A dry hole is used to describe an exploratory or development well that has not yielded a significant amount of oil and gas.
How it’s important to us
Drilling a well that ends up not being fruitful (no commercial value) can considerably impact the return on capital invested. However, a dry hole doesn’t necessarily mean failure. They are considered as operational risks (almost inevitable) and it remains crucial to E&P companies to have a comprehensive set of strategies to mitigate these risks such as investment diversification, the use of latest drilling technology, etc.
These are the most frequent causes of dry holes:
- The absence of trap in the reservoir rock: This may be due to (i) miscorrelation of stratigraphy at the sub/surface mapping, (ii) mistakes in surveying the elevation the derrick floor, (iii) misinterpretation of the topographic relief.
- The absence of a reservoir rock: the well reservoir may have faulted-out, lost its permeability, or not been reached.
- The absence of oil or gas in the trap: the reservoir rock may have been eroded and the oil and gas slipped away or due to unfavorable conditions (i.e.: abundant organic materials), oil and gas have not been formed in commercial quantities.
- A lateral shift of the trap with depth.
- A deflection of the test well or
- A failure to recognize the pool during drilling: at a certain depth, the drilling mud makes it difficult to detect oil and gas formation