Weak gel system for chemical enhanced oil recovery
AssigneeEcolab USA Inc.
InventorsMichael L. Szalai, Mei Liu, Kin-Tai Chang
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Abstract
Method are provided for treating a wellbore or subterranean hydrocarbon-bearing formation to increase hydrocarbon recovery from the formation by in-depth mobility control and/or fluid diversion conformance by introducing a water soluble acrylamide polymer and a non-metallic organic crosslinking agent, or a crosslinkable acrylamide polymer, into an injection fluid entering the wellbore or the formation.
Claims28
A method of treating a wellbore or subterranean hydrocarbon-bearing formation to increase hydrocarbon recovery from the formation, the method comprising:
- introducing either a water soluble acrylamide polymer and a non-metallic organic crosslinking agent, or a crosslinkable acrylamide polymer, into an injection fluid entering the wellbore or the formation;
- wherein the acrylamide polymer and the crosslinking agent or the crosslinkable acrylamide polymer form a flowable crosslinked polymer in the presence of the injection fluid flowing within the formation and the flowable crosslinked polymer pushes the hydrocarbon out of the formation while the flowable crosslinked polymer continues to flow through the formation;
- the crosslinking agent comprising a polymeric polyamine which is either (i) a reaction product of a polymerization mixture comprised of at least one monomer of Formulae I, II, or III, or a salt thereof;
- or (ii) comprised of at least one structural unit of Formulae IA, IIA, IIIA, IIIB or IVB, wherein Formulae I, II, III, IA, IIA, IIIA, IIIB and IVA have the following structures:
- wherein:
- R1 is each independently hydrogen, a protecting group, or alkyl;
- and
- R2 R3, R4, R5, R6 and R7 are each independently hydrogen, alkyl, or alkoxylalkyl;
- and
- the crosslinkable acrylamide polymer comprising a reaction product of a polymerization mixture comprised of at least one acrylamide monomer and at least one monomer of the Formula I, II or III, or a salt thereof.
A method of increasing the sweep efficiency of a fluid flood of a subterranean hydrocarbon-bearing formation to enhance hydrocarbon recovery from the formation, the method comprising:
- introducing either a water soluble acrylamide polymer and a non-metallic organic crosslinking agent, or a crosslinkable acrylamide polymer, into an injection fluid entering a wellbore or the formation to form a crosslinked polymer in a high permeability zone existing within the formation;
- discontinuing hydrocarbon production from the formation being treated for a time period sufficient to allow the viscosity of the crosslinked polymer within the high permeability zone to increase so that the crosslinked polymer remains fixed within the high permeability zone to divert fluid flow into unswept zones of the formation;
- after the discontinuation step, introducing injection fluid into the formation being treated to flood the formation, mobilize the hydrocarbon and form a flood fluid;
- and
- removing the flood fluid containing the mobilized hydrocarbon from the well as a produced fluid,
- wherein the crosslinking agent comprises a polymeric polyamine which is either (i) a reaction product of a polymerization mixture comprised of at least one monomer of Formulae I, II, or III, or a salt thereof;
- or (ii) comprised of at least one structural unit of Formulae IA, IIA, IIIA, IIIB or IVA, wherein Formulae I, II, III, IA, IIA, IIIA, IIIB and IVA have the following structures:
- wherein:
- R1 is hydrogen, a protecting group, or alkyl;
- and
- R2, R3, R4, R5, R6 and R7 are each independently hydrogen, alkyl, or alkoxylalkyl;
- and
- the crosslinkable acrylamide polymer comprising a reaction product of a polymerization mixture comprised of at least one acrylamide monomer and at least one monomer of the Formula I, II or III or a salt thereof.
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Dependencies are inferred from the claim text.