Over the recent years, the oil industry has been drilling wells in ever increasing water depths. Drilling these deepwater wells is performed under specific conditions namely a combination of extreme thermodynamic conditions (low temperature and high external pressure at the mud line level) and a narrow margin between pore pressure and fracturing pressure. These conditions lead to a number of drilling difficulties, especially in terms of well control. Traditionally, these challenging wells are drilled using a sub-sea BOP stack connected at the mud line with a low-pressure riser to the surface. From a well control point of view, this configuration presents several limitations: BOP closing time may be long enough to allow part of the influx to migrate inside the riser, long kill and choke lines add significant friction losses which sometimes jeopardize the kick control, BOP components are subject to extreme thermodynamic conditions and therefore are prone to frequent failures which increase drastically the rig NPT. In an attempt to overcome the drawbacks of using a sub sea BOP stack and reduce the costs associated with an expensive rig package, the industry developed a technique using the BOP stack on surface in a "jack-up type" configuration and a high pressure drilling riser. Primarily used in the Far East, this technique presents certain limitations, the main one being the absence of a secondary barrier at or just below the mud-line in case of riser failure. Total was considering to use this technique in 2000m water depth on its recently-acquired Donggala deepwater block, offshore Mahakam straight, Indonesia. A Quantitative Risk Assessment on surface BOP stack drilling was performed. This highlighted the necessity to have a shut-off device at the mud line level in order to reduce the environmental impact in the event of riser failure. Total, in association with Cameron, designed and developed this sub sea shut-off device (hereafter referred to as ESG - Environmental Safe Guard) and with Transocean upgraded a rig to allow safe and efficient drilling on the Donggala block. This paper outlines the development of the ESG in parallel with the required riser design and well architecture as an alternative to deepwater well construction. An operational feedback on the successful running of the ESG is provided. Introduction Over the past several years, the industry has developed a technique allowing deepwater wells to be drilled with a semi-submersible drilling rig and the BOP located at surface. Drilling with surface BOP stack presents a certain number of advantages compared with traditional sub sea drilling, such as:Cost saving: drilling within 2000m of water and a sub sea BOP stack usually requires the use of a 5th generation drilling rig with typical day rate rising up to 200,000US$/day. This generates very high total well costs. The surface BOP technique allows the use of 3rd generation drilling rigs with lower day rates (typically 80,000US$/day) and thus the potential for lower well costs. Reductions in high mob / demob costs are also possible especially for deepwater locations remote from the traditional operating areas of the 5th generation rigs.Optimize drilling operation: The potential to save rig time as no time is spent running and pulling the BOP together with the riser in deep water.Reduce Non Productive Time: having the BOP at surface actuated by a simple control system reduces the risk of BOP failure resulting in significant downtime to pull the BOP to surface for repair and re-run it to the mud line.Well control situation: the kick or well control situation is simplified by not having several kilometers of choke / kill line (and their corresponding high frictional pressure losses) while applying the simpler surface BOP well control techniques.

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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In 2002, TOTAL E&P management requested all the different divisions to implement actions plans to improve the HSE performance of the company. The purpose of the paper is to present and discuss the HSE Performance of the drilling activity during this 3 years period through the examples of 2 different affiliates in Indonesia and Gabon. TOTAL Indonesia has gone through an impressive increase of its activity (100 wells drilled per year) over the last 3 years, with the arrival of 5 drilling units (total of 9 drilling units on relatively long term contracts). On the other hand, TOTAL Gabon is a mature affiliate, trying to extend the production plateau by performing re-entries on existing production installations during short term drilling campaigns. The first part of the paper will present the particularities of the drilling activity on the different fields, the HSE context and organization, and the objectives set by the management. The second part will establish an interesting comparison between the road accidents statistics in France and the accidents on the Indonesian drilling units. It will highlight the existence of the well known plateau which is reached and how it is reached. A selection of site examples (both from the previously mentioned Asian and African affiliates) will illustrate the various statements, and the distinction between hardware improvements (technical modifications, new equipment...) and soft improvements (procedures, safety meetings, hazards observation programs...) will be established. The conclusion will discuss the fundamental question of the continuous improvement of the HSE Performance, in particular how to go beyond the plateau. Based on the analysis of this 3 years long intensive drilling period, it will present the 4 achievable objectives that should be given to an individual rig in a context where a "Zero Accident" workplace is the ultimate goal, but unfortunately still a concept. Introduction The drilling industry has evolved a lot in the last forty years, not only from a technological point of view but also from an HSE point of view. Nowadays, it is a common practice to drill extended reach wells or long horizontal drains navigated in thin reservoirs with high accuracy, not even talking about exotic trajectories necessary to drill on congested declining fields; however, an equally impressive progress was made on the protection of the workforce, thanks to the change of mentality and the ever growing legal environment. A 21st century drilling site, whether offshore or onshore, has nothing to do with what used to be the standard forty years ago: the impact on the environment is taken care of right at the pre-engineering phase and the protection of personnel on-site during the whole life of the drilling project is of highest importance.