senegal and csem

Just a cautionary note here. CSEM is an interpretive tool, just like seismic, and it works well in some areas but it's a long way from actually drilling a well and testing a prospect. In some areas it just doesn't work and in many areas, its results are ambiguous. Whereas sesimic looks at reflections from rock layers, caused by density differences, CSEM looks at the resistivity contrasts in the rocks, which can be caused by hydrocarbons. Problems may occur if there are resistive rocks nearby such as limestone or salt (or a few others). A USGS publication on Senegal shows a cross-section running near the FAR acreage and the limestone stands out pretty clearly. It's very possible that this made the data too 'noisy' for confident interpretation, at least for Shell. Shell's appetite for risk tends to ebb and flow. We don't know what acreage was competing for funding but you can be sure it was pretty good - Shell don't waste their time exploring poorly prospective acreage. Shell's exit is a setback, for sure but it shouldn't be viewed as too damning.