Use of Realistic Geomodels and Synthetic Ultra-Deep Directional Resistivity Inversion in the Pre-job Planning of a Horizontal Oil Production Well
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The aim of this thesis is to test a workflow to improve subsurface understanding by building and updating realistic geomodels for a horizontal well in the Norwegian Continental Shelf (NCS). The focus is on pre-job planning for a well placement job based on logging while drilling (LWD) and surface seismic survey, where the ultra-deep electromagnetic (GeoSphere tool by Schlumberger) measurements link the LWD measurements to the seismic. By using the Compound Earth Simulator (CES) software, developed by Statoil ASA, a set of realistic geomodel scenarios are constructed based on the offset well information, the existing geological concept and seismic data interpretation. The synthetic ultra-deep resistivity inversion images are generated, by forward and 1D inverse modelling, and are then studied for potential pre-drilling scenarios. This summarizes the pre-job planning phase. These geomodels assist in the evaluation of the uncertainty before drilling. A better understanding of the subsurface and reservoir conditions by these pre-job models and their inversions, assist in the interpretation of features such as the top of reservoir, fluid contacts, flooding in layers and formation structures at the time of drilling and therefore, improve real time geosteering decisions. Any variations in the expected geological features that may be encountered at the time of drilling can be compensated for, more swiftly, with these pre-job models available on different scenarios. Thus, make the operations robust and achieve optimized well placement.