Petroleum Engineering
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Item TECHNICAL AND ECONOMIC EVALUATION OF NANOFLUID ALTERNATING-BRINE FLOODING FOR ENHANCED OIL RECOVERY IN NIGER DELTA RESERVOIRS(2022-02) OMOTOSHO, Y.ANanofluid flooding in the petroleum industry has generated growing interest because of its potential to greatly improve oil recovery. However, studies have reported that injection of nanofluid could lead to impaired permeability due to adsorption of nanoparticles on reservoir rocks thereby incurring high costs. The use of single Nanofluid Flooding (NF) has not appreciably reduced permeability impairment. This study was therefore, designed to investigate the technical and economic viability of Nanofluid-Alternating-Brine Flooding (NABF) for enhanced oil recovery in Niger Delta reservoirs. Eight sandstone core samples obtained from Niger Delta, were characterised for porosity and permeability using Helium-Porosimeter and Permeameter, respectively. Densities and viscosities of crude oil samples and brine (Salinity: 32.2g/L) were determined using pycnometer and viscometer, respectively. Core samples were initially saturated with brine and drained with crude oil, to determine the initial Water Saturation (SWi). Silica nanoparticles of size: 20-70 nm, were dispersed in brine at concentrations ranging from 0.01 to 3.00 wt%. Interfacial Tensions (IFT) between oil and nanofluids were measured. Brine Flooding (BF) of core samples was conducted at 2.00 cm3 /min. The Optimum Concentration (OC) and Optimum Injection Rate (OIR) during NF were determined by injecting each nanofluid concentration at 0.50, 1.00, 2.00 and 3.00 cm3 /min. The NABF was carried out at OC and OIR. The Oil Recovery Factors (ORF) for all experiments were computed using material balance. The images of pre-flooded and post-flooded core samples were obtained using Scanning Electron Microscope. Nanoskin factors (Sn) were determined for NF and NABF and compared with the analytical model developed from Darcy’s equation. The ORFobtained were upscaled for field application and evaluated for Threshold Oil Price (TOP). Risk analysis with varying ORF, Capital Expenditure (CAPEX) and Operating Expenses (OPEX) was carried out using a commercial software. Data were analysed using ANOVA at 𝛼0.05. Porosity and liquid permeability for the samples were 17.0-30.0% and 1.1x10-8 -1.6x10-8 cm2 (1104.9-1584.0 md), respectively. The densities of crude oil and brine were 0.88 and 1.02 g/cm3 , while their viscosities were 3.0x10-4 kgms-2 (3.0 cp) and 1.0x10-4 kgms-2 (1.0 viii cp), respectively. The SWi were 11.0-18.4%. The IFT were 1.9x10-2 -2.3x10-2 N/m (18.5- 23.0 dynes/cm) while the OC and OIR for NF were 2.00 wt % and 2.00 cm3 /min, respectively. The ORF for BF, NF and NABF were 68.9-73.1, 63.8-66.2 and 83.8-86.2%, respectively. The pre-flooded cores had evenly distributed grain matrices void of external particles while permeability impairment was observed for NF. Permeability impairment reversal was observed during NABF. The predictive model for Sn agreed with the experimental result. Economic analysis revealed that for unit CAPEX (N13,985.56/bbl; $34.00/bbl) and OPEX (N1,867.48/bbl; $4.54/bbl), at discount rate of 10.0%, TOP was N20,196.79/bbl ($49.10/bbl). Risk analysis on profitability showed that TOP for proved, probable and possible ORF were 33,400.81, 19,197.24 and N12,545.87/bbl (81.20, 46.67 and $30.50/bbl), respectively. The order of impact of the economic variables on profitability was ORF>CAPEX>OPEX. Improved oil recovery in Niger Delta reservoirs was achieved using nano-alternating-brine flooding with minimal permeability impairment. The method is also profitable within the stipulated oil price regime.Item DEVELOPMENT OF A REAL-TIME PETROLEUM PRODUCTS ADULTERATION DETECTOR FOR LIQUID AND PARTICULATE CONTAMINANTS(2022-12) OLOTU, O.OAdulteration of petroleum products with the resultant safety, health, environmental and economic impact on the end-users is a challenge in Nigeria and many developing countries. The current commonly used techniques by regulatory agencies and some end-users for quality assurance of the petroleum products are time-consuming and expensive. The development and use of real-time adulterated petroleum products detector in Nigeria will therefore alleviate these problems. This study was therefore designed to develop a device for real-time detection of petroleum products adulterated with liquid and particulate contaminants. Pure samples of Premium Motor Spirit (PMS), Automotive Gas oil (AGO) and Dual Purpose Kerosene (DPK) were collected from some major petroleum products marketers. Samples of distilled water, naphtha, commercial ethanol, pure and used commercial lubricating oil, and High Pour Fuel Oil (HPFO) were also obtained and used as liquid contaminants; while sawdust, ash and fine-grain sand were used as solid particulates. At temperatures 23:1:28oC, binary mixtures of the