Capturing By-Passed Pay
Pay is the thickness of a reservoir rock that contains significant quantities of potentially exploitable hydrocarbons. By-passed pay relates to movable hydrocarbons that cannot be drained by existing wells and will be left in place if nothing is done. By-passed pay can occur at wells or between wells. In the former case it might literally have been overlooked at the time that the well was drilled and completed. This might have happened because the pay was “hidden”, as for the infamous low resistivity pay, or perhaps because the hydrocarbon was gas, for which there was no ready market at the time. In between wells, integrated reservoir studies can show that reservoir zones or layers have been left untapped during field production. This might have happened because of a preferential watering out or because discrete sand channels were not intersected by a wellbore.
This presentation looks at diverse examples of by-passed pay and summarizes the approaches that are being used to capture them. By-passed pay constitutes a lower-risk prospect than hydrocarbon accumulations in unappraised areas. Beyond this, there are three drivers. First, new technology in the form of improved reservoir imaging allows insights that were not achievable previously. Second, an evolving understanding of how reservoirs work has allowed procedures to be developed for maximizing the exploitation of even problematic accumulations. Third, market forces amid global post-peak-production fears are giving the exploitation of by-passed pay an even greater impetus today. Some pointers are identified as an aid to maximizing commercially recoverable hydrocarbons in developed assets.