FILTER CAKE REMOVAL USING VISCOELASTIC SURFACTANT
A method of treating a wellbore for filter cake removal, the method comprising: injecting a reactive treatment fluid into a wellbore in a subterranean formation comprising a filter cake on a wall of the wellbore, the filter cake comprising an oil, a water-resistant polymer, a barite, and an inorganic salt, the reactive treatment fluid comprising, a viscoelastic surfactant (VES), a reactive breaker comprising an oxidizing salt, and an acid-generating material; and contacting the reactive treatment fluid with the filter cake in the wellbore, the reactive treatment fluid dissolving or exfoliating the barite from the wall into the reactive treatment fluid.
1 . A method of treating a wellbore for filter cake removal, the method comprising:
injecting a reactive treatment fluid into a wellbore in a subterranean formation comprising a filter cake on a wall of the wellbore, the filter cake comprising an oil, a water-resistant polymer, a barite, and an inorganic salt, the reactive treatment fluid comprising,
a viscoelastic surfactant (VES),
a reactive breaker comprising an oxidizing salt, and
an acid-generating material; and
contacting the reactive treatment fluid with the filter cake in the wellbore, the reactive treatment fluid dissolving or exfoliating the barite from the wall into the reactive treatment fluid.
2 . The method of claim 1 , further comprising, prior to providing the reactive treatment fluid into the wellbore, forming the wellbore by drilling using an oil-based drilling fluid (OBDF) comprising the oil, the polymer, and the barite, wherein the drilling forms the filter cake in the wellbore.
3 . The method of claim 1 , further comprising specifying a concentration of VES, the reactive breaker, or the acid-generating material in the reactive treatment fluid based on a characteristic of the subterranean formation and a design of the wellbore.
4 . The method of claim 1 , wherein the wellbore comprises a horizontal portion, and wherein a gelling performance of the VES gel promotes retention of the oxidizing salt in the reactive treatment fluid for breaking the water-resistant polymer in the horizontal portion of the wellbore.
5 . The method of claim 1 , wherein the oil comprises diesel oil or palm oil.
6 . The method of claim 1 , wherein the water-resistant polymer comprises ethylene-propylene polymer, maleated polymer, organophilic clay, or poly-a-olefins.
7 . The method of claim 1 , wherein the inorganic salt comprises calcium carbonate, bentonite, barite, ilmenite, hematite, or manganese tetroxide.
8 . The method of claim 1 , wherein the reactive treatment fluid comprises an inverting surfactant encapsulated in an encapsulating material that degrades at a temperature of the subterranean formation.
9 . The method of claim 8 , further comprising:
degrading the encapsulating material to release the inverting surfactant; and
inverting the filter cake with the inverting surfactant, wherein the inverting surfactant comprises an hydrophile-lipophile balance (HLB) of at least 12.
10 . A method of treating a wellbore, the method comprising:
drilling a wellbore in a subterranean formation using an oil-based drilling fluid (OBDF) comprising an oil, a synthetic polymer, a barite, forming a filter cake on a wall of the wellbore, the filter cake comprising the oil, the synthetic polymer, and the barite, the wellbore having a horizontal portion; and
performing a filter cake removal process comprising providing a reactive treatment fluid into the wellbore to remove the filter cake from the wall,
the reactive treatment fluid comprising,
a viscoelastic surfactant (VES) to gel the reactive treatment fluid to give the reactive treatment fluid as a VES gel,
a reactive breaker comprising an oxidizing salt to break the synthetic polymer, and
an acid-generating material to form acid.
11 . The method of claim 10 , wherein a gelling performance of the VES gel promotes retention of the oxidizing salt in the reactive treatment fluid for breaking the synthetic polymer in the horizontal portion of the wellbore.
12 . The method of claim 10 , the filter cake removal process further comprising providing carbon dioxide (CO 2 ) into the wellbore.
13 . The method of claim 12 , wherein the CO 2 is provided simultaneously with the reactive treatment fluid.
14 . The method of claim 10 , the filter cake removal process further comprising providing a second fluid comprising carbon dioxide (CO 2 ) into the wellbore.
15 . The method of claim 14 , the filter cake removal process further comprising alternately repeating the step of providing the reactive treatment fluid and the step of providing the second fluid.
16 . The method of claim 14 , wherein the second fluid further comprises an oxidizer.
17 . A method of treating a wellbore for filter cake removal, the method comprising:
providing a reactive treatment fluid into a wellbore in a subterranean formation comprising a filter cake on a wall of the wellbore, the filter cake comprising an oil, a water-resistant polymer, a barite, and an inorganic salt, the reactive treatment fluid comprising,
a viscoelastic surfactant (VES), the VES being 0.1 to 10 wt. % of the reactive treatment fluid;
a reactive breaker comprising a bromate, and
ammonium halide; and
dissolving or exfoliating the barite from the wall into the reactive treatment fluid.
18 . The method of claim 17 , wherein the bromate is sodium bromate (NaBrO 3 ) and the ammonium halide is ammonium chloride (NH 4 Cl).
19 . The method of claim 17 , wherein the oil comprises diesel oil or palm oil, wherein the water-resistant polymer comprises ethylene-propylene polymer, maleated polymer, organophilic clay, or poly-a-olefins, and wherein the inorganic salt comprises calcium carbonate.
20 . The method of claim 17 , further comprising foaming the reactive treatment fluid with carbon dioxide (CO 2 ).