System And Method For Sealing A Well

Abstract

A method of controlled hydration expansion of a smectite-containing day mineral (SCM) within an aqueous environment in a confined volumetric space, the method comprising the steps of: —introducing an amount of an SCM into said volumetric space via an inlet thereinto, and initiating the hydration expansion of the SCM to release SCM particles into the confined volumetric space, and increase the pressure therein; and —introducing a flow path modification to control said released SCM particles from undergoing a recompression, said modification thereby maintaining the pressure in the volumetric space.

Claims

1. A method of controlled hydration expansion of a smectite-containing clay mineral (SCM) within an aqueous environment in a confined volumetric space, the method comprising the steps of: introducing a body, which includes an amount of an SCM, into said volumetric space via an inlet thereinto; controlling the rate of release of SCM particles from the body by controlling hydration expansion conditions in the aqueous environment, to increase the rate at which said released SCM particles move between a first condition of being in close facing proximity to one another and a second condition of being spaced away from one another, wherein movement towards said second condition results in a relative change in pressure in the confined volumetric space; and introducing a flow path modification to limit the extent to which said released SCM particles are able to revert from the second condition to the first condition, and by such a limitation, to maintain the changed pressure in said volumetric space.

2-4. (canceled)

5. The method as claimed in claim 1, wherein the step of controlling hydration expansion conditions in the aqueous environment occurs simultaneously with the introduction of the body into the confined volumetric space.

6. The method as claimed in claim 1, wherein the step of introducing a flow path modification occurs simultaneously with the step of controlling hydration expansion conditions in the aqueous environment.

7. The method as claimed in claim 1, wherein the step of controlling the hydration expansion conditions in the aqueous environment involves the use of one or more introduced chemical substances which are arranged to react with one or more ionic materials in solution in said aqueous environment to form a solid product, thereby reducing the ionic strength in the aqueous environment and, consequentially, increasing the rate of release of SCM particles from the body.

8. The method as claimed in claim 7, wherein the solid product formed from the use of the or each introduced chemical substance forms a gel, in use which provides retention of the spatial separation of SCM particles in the second condition.

9-10. (canceled)

11. The method as claimed in claim 7, wherein the solid product is ettringite.

12. The method as claimed in claim 1, wherein, with the passage of time, the flow path modification which was initially applied to limit the extent to which the released SCM particles can revert from the second condition to the first condition, is replaced by a second flow path modification.

13. The method as claimed in claim 12, wherein the second flow path modification involves the use of one or more further introduced chemical substances to form a gel, in use which provides retention of the spatial separation of SCM particles in the second condition.

14-15. (canceled)

16. The method as claimed in claim 12, wherein the solid product is Strätlingite.

17. The method as claimed in claim 1, wherein the SCM particles are plate-like in shape, each of the major faces arranged in close facing proximity to a major face of another SCM particle, prior to hydration expansion.

18. The A method as claimed in claim 17, wherein as the first SCM particles within the confined volumetric space become hydrated, they move away from the hydrating body and towards a wall of the volumetric space, to form a zone of plate-like particles at the wall, unless limited from doing so by the flow path modification.

19. The method as claimed claim 1, wherein the step of controlling the hydration expansion conditions in the aqueous environment involves the introduction of a flow path modification in the form of a physical barrier which limits the extent to which said SCM particles are able to revert from the second condition to the first condition, and by such a limitation, to maintain the changed pressure in said volumetric space.

20. The method as claimed in claim 19, wherein the physical barrier disrupts the released, hydrated SCM particles from reforming into said first condition in which the particles are arranged in close facing proximity to one other.

21. The method as claimed in claim 1, wherein the body is in the form of a cylinder having an external circumferential diameter which is narrower than the diameter of the confined volumetric space, and of the inlet thereto, in use the method of controlled hydration expansion is preceded by the step of sliding the body through said inlet to a pre-determined location in said volumetric space.

22. The method as claimed in claim 21 wherein the body comprises a compressed core of SCM which experiences said controlled expansion conditions until said compressed core is at least partially consumed to a point of equilibrium in its expansion, whereupon an unconsumed remainder of said core provides the basis for future controlled hydration expansion as required.

