Horizontal wells often cut down and up the stratigraphy in order to maximise reservoir exposure in a particular layer or reach more than one target. Faults may be encountered and these can be detected by changes in lithology and measured with dipmeters or image logs. Some of these faults may be seen on seismic while others will be below seismic resolution and be unpredicted but may require the wellbore to be adjusted up or down to stay in the target reservoir layer. These minor faults can also form baffles on a production time-scale and may affect completion strategy.
It is possible to generate a local surface from a combination of dip data and intersections of various layers in a known stratigraphy.
Once the interpretation has been completed, soon after drilling of the borehole, it is useful to be able to download these local surfaces to mapping and modelling packages. This assists in avoiding the loss of useful information gained when the well was drilled, but which can be easily lost before the field is re-mapped some years later.