f Column Height Guidelines for Undrilled Prospects in the Southern Gulf of Mexico (GoM)

Pelagic shale seals of the Gulf of Mexico are known to form excellent seals but how do you estimate a range in column height assumptions for a high relief undrilled prospect in the GoM?

The underlying principle of top seal integrity is related to Effective Stress and hydrocarbon buoyancy and seal capacity can be estimated from a knowledge of expected hydrocarbon phase and reservoir pressure conditions.

In the absence of this type of constraining data, a study of field analogues is revealing in terms of separating column heights that are due to topseal integrity versus fill-to-spill trap geometries. Plotting column height versus overburden depth is also surprising in how the largest column heights are related to traps that lie only 1000 – 1500 meters below mudline. These observations and their likely reasons are discussed in relation to key fields of the Southern GoM and conclusions are drawn for predicting column height in undrilled prospects plus some pitfalls to watch out for.