Patent EA-003685-B1 (EA)
Title: Filter cake cleanup and gravel pack methods for oil based or water based drilling fluids
Inventor: PARLAR MEHMET
IPC: C09K8/52
Filed: 2001-02-15
Abstract: 1. A method of gravel packing a hole in a subterranean formation, a part of the formation adjacent to the hole having a filter cake coated thereon, said filter cake comprising an emulsion, said method comprising the step of injecting into the hole a gravel pack composition comprising gravel and a carrier fluid comprising an aqueous phase and further comprising the step of breaking or inverting the filter cake emulsion. 2. The method of claim 1, wherein the carrier fluid comprises an emulsion and further comprising the step of breaking or inverting the carrier fluid while simultaneously breaking or inverting the filter cake emulsion. 3. The method of claim 2, wherein the step of breaking or inverting the carrier fluid while simultaneously breaking or inverting the filter cake emulsion is performed by injecting a breaking composition after the step of injecting the gravel pack composition. 4. The method of claim 2, wherein the carrier fluid comprises an internal breaking composition to perform the step of breaking or inverting the carrier fluid while simultaneously breaking or inverting the filter cake emulsion. 5. The method of claim 1, wherein the filter cake emulsion is stable in a first pH range and the aqueous phase of the carrier fluid has a pH outside said first pH range. 6. The method of claim 2, wherein the filter cake emulsion is stable at pH greater than about 8 and the aqueous phase comprises a pH modifying agent selected from the group consisting of hydrochloric acid, formic acid and citric acid. 7. The method of claim 1, wherein the aqueous phase of the carrier fluid further comprises a chelating agent. 8. The method of claim 7, wherein the chelating agent is selected from the group consisting of di cationic salts of ethylenediaminetetraacetic acid (EDTA), cyclohexylene dinitrilo tetraacetic acid (CDTA), [Ethylenebis (oxyethylenenitrilo)] tetraacetic acid (EGTA) and [(Carboxymethyl)imino]-bis (ethylenenitrilo)]-tetra-acetic acid, hydroxyethylethylenediaminetriacetic acid (HEDTA) and Hydroxyethyliminodiacetic acid (HEIDA). 9. The method of claim 1, wherein the carrier fluid comprises a water-in-oil emulsion. 10. The method of claim 9, wherein about 50-70% by volume of the carrier fluid is aqueous phase. 11. The method of claim 1, wherein the carrier fluid comprises an emulsion and wherein the filter cake emulsion is broken by injecting into the wellbore a breaker composition that comprises at least one surfactant and solvent, said breaker composition simultaneously breaking the carrier fluid emulsion. 12. The method of claim 11, wherein the solvent comprises an alkoxylated aliphatic alcohol having from 4 to 20 carbon atoms. 13. The method of claim 12, wherein the solvent comprises 2-butoxyethanol. 14. A method of simultaneously gravel packing an open hole of a wellbore and removing filter cake from a subterranean formation adjacent to the open hole, the filter cake comprising a water in oil emulsion that is stable at pH greater than about 8; the method comprising the step of injecting into the wellbore a gravel pack composition that comprises gravel and a carrier fluid, wherein the carrier fluid comprises a water in oil emulsion having a continuous oil phase and a discontinuous aqueous phase, and wherein the aqueous phase comprises a solution of mineral acid or organic acid, whereby the pH of the aqueous phase is less than about 8 ; wherein the injection of the gravel pack composition simultaneously deposits gravel at or adjacent to the open hole of the wellbore and removes sufficient filter cake to establish a fluid flow path between the wellbore and the formation. 15. A method of simultaneously gravel packing an open hole of a wellbore and removing filter cake from a subterranean formation adjacent to the open hole, the wellbore having been drilled at least in part with an oil based drilling fluid, the filter cake comprising a water in oil emulsion that is stable in a first pH range; the method comprising the step of injecting into the wellbore a gravel pack composition that comprises gravel and a carrier fluid, wherein the carrier fluid comprises an aqueous continuous phase that comprises a gelled viscoelastic agent and EDTA, and wherein the aqueous phase has a pH outside the first pH range. 16. A gravel pack composition comprising gravel and a carrier fluid comprising an aqueous phase having a pH of less than about 8. 17. The composition of claim 16, wherein the aqueous phase comprises a pH modifying agent selected from the group consisting of hydrochloric acid, formic acid and citric acid. 18. The composition of claim 16, wherein the carrier fluid comprises a chelating agent. 19. The composition of claim 18, wherein the chelating agent is selected from the group consisting of di-cationic salts of ethylenediaminetetraacetic acid (EDTA), cyclohexylene dinitrilo tetraacetic acid (CDTA), [Ethylenebis (oxyethylenenitrilo)] tetraacetic acid (EGTA) and [(Carboxymethyl) imino]-bis (ethylenenitrilo)]-tetra-acetic acid, hydroxyethylethylenediaminetriacetic acid (HEDTA) and Hydroxyethyliminodiacetic acid (HEIDA). 20. The composition of claims 16-19, wherein about 50-70% by volume of the carrier fluid is aqueous phase.