23. The method as claimed in claim 22, wherein the confined volumetric space is defined by the annular space between an interior cylindrical wall of an underground well bore and an external cylindrical surface of the compressed core.

24. The method as claimed in claim 7, wherein the introduced chemical substance is an amount of each of member of the group comprising: Ordinary Portland Cement (OPC); Calcium sulfoaluminate cement (CSA).

25. The method as claimed in claim 24, wherein the or each introduced chemical substance is a combination of: more than 10% w/w of CSA and less than 80% w/w of OPC; alternatively of more than 20% w/w of CSA and less than 70% w/w of OPC; alternatively of more than 30% w/w of CSA and less than 60% w/w of OPC; alternatively of more than 40% w/w of CSA and less than 50% w/w of OPC; alternatively of more than 50% w/w of CSA and less than 40% w/w of OPC; alternatively of more than 60% w/w of CSA and less than 30% w/w of OPC; alternatively of more than 70% w/w of CSA and less than 20% w/w of OPC; and in the or each case, the balance of 10% w/w being made up of additional reactive ionic material (such as: sulfates); and other cement setting agents (such as: retardants or accelerants) to adjust the speed of hydration formation.

26. The method as claimed in claim 7, wherein the introduced chemical substance comprises an amount of each of the compounds in each of Group A and Group B, comprising: Group A Alite or Tricalcium silicate Ca.sub.3O.sub.5Si (C.sub.3S); Belite or Dicalcium silicate Ca.sub.2SiO.sub.4 (C.sub.2S); Tri-calcium aluminate (3CaO Al.sub.2O.sub.3) (C.sub.3A); Tetra-calcium aluminoferrite (4CaO Al.sub.2O.sub.3Fe.sub.2O.sub.3) (C.sub.4AF); Group B Belite or Dicalcium silicate Ca.sub.2SiO.sub.4 (C.sub.2S); gypsum (calcium sulfate n-hydrate, or Ca SO.sub.4.n-H.sub.20); tetra calcium trialuminate sulfate Ca.sub.4(AlO.sub.2).sub.6SO.sub.3.

27. The method as claimed in claim 24, wherein the total weight of water compared to the total weight of all introduced chemical substances subjected to controlled hydration expansion by being mixed into the water is a ratio of an uppermost figure of 3.5:1.0, or alternatively 2.5:1.0, or alternatively as low as 2.0:1.0.

28. The method as claimed in claim 11, wherein the ettringite, which provides retention of the spatial separation of hydrated particles of SCM when moved into the second condition, is formed in situ in the aqueous environment by creating: (i) a mixture of aluminate, sulfate, and calcium ions produced from the hydration of CSA cement; which, in the presence of: (ii) alkali (calcium hydroxide, (Ca(OH).sub.2)), produced from the hydration of dicalcium silicate Ca.sub.2SiO.sub.4; (C.sub.2S) which is present in Portland cement, and in CSA cement, reacts to form: calcium trisulfoaluminate hydrate, 3CaO.Al2O3.3 CaSO4.32 H2O, which is expansive in nature.

29. The method as claimed in claim 28, wherein formation of ettringite ceases when all of the sulfate ions, and some of the calcium ions from the mixture of step (i) are consumed.

30. The method as claimed in claim 29, wherein when the already-formed ettringite subsequently becomes unstable, converting to calcium monosulfoaluminate hydrate (AFm phase) CaO.Al.sub.2O.sub.3.CaSO.sub.4.12 H.sub.2O or C.sub.3A.CaSO.sub.4.12 H.sub.2O, and eventually dissolution to calcium, sulfate and aluminate ions.

31. The method as claimed in claim 16, wherein the Strätlingite Ca2Al2(SiO2)(OH)10.2.5(H2O), which provides retention of the spatial separation of hydrated particles of SCM when moved into the second condition, is formed in situ in the aqueous environment as follows: (i) about 7-15 days after the hydration of the SCM commences, an increase occurs in the rate of hydration of dicalcium silicate Ca 2SiO 4; (C 2S) which is present in both Portland cement, and in CSA cement; (ii) this results in the formation of an alkali (calcium hydroxide, (Ca(OH)2)), and silicate ions in solution; and in addition is combined with (iii) a mixture of aluminate, sulfate, and calcium ions are produced from the dissolution of the ettringite.

