Technology Today Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering.     Abstract Drilling high-pressure/high-temperature (HP/HT) exploration wells remains a challenge, despite years of experience acquired by the drilling/completion industry. Development wells have further expanded the envelope of performance of the technologies and procedures required to deliver production from HP/HT fields safely and economically. Now comes the time of drilling and completing infill wells, which paradoxically appear to be more difficult as depletion increases and the mud-weight window (MWW) diminishes.   To overcome this problem, intense engineering work has been carried out to better understand the effect of the depletion on compaction and fracturing gradient, to design and qualify new drilling-mud systems combined with stress-caging techniques, and to prepare contingent solutions with the deployment of expandable- and drilling-liner technologies.   Three infill wells have been drilled, completed, and put on production by Total in the Elgin/Franklin fields on the UK Continental Shelf. This success was achieved through severely depleted reservoirs—with depletion greater than 800 bar—and has enabled phased HP/HT developments and deep exploration beneath depleted horizons.   Overview of the Elgin/Franklin Extreme-HP/HT Fields The Elgin/Franklin fields present an extreme combination of pressure and temperature (1,100-bar virgin pressure and 200°C, respectively) and remain the largest HP/HT gas/ condensate fields developed in the British sector of the North Sea. The fields are approximately 200 km northeast of Aberdeen in the Central Graben area. Following discovery and appraisal from 1985 to 1994, development started in 1996 with two unmanned wellhead platforms tied back to a central production facility. Eleven wells were drilled and put on stream, with deviations up to 50°, in an average drilling duration of 120 days. These wells were drilled before a predefined limit of depletion level had been reached, a level at which the MWW closes—calculated for Elgin/Franklin as 100 bar. First oil production occurred in 2001. Later, two satellite structures, Glenelg and West Franklin, were drilled and put on production through the existing installations in 2006 and 2007, respectively, (Fig. 1).   The reservoirs consist of Jurassic sandstones buried at a depth exceeding 5300 m. The primary reservoir is the Fulmar, also called Franklin, sands. Reservoir fluids are gas/ condensate with a bottomhole pressure of 1100 bar and temperature of 190°C. The Fulmar reservoir is underlain by the Pentland reservoir with bottomhole conditions of 1150 bar and 200°C (Fig. 2). Despite the depth, the main reservoir shows significant porosity and permeability, allowing strong productivity. Up to 30% porosity and 1-darcy permeability are found in some Fulmar layers   Individual wells in the field can produce up to 3.5×106 m3/d of gas with associated condensate. Surface production conditions are 860-bar wellhead shut-in pressure with an associated temperature of 180°C. The produced effluent contains 3 to 4% CO2 and 30 to 40 ppm H2S. Initially, field gas production reached 14.6×106 m3/d, with 24 000 m3/d of condensate. This combination explains the strong need for technology and in-depth engineering for these wells.

In 2005, it was evident for Total E&P UK that the battle for incident free drilling and well maintenance operations would become more difficult, with activity booming, lack of experienced workforce and the arrival of a younger generation of recruits. In the mature operating environment of the North Sea, a new Safety initiative needed to alert offshore teams to hazards around them and without adding procedures on top of existing ones. The vision was to enhance risk awareness of newcomers who were not familiar with the hazards of the oil and gas industry and to refresh memory of the more experienced personnel through a paper and procedure less program. The drilling team's initial inspiration was the power of the black silhouettes displayed on roadsides where traffic accidents had occurred. The idea was to build our own silhouettes to display them on the drilling rigs, at locations where real or potential incidents had happened. Newcomers would immediately recognise hazards from the silhouettes and would learn details of the incident from an associated Safety Alert displayed on the provided "Shadows Board". The silhouettes stay in a given place for not more than three weeks for each Safety Alert, before being re-positioned. This is the dynamic aspect of the process. Contractors, as well as Operators, had collections of Safety Alerts which were gathered to construct a Safety Alert data bank which now contains around 1000 alerts, all laminated and part of the "Shadows Kit". Total E&P UK drilling and well maintenance team also produce its own Safety Alerts. After a Shadows pilot test of six months on 4 drilling units, early positive results indicated a significant reduction of high potential incidents. From these encouraging results, Exploration and Production branch's Drilling Division of Total extended the initiative to fifty rigs worldwide. The paper will detail how the project was handled with Contractors' participation and will present the outcome of the project in terms of Safety culture, learning organisation and performance achievements, as well as future perspectives. Introduction In drilling and well maintenance operations, as in other industrial processes, "full achievement" of complex and challenging projects is not possible, if the people are exposed to risks or hazards and subsequently are severely or fatally injured! In such instances, at the end of the project, there would be no cause for celebration and the project itself would lose all the attraction and challenges it had. This is "the very idea" that we have tried to embed in the minds of everyone working in Total E&P UK's drilling and well maintenance activities (i.e. Drilling Contractors and Service Companies). Despite previous efforts to address this issue, success had been quite limited. The "wall" that we needed to construct and reinforce "brick by brick" to protect our teams, has revealed itself to be a long and never ending process. In this huge task, everyone involved is invited to take responsibility to consolidate the "wall" where every single "brick" counts.

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