scholarly works

Permanent URI for this collectionhttps://repository.ui.edu.ng/handle/123456789/564

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Now showing 1 - 9 of 9

Deconvolution and interpretation of well test data ‘masked’ by wellbore storage in a build up test
(2015) Akintola, A. S.; Oriji, A. B.; Duru, K. M.
When a well test contains a series of different flow rates, or a continuously varying flow rate, the combination of the pressure transients due to varying flow rate is called convolution. while deconvolution means removing a distorting effect upon the variable of interest. This paper is on the study of an analytical technique that can be used to explicitly deconvolve wellbore storage distorted well test data using pressure data and the flow rate. Then to determine the reservoir properties from this deconvolved well test data by using the conventional well test interpretation methods. Also, the comparison of the material balance deconvolution method results with the β-deconvolution method result were carried out and then used to determine which method was a better deconvolution tool. The results showed that the material balance deconvolution technique performed very well with minor discrepancies and gave better estimation of the reservoir parameters.
Determination of some petrophysical properties of reservoir rocks in the Niger Delta
(2015) Akintola, A. S.; Akpabio, U. J.; Nduamaka, C. F.
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.
Development of thermodynamic model with gopal’s constants for the Inhibition of gas hydrates formation in gas pipeline
(2019) Akinsete, O. O.; Akintola, A. S.; Folayan, O. G.
Hydrate deposition remains a very willful one in the oil and gas industry and costs the industry billions of dollars worldwide for prevention and remediation in pipelines and flowlines. An economic and environmentally friendly solution to the prevention of hydrate formation is prohibitively expensive. In this study, a thermodynamic model for hydrate inhibition in gas pipelines by applying the Joule Thomson Expansion phenomenon was developed. The model is a function of the specific gravity, initial and final temperatures, and the initial and final pressures. This developed model comes with the Gopal's constants that make the model trainable to fit data from various expansion processes. The results obtained for sweet gases were compared with that presented by the Gas Processors Suppliers Association (GPSA) and an error of less than 5% (R2 = 0.9629) was observed. The effect on sour gases was also considered. The pseudo-reduced temperature ranges from 1.05
Electrical resistivity measurements of downscaled homogenous rocks for network model validation
(2011-06) Olafuyi, O. A.; Ikhouria, A. A.; Akintola, A. S.
Knowledge of electrical resistivity for reservoir rocks is crucial for a number of reservoir engineering tasks such as the determination of oil-in-place and the calibration of resistivity logs. Those properties can now be predicted by numerical calculations directly on micro-CT images taken from rock fragments typically having a bulk volume of 100mm3. The experimental data used to validate those predictions are obtained on conventional cores having bulk volumes of the order of 10, 000mm3. A better validation of micro-CT technique would be to use the same core size for both imaging and flow experiment. Experimental data for electrical resistivity measurements using micropore membrane and centrifuge desaturation techniques are presented for cores having bulk volumes from 10, 000mm3 down to 100mm3. Both 2 - and 4 - electrode techniques were applied to measure the resistivity index. Simple fluids like brine and air were used for clear wettability. Homogeneous sandstone cores (Berea and Bentheim) and a carbonate core (Mount Gambier) were used in the experiments. The results demonstrate that reliable experimental data of resistivity index can be obtained for the small cores of homogeneous porous rocks at sensitized frequency. Such data are of immense interest for validating the predictive value of network models based on micro-CT imaging of rock fragments with bulk volumes as small as 100 mm3.
Evaluating the effect of drying methods on the properties of a water base drilling mud
(Science Publishing Group, 2021) Akintola, A. S.; Arigbe, T. E.
It is important to understand the properties influencing the efficiency of a drilling fluid while drilling for oil and gas. As a result, drilling fluid must be designed in order to comply with three important requirements which are easy to use, cost effective and being environmentally friendly. Several studies have been carried out on the use of local materials as suitable substitute for imported additives. This study focuses on the use of starch processed from local cassava (Manihot esculenta Crant), (TME 419) using the process of wet milling and dried using three different methods namely: oven drying, direct heating and sun drying Due to this short coming resulting from the use of native starch, the starch was chemically modified using the process of esterification before being used as additive for treatment of the water-based drilling. The mud samples were prepared using Wyoming bentonite and distil water as the base fluid. Varying concentration of additives (0.5, 1.0 and 1.5 g) were added to the different mud samples