Selective placement of a permeability-reducing material in a subterranean interval to inhibit vertical flow through the interval

摘要

A process is provided for selectively placing a permeability-reducing material in an interval of a subterranean hydrocarbon-bearing formation penetrated by a well bore to inhibit the vertical flow of fluid between the well bore and an aquifer underlying the interval. The process is performed by simultaneously injecting a pair of fluids into the well bore, wherein one fluid has a density substantially less than the density of the other, and displacing the fluids out into the interval. The two fluids directly contact one another as they are displaced, however, the density difference between the fluids causes the first fluid to preferentially enter an upper portion of the interval and the second fluid to preferentially enter a lower portion of the interval under the force of gravity stratification or gravity segregation. The second fluid is aged in the lower portion of the interval, transforming it into a permeability-reducing material that substantially inhibits vertical flow between the aquifer and the well bore.