products mixed with liquid contaminants were prepared (100:0, 95:5, 85:15, 75:25, 70:30, 65:35 … 15:85, 5:95,0:100 v/v). Likewise, a fixed volume of pure petroleum products was mixed with varying quantity of solid particulates (0, 2, 4, 6, 8, 10 g). The specific Gravity (SG) and Interfacial Tension (IFT) of the pure samples, binary mixtures were determined according to ASTM D1298 and D971 standards, respectively. These physiochemical properties (SG and IFT) of pure and contaminated fuel samples were used to develop a mathematical model. The model was then simulated into a microcontroller-based detector. A microcontroller of PIC16f876 microchip with multiple input/output pins and a load cell sensor with real-time response was used. The microcontroller takes the reading of the weight of liquid from the sensor to get the SG and IFT of the liquid in real-time. Values of SG and IFT of pure and contaminated samples of petroleum products were obtained using the developed adulteration detector and compared with laboratory measurements and those obtained using Kay’s mixing rule. Data were analysed using ANOVA at α 0.05. The SG and IFT (dynes/cm) of the pure samples were (PMS) 0.833, 47.0; (AGO) 0.812, 28.0; (DPK) 0.803, 25.0, for liquid contaminants ranged from (PMS) 0.853-0.890, 44.6-25.0; (AGO) 0.807-0.804, 46.2-29.5; (DPK) 0.811-0.947, 46.4-38.0 and for solid contaminants ranged from (PMS) 0.887-0.910, 47.8-27.2; (AGO) 0.884-0.887, 29.2-30.0; (DPK) 0.817-0.857, 25.8-32.8, respectively. The SG and IFT from Kay’s mixing rule ranged from (PMS) 0.851-0.900, 48.4-25.6; (AGO) 0.850-0.871, 40.1-35.4; (DPK) 0.864-0.881, 42.4-36.4, respectively. Adulteration of products was detected at 20.0-30.0% by volume and 10.0-20.0% by mass of contamination, respectively. The designed adulteration detector responded to the sample in real-time of 3-5s, displayed GREEN and RED for pure and adulterated samples, respectively, with their numerical SG values within ±0.01% of actual measurements. There was no significant difference between the actual and detected SG and IFT of the adulterated samples. A device that detects petroleum products adulteration in real-time and ambient temperature was developed. The method can be adapted to real-time evaluation of similar binary mixtures.Item Improving the rheological and filtration properties of an invert emulsion mud using a locally sourced modified polymer(2022) Akintola, S.A.; Sanusi, H.; Oyelola, C.Drilling fluid is designed for easy to use, cost effective and environmentally friendly. Several studies have been carried out on the use of local materials such as starch as suitable substitute for imported additives. Due to this short coming resulting from the use of native starch, the potatoes starch was chemically modified using the process of graft copolymerization, before being investigated as an additive for treatment of invert emulsion drilling. Three mud samples labelled (Base fluid, Copolymer 1 and Copolymer 2) were prepared and diesel labelled Base fluid served as control. Varying concentration of additives (1.0 and 2.0 g) were used at added to the different mud samples and laboratory study was carried out using the API Recommended Practice at varying temperature. This study is aimed at improving the properties of an invert emulsion mud using chemically modified locally sourced pomoea batatas as additiveItem Corrosion protection by novel conversion coatings on structural AI 6061(2022) Oki, M.; Adediran, A. A.; Ikechukwu, A.; Onokohwomo, C. O.; Bosa, C.; Akintola, S. A.; Adesina, O. S.Chromate conversion coatings have witnessed limited acceptability in recent times. The coatings contain Cr (VI) species that have been classified as environmental hazards and injurious to human. Thus, the use of environment-friendly and non-carcinigenic novel inorganic- inorganic hybrid conversion coatings are being explored. Vanadate (VCC), hybrid Vanadate/Molydate (HCC) conversion coatings on A16061 have been classified in terms of corrosion and adhesion performance with reference to the untreated alloy. Natural exposure tests in the atmosphere and stanant near-neutral 3.5% sodium chloride solution, as well as patentio-dynamic polarization measurements showed that the corrosion rate for HCC is lower for Vanadate, which in turn outclassed the ‘bare’ alloy. However, clusters of passive incipient pits were revealed on the former after 120 h of exposure in stagnant chloride solution. Both conversion coatings outperformed the untreated aluminiun alloy after atmospheric corrosion and adhesion tests.Item Investigation of the effect of some salts on the rheological properties of xanthan gum and gum arabic present in a drilling fluid(2022) Okaome, P.; Akintola, S.The rheological properties of a drilling fluid are important because they allow for extensive examination of the viscosity, fluid flow profile, pressure loss, equivalent circulation density, and hole cleaning capability