Page 380 - Numerical Analysis and Modelling in Geomechanics

RESERVOIR COMPACTION, SUBSIDENCE AND WELL DAMAGE 361

Figure 11.13 Well deformations corresponding to Well 551G.
deforms less than the rock. This is illustrated in Figure 11.17, in which the lateral
offset of the casing is plotted against the lateral shearing displacement prescribed
at the outside surface of the model. The slope of the plotted curve is less than 1.
0, showing that the casing displaced less than the prescribed shear. Figure 11.17
is the link between the wellbore scale and the field scale. The plot shows that the
slip computed from a field-scale model is likely to be overly conservative, that
is, field-scale models over-predict the true lateral offset of the casing. The results
of wellbore scale modeling shows that field-scale models, which do not include
the detail to account for the casing-rock interaction, cannot be used alone to
correlate casing damage with weak-layer slip or to subsidence.
The calculations of the field-scale model were compared with historical field
data. An extensive inspection of well workover records was conducted from the
files in the Section 33 operations. For the model discussed in this chapter, only