scholarly works

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

Browse

Author: search.filters.author.Isehunwa, S. O.

Search Results

Now showing 1 - 10 of 23
  • Thumbnail Image
    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.
  • Thumbnail Image
    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.
  • Thumbnail Image
    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.
  • Thumbnail Image
    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.
  • Thumbnail Image
    Item
    Analysis of water cresting in horizontal wells
    (Society of Petroleum Engineers, 2009) Okwananke, A.; Isehunwa, S. O.
    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 also observed that critical rates and breakthrough times in horizontal wells are affected directly by effective permeability, well length, oil column height, density contrast between wafer and oil, !he height of the water crest. There is however, an inverse relationship with oil viscosity and production rate. It is concluded that simple and accurate correlation that can be applied to coning problems in both horizontal and vertical wells have been developed. They provide a means of comparing the performance of horizontal and vertical wells.
  • Thumbnail Image
    Item
    Prediction of the viscosity of a water - base mud treated with cassava starch and potash at varying temperatures using factorial design
    (2007) Okumo, I.; Isehunwa, S. O.
    In order to monitor and control the properties of drilling fluids, measurements are routinely made at the surface. However, these surface measurements may not be representative of down-hole properties where the desired functions of hole cleaning and other related issues are critical to the success of the drilling operations. Consequently, it is important to make necessary adjustments of the fluid properties obtained at ambient conditions to give estimate of properties at high temperatures and pressures. The principle and method of factorial design have been used to develop a model, which makes possible the prediction of drilling fluid viscosity at varying temperatures. Cassava starch and potassium carbonate were used as local additives in a water based bentonic drilling fluid after running a quality check 23 full factorial design experiments which consider temperature, starch and potash as factor variables and viscosity as the response variable were conducted. The main effects as well as the interaction effects were determined and examined. The results were analyzed and a predictive model was obtained. Viscosity values obtained using the model were compared with the experimental results and it was observed that the model has an accuracy of93.6%. This method makes possible the prediction of the viscosity of drilling fluids at varying temperatures, hence the treatment of mud systems can be determined ahead of time.
  • Thumbnail Image
    Item
    Estimation of developed reserves in gas lifted wells.
    (Society of Petroleum Engineers, 2009) Daniel, A.; Isehunwa, S. O.
    Reliable estimates of petroleum reserves are invaluable in reservoir management decisions and economic evaluation. Classical decline curve analysis techniques have been routinely used and are generally accepted in the industry to reliably estimate developed reserves up to a predetermined economic limit qec in oil wells. However Decline curve analysis techniques are based on the assumption that past production trends and their controlling factors will continue in the future and therefore can be extrapolated for predictions. During gas lifting, production trends could be distorted hence there is need to modify the classical decline curve analysis equation. In this study, the principle of superposition has been applied to the entire duration of production (t) of wells producing under gas lift. This resulted in the so called Double Semi log equation for well decline analysis. Model validation with two fields in the Niger Delta area show excellent results and the economic advantage of gas lifting. The Models showed excellent correlation coefficients with available field data. It is concluded that gas lift could increase the reserves in some wells. Furthermore the Double Semi log technique provides a better and more reliable theoretical foundation, easier and more reliable technique for decline analysis in gas lifted wells.
  • Thumbnail Image
    Item
    A two-parameter correlation for predicting oil recovery factor in water-drive reservoirs
    (Society of Petroleum Engineers, 1994) Isehunwa, S. O.; |Nwankwo, S. U.
    A simple correlation has been developed for estimating primary recovery factors for Niger Delta oil reservoirs. The correlation which was developed, from data collected across the Niger Delta, is valid for reservoirs with strong water drives. Only two major parameters are required for the recovery factor calculations in this work, unlike other multi-parameter correlations. This makes this correlation very easy to apply. An expression has also been included for predicting residual oil saturation, where core or log analysis data are not available. The results obtained using these models have been compared with other published models, and applied to many case studies, with better predictions. Graphical and statistical error analyses also confirm good correlations. These correlations should also, yield good predictions for reservoirs from other regions that have similar reservoir and fluid characteristics.
  • Thumbnail Image
    Item
    Carbon(IV)oxide Capture and Sequestration in Nigeria: Prospects and Challenges
    (Society of Petroleum Engineers, 2006) Isehunwa, S. O.; Makinde, A. A.; Olamigoke, O.
    The capture and storage of carbon dioxide (CCS) produced during the combustion of fossil fuels now offers one option for attaining large scale reductions in the emissions of greenhouse gases and thus, promote a clean environment. It is now becoming clear that CCS technologies could promote the use or consumption of fossil fuels than otherwise previously thought. This paper presents an overview of the techniques involved in the capture and sequestration of carbondioxide(CO). The opportunities and the challenges of the application of CCS in Nigeria are considered. It is concluded that the development of gas utilization schemes and power plants makes it imperative for Nigeria togive attention to CCS technologies.
  • Thumbnail Image
    Item
    Application of generalized pressure perturbation principle to cubic equation of state formulation
    (Society of Petroleum Engineers, 2005) Isehunwa, S. O.; Falade, G. K.
    Cubic equations of state are commonly used for predicting the properties of reservoir fluids. They are simple to use and require few parameters during computations. They have also been found to produce results that are comparable to the more rigorous multi-parameter equations. However, they are still regarded by many as mere comprehensive correlations of fluid properties because of a number of weaknesses and /imitations. This work addresses two weaknesses of cubic equations of state commonly highlighted in literature, viz: that they do not seem to have deep theoretical foundations and are not as accurate as non-cubic equations. A pressure perturbation technique based on a simple adaptation of the Weirtheim's first order thermodynamic perturbation theory has been developed and used to formulate a cubic equation of state. The practical equation formulated was applied to pure fluids and samples of Niger Delta Petroleum fluids. The results show more accurate predictions than the commonly used SRK and PR equations. This work suggests that cubic equations could have deeper theoretical.