Subsea Well Intervention in the North Sea - Learning from Mistakes and Experience
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BP Norway is well versed in well intervention from fixed platforms. The present Skarv field development will however require future subsea well interventions to take place from different floating vessels. BP has extensive experience from subsea fields outside of Norway, and it is necessary to ensure that the planning and preparations for such activities in Norway are fully up to speed with company competence. This thesis seeks to act as reference work for anyone interested in learning about subsea well intervention in BP Norway, but should not be mistaken for purely theoretical work. The overall goal is to assess how future subsea well intervention operations on Skarv can be performed, optimised and incorporate all BP learning from previous operations in the North Sea, thus contribute to increased hydrocarbon recovery from the Norwegian continental shelf. In order to properly prepare the well intervention department and management systems for the coming challenges, a broad definition of subsea intervention practices, technology and experiences have been described. Subsea wells are expensive to intervene with conventional rigs so the more cost-effective Light Well Intervention (LWI) alternative has been selected as a focus area. Even LWI vessels are expensive machinery so malpractices during operational execution may compromise the good economics of well interventions. The in depth study is focused on experienced unplanned events causing delays or non-productive time (NPT) during operations and thereby reducing operational efficiency. A powerful tool to increase the operation factor (uptime vs. downtime) and economics of subsea interventions is to proactively apply risk management techniques, hence this subject is also incorporated in the in depth study. The thesis is operationally orientated and a wide range of real data has been analysed, including but not limited to operational daily reports, end of well reports, after action reviews, risk assessments, operational guidelines, procedures, practices and investigation reports. The BP advisory team was consistently involved in the process and in addition to analysing documents, expert interviews were conducted. The analysis is by reasoning of the above concentrated on all operations conducted from the three LWI vessels BP had in operation in the North Sea in the time period 2009-2011. One of the most important findings is that around 80 % of all lessons learnt stems from ?Planning?, ?Equipment? or ?Operations?, suggesting this should be the main arena for organisational learning focus and future improvement efforts. Among a number of comparable reports, the following example from the LWI vessel Island Constructor operating on the Devenick field in 2011 has helped in narrowing down one of the key causes behind the high number of incidents within the ?Equipment? and ?Operations? categories to interface clashes: ?Unable to land off tree running tool on the subsea tree due to interface issues between the hydraulic couplers. Various attempts to land the tree running tool anyway lead to wear on equipment and 3 coupler shrouds came free.? Several similar underlying causes have been identified based on commonalities found when cross referencing all the subsea intervention operational lessons for different phases including ?Planning?, ?Rig Up?, ?Personnel?, ?Communication? and ?Miscellaneous? in addition to the above mentioned categories. Some of the documented lessons learnt are repeated at other vessels later in time, questioning the ability to actually benefit from recording these lessons. A recommended risk assessment template has been established in order to assist focus for future planning of similar operations in Norwegian waters. Implementation of the template will improve operational efficiency, reduce unwanted downtime and make BP among the ?best in class? when it comes to practical risk management and organisational learning within subsea LWI operations. Further work should be done to include an even more comprehensive data study to uncover trends that might have gone under the radar. Further work should also focus on providing an effective permanent organisational learning platform to ensure unwanted events do not repeat themselves and that all relevant lessons learnt are indeed incorporated in future operations to be able to take full advantage of previous successes and failures. All BP experiences should be gathered and processed to get a total experience and risk data bank for these operations. Recommended measures from the risk register should be transformed to updated programmes and procedures. Further work should also seek implementation of the new recommended risk register approach proposed in this thesis for subsea well interventions in the BP organisation.