As the oil and gas industry matures, so does its technology and equipment. As a drilling rig gets older, it becomes increasingly challenging to use it to explore for untapped deep reserves. Offshore rig builders are constantly manufacturing rigs with new, sophisticated capabilities, thereby widening the technology gap between the new rigs and the aging ones. As a result, many operators of older rigs are modifying their rigs to compete with newer ones. Using a modified second-generation semi-submersible rig in Indonesia, Total was able to reach target depth in an ultra-deepwater well by deploying a combination of surface stack drilling technology, a subsea shut-off device known as an environmental safe guard (ESG), and solid expandable tubular technology. If conventional casing had been used, the optimal hole size at total depth (TD) would have been impossible to attain and economically unfeasible without the use of a fourth or fifth generation semi-submersible or drillship. This paper describes the safe and successful integration of new technologies that enable surface stack drilling with modified second- or third-generation semi-submersible rigs in environmentally less-benign areas, including the Gulf of Mexico. In addition, the paper will discuss the deployment of solid expandable tubular technology from a modified second-generation rig and show how this technology enabled the operator to achieve a sufficient hole size at total depth while maintaining an economically viable operation. Introduction It is rare to see innovative oilfield technology that gives renewed life to equipment that has been surpassed in size and capacity, but that is what the wedding of three new technologies is doing. The ESG is a means of closing a well and disconnecting if a riser failure occurs. It works as part of a system with the surface stack/riser system and certain second- and third-generation rigs. (It should be noted that not all second- and third-generation rigs can be outfitted for surface blowout preventer (BOP) operations.) Unocal Indonesia is a pioneer of surface stack drilling with second- and third-generation rigs in deep water, and they have been successfully using this method for some time. When adding the ESG device and solid expandable tubular technology to proven surface stack drilling technology, a synergy emerges. The combination of these three technologies enables an operator to drill a wellbore to TD in ultra-deep water that would have only been possible previously using a fourth- or fifth-generation rig. After several successful implementations, this combination of new technologies and smaller rigs is proving to be a reliable means of reducing drilling costs in ultra-deepwater locations. Surface BOP Operation Simply defined, surface BOP operation is the practice of utilizing a floating drilling unit fitted with a BOP that is suspended above the waterline in the moonpool area. The BOP, usually a land/jackup type BOP, is connected to a high-pressure riser serving as a conduit to the sea floor (Fig. 1). Typically, the high-pressure riser is 13–3/8 in. casing deployed in one continuous length from the casing shoe to the surface wellhead. The equipment configuration is similar to a jackup utilizing added top tension, with the exception the vessel is floating and the water depth may be thousands of feet deep. While Surface BOP drilling is not a new concept, the technology to take the concept into ultra deep water began about seven years ago offshore Indonesia1. The surface BOP concept for this program was initially deployed to drill inexpensive exploration wells in a benign environment in water depths between 100 and 500 ft. The operation was successful and proved that several days time could be saved compared to conventional subsea operations. The concept was further refined to go into deeper waters to utilize the same cost savings found in the relatively shallow water. The factors contributing to lower per-well costs in a relatively benign sea conditions include the following2:A mooring system using a taut wire type mooring can go into greater water depths than normal.A pre-laid mooring system significantly reduces the time required to move the drilling unit between locations.

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Solid expandable tubular technology has achieved gradual acceptance in diverse regions worldwide since its commercial introduction over four years ago. Although there is still reluctance among operators to commit to preplanning this technology in their wells, others recognize the value of using solid expandable tubulars on a contingency basis. These innovators are embracing it as a method not only to overcome challenges and achieve the well objectives regardless of environmental circumstances but to achieve these goals using an economically viable, repeatable method.Recently an operator with wells in three different challenging regions of the globe deployed solid expandable tubular technology in each well. In West Africa, the requirement was to isolate a casing leak and return a damaged well to production. The challenge in the Asia Pacific region was to drill a deepwater exploration well using surface stack deepwater drilling technology. In Texas, the operator isolated ballooning shale so that the 7-in. conventional casing could be set at target depth to retain projected hole size. In diverse challenges, solid expandable tubular technology provided the operator viable, value-driven options that were not available using conventional casing and technology. This paper will present the challenges one operator faced in three global regions, discuss how solid expandable tubular technology overcame the challenges presented by these environments, and created an economically-viable solutions. The diversity of solid expandable tubular technology as it continues to gain acceptance within the oil and gas industry will be also demonstrated.