32. A method of controlled hydration expansion of smectite-containing clay mineral (SCM) solids when placed in an aqueous environment within an elongate wellbore, the method comprising the steps of introducing into the well bore: a predetermined quantity of an SCM in solid form; a predetermined quantity of a grout, the grout principally comprising a combination of each of: Ordinary Portland Cement (OPC) and Calcium sulfoaluminate cement (CSA); and a predetermined minimum quantity of water, wherein in use, the SCM solids undergo hydration expansion, due to spatial separation of hydrated particulates of SCM within the wellbore, and in the same environment, the water causes gel or crystalline hydration products of the cement to form on and between the hydrated particulates of SCM, thereby limiting the ability of the separated SCM particles to revert.

33. (canceled)

34. The method as claimed in claim 32 wherein the SCM prior to hydration is compressed into a solid form, which is of a tapered cylindrical shape which is able to go down a tortuous well, or in another physical form so that it can be inserted to reach any depth within a drilled well, including reaching the bottom of such a well, such as powder, particulates, pellets, mini cylinders.

35. The method as claimed in claim 32, wherein the total weight of water compared to the total weight of all introduced chemical substances subjected to controlled hydration expansion by being mixed into the water is a ratio of an uppermost figure of 3.5:1.0, or alternatively 2.5:1.0, or alternatively as low as 2.0:1.0.

36. A grout principally comprising a combination of each of: Ordinary Portland Cement (OPC) and Calcium sulfoaluminate cement (CSA), is the source for the mineral ettringite, which is formed in situ in an aqueous environment by creating: (i) a mixture of aluminate, sulfate, and calcium ions produced from the hydration of CSA cement; which, in the presence of: (ii) alkali (calcium hydroxide, (Ca(OH).sub.2)), produced from the hydration of dicalcium silicate Ca.sub.2SiO.sub.4; (C.sub.2S) which is present in Portland cement, and in CSA cement, reacts to form ettringite: calcium trisulfoaluminate hydrate, 3CaO.Al2O3.3 CaSO4.32 H2O, and wherein the grout comprises a combination of: more than 10% w/w of CSA and less than 70% w/w of OPC; alternatively of more than 20% w/w of CSA and less than 60% w/w of OPC; alternatively of more than 30% w/w of CSA and less than 50% w/w of OPC; alternatively of more than 40% w/w of CSA and less than 40% w/w of OPC; alternatively of more than 50% w/w of CSA and less than 30% w/w of OPC; alternatively of more than 60% w/w of CSA and less than 20% w/w of OPC; alternatively of more than 70% w/w of CSA and less than 10% w/w of OPC; and in the or each case, the balance of 20% w/w being made up of additional reactive ionic material (such as: sulfates); and other cement setting agents (such as: retardants or accelerants) to adjust the speed of hydration formation.

37. The method as claimed in claim 13, wherein the introduced chemical substance is an amount of each of member of the group comprising: Ordinary Portland Cement (OPC); Calcium sulfoaluminate cement (CSA).

38. The method as claimed in claim 37, wherein the or each introduced chemical substance is a combination of: more than 10% w/w of CSA and less than 80% w/w of OPC; alternatively of more than 20% w/w of CSA and less than 70% w/w of OPC; alternatively of more than 30% w/w of CSA and less than 60% w/w of OPC; alternatively of more than 40% w/w of CSA and less than 50% w/w of OPC; alternatively of more than 50% w/w of CSA and less than 40% w/w of OPC; alternatively of more than 60% w/w of CSA and less than 30% w/w of OPC; alternatively of more than 70% w/w of CSA and less than 20% w/w of OPC; and in the or each case, the balance of 10% w/w being made up of additional reactive ionic material (such as: sulfates); and other cement setting agents (such as: retardants or accelerants) to adjust the speed of hydration formation.

39. The method as claimed in claim 38, wherein the total weight of water compared to the total weight of all introduced chemical substances subjected to controlled hydration expansion by being mixed into the water is a ratio of an uppermost figure of 3.5:1.0, or alternatively 2.5:1.0, or alternatively as low as 2.0:1.0.