making it the foundation for all wellbore hydraulics. The viscosity, gel strength, and yield point of Gum Arabic and Xanthan Gum contained in a fresh water-based drilling fluid were investigated in the presence of three distinct salts: calcium chloride (CaCl2), potassium chloride (KCl), and sodium chloride (NaCl). The salts were introduced separately to three distinct fresh water-based drilling fluid samples in increasing weights. The Fann V-G viscometer was used for the required rheology properties measuring the RPM and gel strength. The plastic viscosity, apparent viscosity, and yield point were calculated from the experimental data. With increasing the salt concentration, the plastic viscosity, apparent viscosity, yield point, and gel strength all decreased, which was observed for all three salts used. This research aimed to investigate the effect of three different salts; Calcium chloride (CaCl2), Potassium Chloride (KCl), and Sodium Chloride (NaCl) on the rheological properties of Gum Arabic and Xanthan Gum viscosified water-based drilling fluid.Item Modeling the effect of modified local polymer on the rheological and filtration properties of water-based drilling fluid(2021-10) Akintola, A. S.; Adeniji, A. A.; Mogbolu, U. J.In order to achieve a successful drilling operation, the drilling fluid used must be properly designed. Water based drilling muds that are formulated to suit drilling requirements include additives like clays for higher viscosity and starch for better filtration control properties. Locally available yams (Dioscorea) are a good source of starch, with good absorbent properties that give its good filtration control properties but poor gelling properties due to the easily soluble branched chained Amylopectin molecules which causes it to easily degrade. While mud samples treated with Carboxylmethyl cellulose (CMC) was used as control. Chemical modification of starch has been researched to be a good method of improving its gelling properties in water based mud which in turn improves the rheological properties of the mud. Cross linking agents like sodium acetate and ammonium phosphate are used to cross-link the Amylopectin and Amylose molecules in the starch thus making them less degradable. An experimental study was carried out to reduce the yams starch bio-degradable nature via chemical modification with some cross-linking agents (sodium acetate and ammonium phosphate). The results from the rheological and filtration control test carried out on the formulated mud samples treated with modified yams starch additive gave higher gel strength and yield point, exceptional shear thinning ability, lower plastic viscosity and a good but lower fluid loss control when compared to with the control samples. A Factorial design was developed to predict the rheological properties of the mud system at different temperatures and varying starch quantities. The results of the mud samples treated with the non-modified starches, modified yam starches and imported viscosifier (CMC) are indicators that the modified starches improved its gelling nature thereby giving the drilling mud a better rheological properties.Item Fuel energy potential of pyrolyzed municipal solid wastes(2021) Okareh, O. T.; Adegoke, S. O.; Richard, R.; Akintola, S. A.; Adeleke, A. A.; Ikubanni, P. P.Municipal wastes have become a menace and the recycling of these wastes has been the focus of many researches. In this study, municipal plastic wastes were converted to energy fuel using pyrolysis using a locally fabricated vacuum pyrolyzer. 6 kg of municipal plastic wastes (PP, PET and PS) were collected, grounded into chips using a knife milling machine and were fed into the pyrolyzer to undergo thermal degradation at a temperature of 500oC with holding time of 4-5 hours. The pyrolyzed oil was collected into a Pyrex condenser unit and subjected to pseudo-distillation at 100oC to obtain the volatile com-ponents. The percentage pyrolyzed oil mass yield was calculated using mass balance equation. The liquid fuel was analyzed for its physical properties using ASTM methods, while the chemical properties were characterized using FTIR and GC-MS. The pyrolytic process showed the percentage mass yield of the pyrolyzed oil for the municipal plastic wastes oil, char, and non-condensable gas as 82.0, 16.0 and 2.0%, respectively. The derived energy fuel indicated a cloud point, pour point, density and flash point of -26.0oC, -28.0oC, 0.839 g/cc, and 50.0oC and -28.0oC, -35.0oC, 0.744 g/cc, and 30.0 C for pyrolyzed oil and distillates oil, respectively. The FTIR and GC-MS results of the liquid pyrolyzed oil indicate the presence of aliphatic, alkane, alkene, and aromatic hydrocarbons of carbon number C9-C44 in the energy fuel. Physicochemical characterization of the recovered oil indicated similarities with the conventional fossil fuels. The technology has proven to be effective in solving the environmental problems.Item