fax 01-972-952-9435. AbstractMany of the latest generation of ultra deepwater capable rigs included emergency BOP (Blow Out Preventer) control capabilities, sometimes referred to as secondary intervention systems. Such systems represent the last line of defense in containing a well. Should it be necessary and unavailable, the result could be environmentally and humanly catastrophic.Building on installations that have been in service for many years, these capabilities range in functionality and purpose, from providing an alternate means to operate BOP functions in the event of total loss of the primary control system to assisting personnel during incidents of imminent equipment failure or well control problems. They can be actuated automatically or manually, and utilize components of the primary BOP control system or be totally independent. With as many permutations as there were rigs built, an understanding of the capabilities and limitations that exist on a particular rig is of critical importance in assessing the risks associated with a drilling program.While there currently are no standard terms in use to describe the essential attributes of systems, this paper recommends definitions and terms for a common understanding. The defined terminology is then utilized to compare and contrast system parameters, identifying various system strengths and weaknesses for use in risk analyses.Possible enhancements to existing emergency control systems will then be discussed, as well as their benefits and anticipated costs. Finally, the paper will recommend best practices for moored rig operations and those for operations utilizing DP (Dynamic Positioning).

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractEvaluation and improvement of sweep efficiency are important for miscible displacement of medium viscosity oils. A high-pressure quarter 5-spot cell was used to conduct multicontact miscible water-alternating-gas (WAG) displacements at reservoir conditions. A dead reservoir oil (78 cp) was displaced by ethane. The minimum miscibility pressure for ethane with the reservoir oil is between 630 and 1000 psi. Gasflood followed by waterflood improves the oil recovery over just waterflood in the quarter 5-spot. As the pressure decreases, the gasflood oil recovery increases in the pressure range of 660-1380 psi for this undersaturated viscous oil. WAG improves the oil recovery in the quarter 5-spot over the continuous gas injection followed by waterflood. WAG injection slows down gas breakthrough. A decrease in the solvent amount lowers the oil recovery in WAG floods, but significantly higher amount of oil can be recovered with 0.1 PV solvent injection over only waterflood. Use of a horizontal production well lowers the oil recovery slightly over the vertical production well during WAG injection. Sweep efficiency is higher for lower reservoir pressure (in this undersaturated oil), for 9-spot pattern, and for 1:1 WAG injection compared to continuous gas injection followed by waterflood in the 5-spot model.

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