Spotfire: A new workflow of stress visualization for Statoil Rock Mechanics Department, combined with interpretations of minimum horizontal stress data from the Norwegian Continental Shelf
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For many years it has been performed formation stress tests (FST) on the Norwegian Continental Shelf (NCS). These tests are performed for estimating the formation strength in wells. More strict regulations for well integrity on the NCS have led to a need for better and more precise treatment of the FST. Minimum formation stress is by NORSOK the preferred parameter as the well barrier (reg. fracturing) during drilling, production and permanent plugging and abandonment. To estimate this parameter extended leak off tests (XLOT) are the preferred method. Statoil ASA has performed several XLOT`s the last years (ca. 100). The information from these tests is gathered in a spreadsheet (StressAtlas) where some of the different parameters from each tests are structured together with general well information. One of the goals in this master thesis has been to structure these tests in a tool named Spotfire. This is a tool with capacity of handling large datasets. An additional usage is to analyze in great scale the different data and place them in their regional area with the help of coordinates. One of the challenges with this task is to gather all the needed information from each test. All data is not stored in StressAtlas, some of the information is stored in other databases. With Spotfire this problem can be solved by the use of SQL codes that connect the data from different databases.Another part of the task is to use the designed tool for interpretations and calculations. Regional differences of the minimum formation stress on the NCS have been analyzed and discussed. Overburden parameters as vertical stress and pore pressure influence on each of the regional zones have also been discussed by calculating the effective stress ratio for each of the tests. It has also been designed a universal equation for the NCS that can be used for estimating the minimum horizontal stress with depth and pore pressure as an input. Regional differences have been observed and it has been developed an equation for estimation of minimum horizontal stress on the Norwegian continental shelf that has a higher accuracy than previous equations.