Carbonates underpin some of the largest oil and gas fields in the world, but also some of the most complex challenges to ensure a long-term sustained production of the hydrocarbons.
Where significant faulting or dissolution creates favorable flow paths, surrounding rock volumes with much lower permeability can be bypassed, requiring targeted infill drilling to drain stranded reserves.
While significant fracture systems can facilitate a rapid drainage of the reservoir formation, they can also be a conduit for water breakthrough, compromising the wells in the vicinity of the fault. Identifying the location of such faults makes it possible to plan a drilling program that would avoid the fault areas and reduce the risk of premature water breakthrough.
High permeability streaks
Dissolution frequently affects carbonate formations, either through weathering and formation deterioration when the formation is exposed to the elements or through water circulation at depth. Either way very large volumes can be in the form of substantial, connected voids that later fill with loose rock or gravel, and very high permeability.