gge for dummies, page-35

Timely1, this passage might help you understand the various stability problems with drilling near a salt dome. Even though salt domes normally accompany a large amount of hydrocarbons, the varying pressures near the dome make it more difficult to drill near as opposed to the sandstone structures in shales.

BORE HOLE FAILURE NEAR SALT DOMES
Bradley, William B., Reed Tool Company
Copyright 1978, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
http://www.onepetro.org/mslib/servlet/onepetropreview?id=00007503&soc=SPE

The stability of bore holes is greatly affeced by the conditions of stress in the earth (in situ stresses). The greater the mean in situ stress and the greater the in situ stress difference (sigma - sigma ), the greater the problem with bore hole instability. The presence of a salt dome can significantly alter the state of in situ stress from the normally stressed condition and as a result, the stability of bore holes in close proximity to salt domes can be greatly affected.

Little work has been done on the prediction of in situ stresses in the formations around salt domes. However, some unpublished work indicates that important changes in the in situ stress state can occur. Indications are that regions near tie shoulder and the flanks of the salt dome can be significantly affected. In formations adjacent to the flanks of the salt dome the in situ stress in the hoop direction around the salt dome may be lowered significantly below the normally stressed value which occurs at some distance from the dome.

The reduced in situ hoop stress resulting from the presence of a salt dome can significantly increase both lost circulation and bore hole collapse problems. For example, initial wells drilled at some distance away from the salt dome may not experience either significant lost circulation or bore hole collapse problems. Whereas later wells drilled using the same drilling parameters may experience increased problems as the wells are drilled in closer and closer proximity to the salt dome. An example of the influence of salt domes on bore hole failure is discussed in the next section.