TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractCanada has declining reserves of conventional oil, but vast reserves of heavy oil and bitumen. Over 90% of the world's heavy oil and bitumen trapped in sandstones and carbonates are deposited in Canada and Venezuela. Up to 80% of estimated reserves could be recovered by in-situ thermal operation. The current in-situ thermal technologies such as cyclic steam stimulation (CSS), steam flooding and steamassisted gravity drainage (SAGD) are energy intensive and use large quantities of fresh water. Increasing pressure of environmental concerns and the threat of a carbon tax will make it imperative to find new oil extraction technologies that are less energy intensive and that use less water. Combining technologies in the form of hybrid steam-solvent processes offer the potential of higher oil rates and recoveries, but at less energy and water consumption than processes such as SAGD.At the Alberta Research Council, new hybrid steam-solvent processes have been undergoing development in recent years. The Expanding Solvent-SAGD (ES-SAGD) (1-2) , is aimed at improving and extending SAGD performance by solvent addition to steam. The improvements include higher and faster drainage rates, lower energy and water requirements and reduced green house gas (GHG) emissions. The Thermal Solvent Hydrid process focuses on combining solvent with a small amount of steam in a VAPEX (vapour extraction) process (3)(4) . This process offers the potential of higher rates than cold solvent VAPEX at less energy consumption than SAGD.Hybrid steam-solvent processes, when fully developed, will extract oil at lower cost than SAGD and will also open currently marginal resources for exploitation, increasing oil reserves. This paper presents and discusses the principal concepts and key parameters for the new hybrid steam-solvent processes and compares expected performance to SAGD.

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TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractIn this paper, a new contractual agreement is proposed for the development of marginal oil fields in the Nigerian prolific hydrocarbon sedimentary basins. The proposed agreement is a modification of the existing agreements taking into consideration the special nature of marginal oil fields. Detailed economic analyses were carried out to assess the feasibility of the agreement. The economic analyses involved cash flow modeling, project profitability analysis, project sensitivity analysis and risk modeling using available and generally accepted economic, financial and technical data about the Nigeria operating environment. The final results from this study show that investing in the development of Nigerian marginal oil fields is a worthwhile option. The results show that the proposed agreement leads to favorable return on investment for all the parties involved. Project sensitivity analysis shows that if the combined cost of seismic survey and signature bonus is increased by more than 10%, the project becomes uneconomic. Also, if the price of oil falls below US$18.07, the project would have to be re-evaluated because the discounted pay back period (DPBP) would exceed the expected project life. Furthermore, risk analysis shows that as the NPV (net present value) increases, the risk level associated with such NPV also increases. Options available for financing marginal oil fields development are also presented.