Petroleum Engineering
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Item The prospect of using palm wine as a fluid loss control agent in water based drilling mud(Avanti Publishers, 2016) Akintola, S. A.; 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.Item Temperature and time-dependent behaviour of a water base mud treated with Maize (Zea mays) and Cassava (Manihot esculanta) starches(SCIENCEDOMAIN international, 2015) Akintola, S. A.; 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.Item Estimation of the refractive indices of some binary mixtures(Academic Journals, 2015) Isehunwa, S. O.; Olanisebe, E. B.; Ajiboye, O. O.; Akintola, S. A.Refractive index is a useful fluid characterization parameter with widespread industrial applications. The values for many pure liquids are known or readily available in literature. However, when experimental data are not available, the refractive indices of binary and multi-component liquids are often estimated from the pure components using mixing rules which are sometimes not accurate. This study was designed to measure the refractive indices and evaluate the accuracy of some commonly used mixing rules when applied to benzene-toluene, heptane-hexane, hexane-acetone, heptane-acetic acid and acetic acid-acetone binary mixtures at varying volume fractions and temperatures between 20 and 60°C. A simpler relation based on modified Kay or Arago-Biot mixing rule was demonstrated to have wider range of applicability because of the explicit temperature-dependence term.Item Evaluation of drilling muds enhanced with modified starch for HPHT well applications(Springer, 2020-10) Sulaimon, A. A.; Akintola, S. A.; Johari, M. A. B. M.; Isehunwa, S. O.The use of carboxymethyl cellulose (CMC) in oil and gas well drilling operations has improved the filtration loss and mud cake properties of drilling muds. The introduction of starch has also reduced, for example, the viscosity, fluid loss, and mud cake properties of the drilling fluids. However, normal starch has some drawbacks such as low shear stress resistance, thermal decomposition, high retrogradation, and syneresis. Hence, starch modification, achieved through acetylation and carboxymethylation, has been introduced to overcome these limitations. In this study, modified starches, from cassava and maize, were used to enhance the properties of water-based muds under high-pressure high temperature (HPHT) conditions, and their performances were compared with that of the CMC. The mud samples added with acetylated cassava or maize starch exhibited the smallest filtrate volumes and filtrate losses within the American Petroleum Institute specification. Therefore, these modified starch-added muds could replace CMC as fluid loss agents since, unlike it, they can withstand HPHT conditions.Item 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.Item 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.Item Estimation of the refractive indices of some binary mixtures(AcademicJournals, 2015-04) Isehunwa, S. O.; Olanisebe, E. B.; Ajiboye, O. O.; Akintola, S. A.Refractive index is a useful fluid characterization parameter with widespread industrial applications. The value for many pure liquids are known or readily available in literature. However, when experimental literature are not available, the refractive indices of binary and multicomponent liquid are often estimated from the pure components using mixing rules which are sometimes not accurate. This study was designed to measure the refractive indices and evaluate the accuracy of some commonly used mixing rules when applied to benzene-toluene, heptane-hexane, hexane-acetone, heptane-acetic acid and acetic acid-acetone binary mixtures at varying volume fractions and temperatures between 20 and 60˚C. A simpler relation based on modified Kay or Arago-Biot mixing rule was demonstrated to have wider range of applicability because of the explicit temperature-dependence term.Item Water cresting predictions in horizontal oil wells(Nova Science Publishers, Inc., 2012) Okwananke, A.; Isehunwa, S. O.; Adeosun, T. A.; Adeboye, Y. B.Horizontal well application has sometimes been employed as a way of minimizing excessive water production arising from coning commonly encountered during oil production in vertical wells. Lots of efforts on water coning in vertical wells have been published. Available predictive models in horizontal wells vary from rather simplistic to complex models. This study investigated the development of practical models that combine ease of use with accuracy. Conformal mapping was used to combine steady state flow, volumetric voidage and pressure drop due to gravity effects in horizontal wells to obtain models that predict critical rates and breakthrough times. The results were compared with some existing correlations under varied reservoir fluid and rock properties. The models were also applied to vertical wells. It was observed that critical rates and breakthrough times in horizontal wells are affected directly by effective permeability, well length, oil column height, density contrast between water and oil, the height of the water crest. There is however, an inverse relationship with oil viscosity and production rate. The correlations also provide a means of comparing the performance of horizontal and vertical wells.Item New referencing technique for reservoir oil viscosity estimation(EuroJournals Publishing, Inc., 2012) Isehunwa, S. O.Reservoir oil viscosity is important in understanding reservoir flow behaviour, facilities design and sizing and in the computation of recovery performance, well' productivity and lift requirements. Direct viscosity measurements are expensive or sometimes unavailable hence empirical correlations are often used for predictions. However, several published correlations are either too simplistic or complex for routine operational use and improved methods continue to receive attention. This study used a semi-theoretical approach to relate reservoir oil viscosity to well-head oil viscosity which can easily be obtained. Results were analyzed statistically and tested with field data obtained from the Niger Delta. The viscosity relation factors developed gave an absolute average relative error (AARE) of 14.1% for undersaturated reservoirs and an AARE of 2.4% for saturated oil reservoirs. It is concluded that measured well-head oil viscosity can be used with good accuracy, as reference liquid instead of dead oil viscosity that has been commonly used for estimating reservoir viscosity.Item A model for predicting sand production in horizontal wells(Nova Science Publishers, Inc., 2012) Isehunwa, S. O.; Nwokeke, N.; Olanrewaju, O.Sand produced along with oil and gas causes operational, safety, environmental and severe economic challenges. The cost of installing sand control facilities which may not really be needed could also be substantial. Therefore, determining the critical flow rate for the onset of sand production is very important. There are several published studies on sanding in vertical wells, but few on horizontal wells, which have now become very prominent in the industry. The aim of this study was to develop a simple but robust model for predicting sand rates in horizontal wells. A novel geomechanical model incorporating gravity, buoyancy, drag and lift forces was developed and validated with data from 3 oil fields in the Niger Delta. The results showed that sand production could take place in horizontal wells even at low production rates but increases at high production rates in the fields of study. Critical sand rate is also affected by horizontal well length, fluid viscosity and diameter of the sand particles.