An improved process for decreasing the permeability of a subterranean oil-bearing formation which comprises injecting an aqueous surfactant solution containing a chemically crosslinkable, water-dispersible polymer which prevents the surfactant from foaming until it is in the formation and after the polymer breaks down due to heat in the formation caused by steam which is used to carry the aqueous solution into the formation. In accordance with one embodiment, gelled or ungelled cellulose ether polymers in an aqueous surfactant solution are injected with steam into the more permeable or more depleted portions of a subterranean oil-bearing formation to produce a selective blocking due to the formation of foam in the more permeable sections of the formation which forces the remaining injection steam to produce oil from less depleted portions of the formation.
Thermally stable foamable gelled compositions suitable for post-primary oil recovery e.g., steam- or gas-foamed systems comprising water, a surfactant, a polymeric viscosifier, an aldehyde component, and at least one phenolic component such as resorcinol, catechol, and the like, as well as selected oxidized phenolic materials such as 1,4-benzoquinone of natural or synthetic origin and natural and modified tannins. The gel compositions can additionally contain gel stabilizers such as sulfomethylated quebracho (SMQ) and chemical buffering agents such as sodium bicarbonate.
Thermally stable foamable gelled compositions suitable for post-primary oil recovery, e.g., steam- or gas-foamed systems comprising water, a surfactant, a polymeric viscosifier, an aldehyde component, and at least one phenolic component such as resorcinol, catechol, and the like, as well as selected oxidized phenolic materials such as 1,4-benzoquinone of natural or syntheic origin and natural and modified tannins. The gel compositions can additionally contain gel stabilizers such as sulfomethylated quebracho (SMQ) and chemical buffering agents such as sodium bicarbonate.
Thiourea functions as a solution viscosity stabilizer in aqueous compositions comprising thiourea, nonionic polymers such as polyalkylene oxides and anionic surfactants such as petroleum sulfonates. The aqueous compositions are useful in connection with fluid-drive oil recovery processes, processes for drilling, completing or working over wells, or the like processes in which a thickened fluid is injected into or brought into contact with a subterranean earth formation.
A process of treating a plurality of wells involved in an enhanced oil recovery process so that oil and/or gas can be displaced from a reservoir in a more uniform manner comprising treating the formation surrounding and in the immediate vicinity of each well involved in the process with a solution that sets with time to form a plug in the more permeable zones of the reservoir surrounding each well.
A noncondensible gas is used to preheat a portion of a permeable strata prior to plugging thereof by steam containing a surfactant. Once the desired portion of the permeable strata is plugged, steam without a surfactant is utilized for production of oil from the less permeable oil-bearing formations.
