Trajectory control in directional wells essentially requires control of only two parameters: well inclination and well azimuth. However, always tighter economic constraints and the increasing complexity of well trajectories keep setting higher challenges that demand purpose-designed and cost-efficient solutions. The standard rotary drilling tools first used for directional drilling gave poor trajectory control. The subsequent addition of Variable Gauge Stabilizers (VGS) addressed only one side of the problem: control of inclination. Both inclination and azimuth were then mastered with Steerable Motor technology, which rapidly gained supremacy. However, there has been discontent with Down Hole Motors (DHM) for a variety of problems ranging from Rate Of Penetration (ROP), sliding mode, friction and lost-in-hole incidents to well tortuosity and hole cleaning. Jumping to rapid conclusions, one might thus think that that motors will soon be replaced by Rotary Steerable Systems (RSS). This evolution of directional drilling techniques has led to the development of more and more sophisticated tools integrating electric and/or hydraulic power systems and loads of "embarked" electronics. The related expenditures have driven service costs to levels that are very often prohibitive for standard drilling programs and/or environments. This paper introduces an innovative technical solution that makes it possible to control both azimuth and inclination using standard rotary Bottom Hole Assemblies (BHAs). It is based on a patented concept permitting command of Bit & BHA walking tendencies through downhole friction management at the level of a "strategic" string stabilizer. On the basis of this concept, a joint industry project led by TotalFinaElf has successfully designed, built and field-tested a first prototype - the "Gyrostab". This missing link in the evolution of directional drilling announces the birth of a new generation of standard rotary drilling tools. Introduction: A short history of directional drilling From the early 1930's into the 1970's, expertise in trajectory control was in large part devised and developed in the "tally book" of directional drillers. Using rough and unreliable directional drilling tools without any continuous measurements, their very exhausting task at the time was to control trajectories single shot after single shot, relying more or less on "feeling" to anticipate what might happen down-hole. Motors for directional drilling were still in their infancy (the first DHM appeared in 1955), and standard rotary drilling was used on a very large scale (Figure 1). However, the challenge for drillers was lightened by the fact that directional well trajectories were simple (2D, J or S shape wells, with moderate inclination values), and long runs were out of the question in any case because of bit life. Towards the end of this period, DHMs and bent subs were employed only to initiate the kick-off. Rotary BHAs were used to complete the build-up section and the following slant and/or drop-off sections, with short motor correction runs to put the well-path back on track when necessary. Left alone the rest of the time, the azimuth would drift by more than 1 degree per 100 feet in some cases, especially when using rock bits.

No abstract

To improve the quality of well planning and decrease the risks involved in drilling complex wells, E&P companies have been focusing during the last decade on collaborative work of asset team. A new workflow consisting in separating multidisciplinary feasibility evaluation from detailed engineering has now been used on several projects. This workflow decreases dramatically the necessary cycle time to plan a well since only those alternatives that are viable for all disciplines are going through detailed analysis. The angle block of this method is the combination of a shared earth model with advanced three-dimensional visualisation techniques and quick, but precise evaluation tools. The use of constraints to define default values makes it simple to plan targets and wellbores only with 3D interactive graphic editing. Those constraints can themselves be relative to the structural geological model. Therefore the generated design is accurate enough to be trusted when used by the various evaluation functions. To assess the value and feasibility of a target/well solution, the asset team can use interactively drainable volume, wellbore position uncertainty, driller's target, wellbore collision and drillstring mechanical calculations.

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.

With the current market's high prices for drilling units and sophisticated directional and formation assessment services, low systems reliability or poor directional performance in the execution of complex wells (ERD, HPHT, Deep Water applications) can spell costly Non Productive Time (NPT) for operators. Over the past two decades, many Bottom Hole Assembly (BHA) models have been developed to address the directional performance issue, but their application in an operational environment has generally failed for lack of strong associated BHA analysis methodologies. This paper presents a unique automated methodology for Post Analysis of BHA directional behaviour. It is based on modern 3D analytical models, combining BHA, BIT and formation effects with highly flexible data management. Implemented in user-friendly BHA management software, it can be used to define a BHA run segmentation and to determine the influence of the BHA settings in particular geological formation blocks. The Post Analysis clearly displays the final results of the BHA (objectives and performances versus prediction window), highlighting any problematic intervals drilled. Already, the methodology has solved challenging directional performances issues, generating significant savings and optimising the learning curve process. The field applications referred to in the paper have demonstrated that, without a proper methodology, a model offers little added value. The examples discussed here from Total E&P affiliates deal respectively with Rotary, Rotary Steerable System (RSS) and Steerable Motor (SM) directional BHAs. Case studies have led to BHA and bit design modifications. The results were well beyond expectations, ensuring good well positioning through the reservoir by improving BHA stability and manoeuvrability. Efficient drilling (reduced sliding, improved hole quality) was also achieved with a single SM BHA in 17 1/2" applications during kick-off, and successive build-up and slant drilling intervals. The methodology and its associated BHA Management® software have proved an undeniably valuable tool for the drilling community. The model is also run at the well Pre Engineering stage to check BHA design proposals by making multiple sensitivity analyses and by fine-tuning solutions to the operational context. Finally, in an industry with high personnel turnover, the software's global data management system ensures good capitalization of know-how and ongoing learning curve benefits. Introduction Historic In the 1980s, driven by the constant improvements in bit life and breakthroughs in Measurement While Drilling technologies (MWD), engineers began to introduce "science" into what was then the exclusive preserve of directional drillers in order to gain a better understanding of the way rotary BHAs behaved. Until then, experience was mostly confined to personal tally books and the upshot was inconsistent directional well trajectories and usually short BHA runs - in the region of 150 to 300 m. The early stages of the technological revolution in I.T. opened the doors to R&D efforts at developing 2D1,2 (hole inclination prediction only) or 3D3,4,5 (hole inclination & azimuth predictions) BHA model software. These tools modelled BHAs as beams supported by contact points (collars - stabilizers - hole contact). Their main outputs were: BHA deformation & side forces at contact points with the hole and at the bit. Two modelling schools co-existed, one relying on the side force developed at the drill bit (magnitude and direction) and the other imposing hole curvature in the same direction as the side force at the drill bit to neutralize it, introducing the equilibrium curvature concept.