value of 349.77±0.3 mD and a very large water
saturation value of 82±0.4%. Consequently the hydrocarbon saturation is approximately 18%.
This implies that the formation is not commercially viable to develop based on the hydrocarbon
saturation. The study shows that experimental work is one of the valid tools for making informed
decisions on the development of a field in the petroleum industry and highlights the importance of
the basic petrophysical properties in reservoir management.

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Bioavailability of Hydrophobic Organic Compounds (HOCs) to microorganisms could be a limiting fac... more Bioavailability of Hydrophobic Organic Compounds (HOCs) to microorganisms could be a limiting
factor during the biodegradation process. Application of surfactants to contaminated soil and water,
at concentrations above their Critical Micelle Concentration (CMC) values, can potentially reduce
the interfacial tension, increase the solubility and bioavailability of HOCs and thus, facilitate their
biodegradation. Studies with respect to enhanced bioremediation by surfactant addition have
greatly focused on chemically synthetic surfactants. This paper reviews the potentials of biosurfactants in remedying contaminated soils and water. Biosurfactants are surface-active
substances produced by microorganisms that can degrade or transform the components of
petroleum products. They are non-toxic, non-hazardous, biodegradable and environmentally
friendly compounds which may be cost effectively produced under ex-situ conditions; in-situ
production may be stimulated at the site of contamination and can be recovered and recycled.
Their application in bioremediation processes may be more acceptable from a social point of view
due to their naturally occurring property. Potential advantages of biosurfactants include their
unusual structural diversity that may lead to unique properties, the possibility of cost effective
production and their biodegradability. These properties make biosurfactants a promising choice for
applications in enhancing hydrocarbon bioremediation. Biosurfactants have many other
applications in various industries such as agriculture, medicine, petroleum, pharmaceutical and
cosmetics.

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This research was aimed at investigating solid particles settling in drilling fluid - Power law f... more This research was aimed at investigating solid particles settling in drilling fluid - Power
law fluid in relation to rheological properties of the fluid. Fluid of various densities and
rheologies were prepared in the laboratory. Hydroxyl methyl cellulose (HEC) was used
in this proportion 5.0, 2.5, 1.5, and 0.5 g/liter to change the rheology of the fluid with a
fluid density range from 1.003 to 1.513 g/cm3. The results show that larger particles
diameter enhance the particle settling behaviour and increases settling velocities. Also
increased fluid density reduces particle settling velocity and increases fluid viscosity.
The largest effect on the particle settling is achieved at high fluid viscosity. Therefore, it
is recommended that fluids for cutting removal should be designed with a higher
consistency index K in order to increase the fluid viscosity and thereby overcome the
settling behaviour.

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British Journal of Applied Science & Technology, 2017

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British Journal of Applied Science & Technology, 2016

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