Papers by Author: Ebenezer Adom

Abstract: Most of the heavy oil resources in the world are in sandstone reservoir rocks, the majority of which are unconsolidated sands which presents unique challenges for effective sand management. Because they are viscous and have less mobility, then appropriate recovery mechanisms that lower the viscosity to the point where it can readily flow into the wellbore and to the surface are required. There are many cold and thermal recovery methods assisted by gravity drainage being employed by the oil industry. These are customised for specific reservoir characteristics with associated sand production and management problems. Steam Assisted Gravity Drainage (SAGD) based on horizontal wells and gravity drainage, is becoming very popular in the heavy oil industry as a thermal viscosity reduction technique. SAGD has the potential to generate a heavy oil recovery factor of up to 65% but there are challenges to ‘’realising the limit’’. The process requires elaborate planning and is influenced by a combination of factors. This paper presents unique models being developed to address the issue of multiphase steam-condensed water-heavy oil modelling. It addresses the effects of transient issues such as the changing pore size distribution due to compaction on the bulk and shear viscosities of the non-Newtonian heavy oil and the impact on the reservoir productivity, thermal capacity of the heavy oil, toe-to-heel steam injection rate and quality for horizontal well applications. Specific case studies are presented to illustrate how the models can be used for detailed risk assessment for SAGD design and real-time process optimisation necessary to maximise production at minimum drawdown. Nomenclature

Abstract: Criticality of rheology for heavy oil recovery is the main purpose of this paper supported by different results. The Bingham Plastic, Power Law and Herschel Bulkley rheological models have been adopted for the purpose of this paper. Rheological characterisation was carried out for different temperatures. Rheological behaviour of non-Newtonian heavy oil for different shear rates is analysed in this paper. Effective shear and bulk viscosities for different flow rates are compared for all rheological models. Using the horizontal well productivity model, the drawdown values for all rheological models are determined. Similarly for the sand management purpose the critical rates of Newtonian and these three non-Newtonian fluids are plotted to determine the critical drawdown values for each type of fluid. Impact of drainage profile on the effective viscosities is also compared for different drainage profiles. Shear rate models are proposed in this paper for Bingham Plastic, Power Law and Herschel Bulkley rheological models. The new Micro-PVT equipment is also introduced for determining the PVT properties and rheological behaviour of heavy oil. Nomenclature

Abstract: The recent interest in boiling heat transfer in small diameter tubes has led to the study of boiling heat transfer outside a compact tube bundle of diameter 3mm. The bank comprised 3 columns each of 10 stainless steel electrically heated tubes of 3mm outside diameter, with pitch to diameter ratio of 1.5 in an in-line arrangement. These tests were carried out using distilled water and R113 at nominal atmospheric pressure over a range of heat fluxes between 4-21 kW/m2 for mass fluxes from G=5.6 - 32.8 kg/m2s. The recent three-zone evaporation model developed by Thome, Dupont and Jacobi for boiling inside micro channels was used to compare with experimental results as photographic study showed that bubbles confined within the bundle were responsible for the heat transfer enhancement observed. It was observed that the three state model was promising in its application to the bundle arrangement as the confinement number Co for bundle has been shown to be in the order of 0.63

Abstract: An experimental study has been carried out using a tube bank representing a section of a tube bundle. The bank comprised 3 columns each of 10 stainless steel electrically heated tubes of 3mm outside diameter with pitch to diameter ratio of 1.5 in an in-line arrangement. Flow rate through the test section was controlled. Each tube in the central column was instrumented to permit determination of the tube temperature and heat flux, hence permitting calculation of the heat transfer coefficient. These tests were carried out using distilled water at nominal atmospheric pressure over a range of heat fluxes between 6 - 21 kW/m2. Results of the heat transfer tests are presented and compared with correlations used for conventionally sized bundles. Correlations developed for large tube bundle overestimate the experimental results.