The 48/l 7b-G2 well was the second and final development well on Guinevere; a UK Southern North Sea Rotliegendes gas field.

Guinevere is an aeolian reservoir developed within a faulted anticline with a partial gas column. A horiwntal well as the primary prod ucer was deemed necessary to avoid water influx problems.

The surface location was constrained by the existing vertical well. Optimisation of the bottom hole location and reservoir target was achieved by integrating analysis from a variety of disciplines. The location of the horiwntal section was determi ned by considering the following factors: The thickness of the gas column was prognosed using geostatistical depth conversion methods based on 30 seismic. This was integrated with fault detection and seismic amplitude as an indicator of reservoir quality. Additionally the target horiwn was derived from a detailed geological model and the orientation of the internal reservoir heterogeneity determined the optimum well orientation. Potential interference of the existing vertical and horiwntal wells also influenced the location of the G2 well.

Drilling constraints placed limits on our ability to satisf y all of these requirements.

A well location was chosen which satisfied most of the above considerations. This involved a 160 degree left hand turn in the borehole trajectory. In early 1993 the well was drilled to the chosen location and a 3500 ft horizontal section was successfully completed. The well has proved to be the most prolific in the Lancelot complex.

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