No abstract

In the exploration and production (E&P) industry attempts at reducing the cost of the well construction by applying various well architecture slim designs has attracted attention from operators for decades. The recent industry downturn has further contributed to a renewed focus on this strategy. In this study we present a slim well design application within the FortunaCo project (a Joint Venture between OneLNG and Ophir), which aims at developing the Fortuna and Viscata fields in Deepwater offshore Equatorial Guinea. An advanced static nonlinear Finite Element engine is used in this process, which considers contact and friction; can handle large deformations and is therefore suitable to carry out buckling analysis. The top hole structural robustness is analyzed using this engine in the event of a worst case axial load, which for this study is assumed to be:The Conductor Pipe (CP) able to take its own weight only,The upper section of the surface casing (inside the CP) free of cement,The full buoyant weight of the Horizontal Christmas tree and Subsea Blowout Preventer applied onto the well. This paper demonstrates that the selected numerical model is suitable to estimate critical buckling loads and identify post-buckled modes exerted on surface structural casings. Furthermore, it is shown that the visualization capabilities and speed of the engine allow the operator to optimize the design iteratively in an efficient manner. We conclude that the selected methodology is suitable for the operator to validate a slim well design for a Deepwater development application at concept phase for minimal cost with the necessary level of confidence.

Prior to undertaking any drilling campaign, the process of offset well analysis is of paramount importance. When performed accurately and presented properly it provides the basis for all design work and risk analysis. A new feature in the modelling software Petrel called Drilling Risk Manager offers the ability to be able to carry out the offset well analysis in a 3D environment. The aims of this study is to investigate the means in which the Drilling Risk Manager feature of Petrel can aid in de-risking wells during the offset well analysis process and to highlight the potential efficiency savings that can arise. The efficiency savings of using Petrel have been highlighted through the use of a case study focusing on the initial development work that was carried out in conjunction with TAQA for their North Cormorant and Cormorant East fields in the UK continental shelf. In this study a Schlumberger engineer worked closely with TAQA on classifying the offset well data for the field, populating the data into a 3D shared earth model in Petrel and then using this model to perform a full risk analysis. For TAQA, using Petrel has made it easier to clearly view all of the drilling hazards that have occurred on the North Cormorant and Cormorant East fields. Using all of the extra information, two wells drilled on the Cormorant East field were well prepared for hazards which are common in the area. Using the 3D model to aid in the risks analysis process saved a considerable amount of time in comparison to the usual method employed by TAQA. Schlumberger are in the process of fully developing the use of Petrel as a means of derisking wells in mature fields in to a value added service that can be provided throughout a drilling campaign. Projects are being developed for several UK Operators in this field, incorporating well bore stability and drilling analysis in order to provide efficiency savings throughout a drilling campaign.