and the laboratory test carried out in accordance with the API Recommended Practice 13B at varying temperatures (30, 50.70 and 90°C). The various mud samples rheological properties was determined using a Fann35A rheometer and the filtration properties using a low –Temperature and High –Pressure API Filter Press at 100 psi with a 3.5” filter paper. The mud samples labelled labeled A, B and C were treated with oven dry, direct heat and sundry modified starches, respectively. While two control mud samples were prepared using low viscous Carboxymethyl cellulose for mud sample D and extra high viscous CMC in sample E. Although the Viscosity and fluid loss profiles result of the mud samples comparable performance with that of the commercial CMC’s. However, mud samples treated with oven dried starches presented the best results in their rheological as well as fluid loss properties.
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.
Pressure gradient prediction of multiphase flow in pipes
(2014) Akintola, A. S.; Akpabio, U. J.; Onuegbu, M.
Pressure traverse in multiphase flow differs from single phase flow due to the differential flow rates of the different phases. Correlations developed to predict multiphase flow pressure traverse are mostly for vertical wells but Beggs and Brill model is one of the few models that is used for inclined pipes. The work seeks to show the improvement in the modification of the model. This project is based on studies carried out on multiphase fluid flow in pipes of any inclination using the Beggs and Brill flow model as the focus. Two cases were considered, the liquid holdup correction and Gas Liquid Ratio (GLR) variations in which the Beggs and Brill and Beggs and Brill Traverse models were compared. Due to the empirical nature of the Beggs and Brill model, pressure gradient predictions are far from accurate when compared with measured data in the field. This project seeks to reduce the error margin between predicted pressure gradient values and measured data. It was observed that for the same reservoir, fluid, and pipe properties, the Beggs and Brill Traverse Model is a better prediction tool than the Beggs and Brill model. Prediction errors were seen to increase with increase in length for GLR above 400 scf/stb while they were more accurate for pipes between 12,000 and 17,000 ft and pressures between 3,000 and 4,500 psi. However, the Beggs and Brill Traverse Model, is limited by the choice of correlations used in the computation of fluid properties.
The prospect of using palm wine as a fluid loss control agent in water based drilling mud
(Avanti Publishers, 2016) Akintola, A. S.; Isehunwa, S. O.; Oboh, S. M.
The need to advance and project the use of local materials as suitable drilling fluid additive in the oil and gas industry in Nigeria led to the research on the possible use of palm wine and potash as additives in a water base drilling mud. A comparative study of these local materials (palm wine and potash) with imported foreign materials (lignite and caustic soda) as control were used in investigating the properties of a water base drilling fluid. A laboratory investigation of the effects of temperature and aging time on the properties of water-base drilling fluid is made with Fann Model 800 High Temperature and a High Pressure (HTHP) Viscometer, according to the API recommended standard practice. The results obtained showed similarity in the drilling fluid’s rheological and filtration properties; mud weight and pH values for both local and foreign additives. The result from the mud sample prepared from the palm wine and potash had apparent viscosity, plastic viscosity and yield point decreasing steadily with increase in temperature for all aging time just as shown with the control sample, while the aging effect diminishing as the aging time increases. The potash was seen to have increased the mud pH from 7.0 to 12.9 pH units. The results, shows that both palm wine and potash can be used as suitable in water base drilling mud additive.
Temperature and time-dependent behaviour of a water base mud treated with maize (zea mays) and cassava (manihot esculanta) starches
(2015) Akintola, A. S.; Isehunwa, S. O.
Starch, one of the commonly used additives in drilling fluids, degenerates with time under cyclic temperature and pressure loads, causing changes in mud properties. This study was designed to establish the effect of temperature and aging on water base mud treated with starches prepared from maize (Zea mays) and cassava (Manihot esculanta) starches. The effect of potash and tannathin on the muds was also investigated. Plastic viscosity of treated samples at varying temperatures (24.4, 40.0, 60.0 and 80.0 O C) was determined using standard API practices over a period of 72 hours. At ambient conditions, the plastic viscosity of samples treated with maize and cassava varied between 5 and 7 cp and increased to between 6 and 12 cp when the samples were further treated with potash. Plastic viscosity for industrial starch varied from between 5 and 6 cp but increased to between 7 and 10 cp when further treated with potash. Predictive models for plastic viscosity and yield point gave coefficient of variance between 90 and 92% respectively. However, all the starches degenerated within 24 hours and would require further treatment to prevent biodegradation.