Optimization of drilling cost using artificial intelligence(Medwin Publishers, 2021-11) Akintola, S. A.; Olawoyin, A. B.Drilling operation in the oil and gas industry takes most of the well cost and how fast the drilling bit penetrate and bore formation is termed the rate of penetration (ROP). Since most of the cost incurred during drilling is related to the drilling operations, three is need not only to drill carefully, but also to optimize the drilling process. A lot of parameters are related to the rate of penetration which are actually interdependent on each other. This makes it difficult to predict the influence of every single parameter. Drilling optimization techniques have been used recently to reduce drilling operation cost. There are different approaches to optimizing the cost of drilling oil and gas wells, some of which include static and /or real time optimization of drilling parameters. A potential area for optimization of drilling cost is through bit run in the well but this is particularly difficult due to its significance in both drilling time and bit cost. In this sense, as a particular bit gets used, it gets dull as its footage increases, resulting from the reduction in the bit penetration rate. The reduction in penetration rate increases total drill time. In order to optimize bit cost, it is desirable to find a trade-off between the two by a bit change policy. This study is aimed at minimizing drilling time by use of artificial intelligent for the bit program. Data obtained from a well in the Niger delta region of Nigeria was used in this study and the cost of optimization modelled as a Marcov decision process where the intelligent agent was to learn the optimal timings for bit change by reinforcement policy Iteration learning. This study was able to achieve its objectives as the reinforcement learning optimization process performed very well with time as the computer agent was able to figure out how to improve drilling cost over time. Better results could be obtained with a better hardware and increased training time.Item Application of agro–waste materials for improved performance of water–based drilling fluid(2021-07) Akintola, S. A.; Orisamika, B. O.; Odetola, K. O.Bio–resources and its derivatives have distinctive potential in various industrial applications and solutions especially for captivating usage in drilling fluid formulations for the petroleum industry. Drilling fluids formulations have tremendously advanced through increasing research and development of unique additives to improve their functionalities and meet specific properties in well design operations. In this article, water–based mud formulated with powdered and ash products derived from plantain and banana peels were evaluated. The effects of varying concentrations of these additives and the blends on the performance of the mud were examined by comparison with Low Viscosity Sodium Carboxymethyl Cellulose (LV CMC) for rheology and sodium hydroxide (NaOH) for pH control. The rheology of the mud improves with increasing concentration of the powdered products in a way similar to that of LV CMC. However, powdered banana peels most effectively improved the rheology of the mud to attain 10cp plastic viscosity (PV), 13lb/100sq.ft yield point (YP), 16lb/100sq.ft and 23lb/100sq.ft gel strength at 10seconds and 10minutes, respectively. Plantain peel ashes compared favourably with NaOH in controlling the pH of the mud. Further modification of the products to achieve the same properties as LV CMC is recommended in subsequent studies.Item Modelling the effects of modified local starches on the rheological and filtration properties of a water – based drilling fluid(2021-07) Akintola, S. A.; Isehunwa, S.This study is designed for the comparative analysis of chemically modified local starches used as additive in improving the rheological and fluid loss properties of a water- based drilling fluid. Additives are added to a drilling fluid in order to enhance the various functions of the drilling mud. Different drilling fluid samples were formulated without additive and with various concentrations modified starches. A laboratory investigation on the drilling fluid rheological and filtration properties using the API recommended standard procedures, pressure were studied at 1000 psi with a temperature range of 40.0 to 180.0 ° C, using a High Pressure High Temperature, (HTHP) rheometer and Fann Model 35A respectively From the analyses of the experimental results, it was observed that effective viscosity, plastic viscosity and yield point decrease steadily with increase in temperature. The experimental results, water based drilling fluid treated with chemically modified local starches improves the filtration and rheological properties of the drilling mud. Finally, this paper also presents a predictive model equation good enough to analyse trends and predict future values for effective and plastic viscositie