40. The method as claimed in claim 13, wherein the introduced chemical substance comprises an amount of each of the compounds in each of Group A and Group B, comprising: Group A Alite or Tricalcium silicate Ca.sub.3O.sub.5Si (C.sub.3S); Belite or Dicalcium silicate Ca.sub.2SiO.sub.4 (C.sub.2S); Tri-calcium aluminate (3CaO Al.sub.2O.sub.3) (C.sub.3A); Tetra-calcium aluminoferrite (4CaO Al.sub.2O.sub.3Fe.sub.2O.sub.3) (C.sub.4AF); Group B Belite or Dicalcium silicate Ca.sub.2SiO.sub.4 (C.sub.2S); gypsum (calcium sulfate n-hydrate, or Ca SO.sub.4.n-H.sub.20); tetra calcium trialuminate sulfate Ca.sub.4(AlO.sub.2).sub.6SO.sub.3.

41. The method as claimed in claim 40, wherein the total weight of water compared to the total weight of all introduced chemical substances subjected to controlled hydration expansion by being mixed into the water is a ratio of an uppermost figure of 3.5:1.0, or alternatively 2.5:1.0, or alternatively as low as 2.0:1.0.

42. The method as claimed in claim 26, wherein the total weight of water compared to the total weight of all introduced chemical substances subjected to controlled hydration expansion by being mixed into the water is a ratio of an uppermost figure of 3.5:1.0, or alternatively 2.5:1.0, or alternatively as low as 2.0:1.0.

Description

DESCRIPTION OF THE FIGURES

[0224] The accompanying drawings facilitate an understanding of the various embodiments which will be described:

[0225] FIG. 1 is a schematic side sectional view of a vertical well located in surrounding ground showing typical leakage pathways for fluids to pass via the well and up into aquifers, or up to the ground surface, in accordance with one aspect of the present disclosure;

[0226] FIG. 2 is a schematic side sectional view of a vertical well located in surrounding ground showing typical leakage pathways for fluids to pass via the well and up into aquifers, or up to the ground surface, in accordance with a further embodiment of the present disclosure;

[0227] FIG. 3 shows a chart classifying the various clay minerals comprising phyllosilicates.

[0228] FIG. 4 shows a schematic side sectional representation of a well passing into the ground for retrieval of Coal Seam Gas (CSG).

[0229] FIG. 5 shows a schematic, pictorial view of different platelet arrangements of bentonite in thixotropic and colloidal modes.

[0230] FIG. 6 shows a schematic, pictorial view of Van der Waals interactions.

[0231] FIG. 7 shows a schematic, pictorial view of the expected failure modes when a bentonite plug is used in a well.

[0232] FIG. 8 shows a schematic view of perpendicular plate expansion in aligned plates of montmorillonite.

[0233] FIG. 9 shows a schematic view of plate rotation on expansion in nonaligned plates of montmorillonite.

[0234] FIG. 10 shows a schematic view of plate alignment in the colloid forms at the casing interface.

[0235] FIG. 11 shows a schematic view of the “cone of force” and spherical expansion zone generation during hydration.

[0236] FIG. 12 shows a schematic view of the “cone of force” per the embodiment in FIG. 11.

[0237] FIG. 13 shows a schematic view of the overlapping cones of force per the embodiment in FIG. 11, now forming a plane of force.

[0238] FIG. 14 shows results of a dynamic expansion model using zonal differential expansion concept.

[0239] FIG. 15 shows results of an expansive prediction and photograph of a short narrow bentonite cylinder's expansion in a large diameter restraint. The overlap of the two spherical end expansion zones may be clearly seen as a central hole.

[0240] FIG. 16 shows the effect of salinity on swelling rate characteristics of compacted bentonite.

[0241] FIG. 17 shows an example of the equential plug failure penetration pressure R for 4 plugs.

[0242] FIG. 18 shows the cumulative resistance Σr to flow related to the length of the channel required for flow.

[0243] FIG. 19 shows the empirical bleed failure of 10 compressed bentonite cylinders.

[0244] FIG. 20 shows the dilation of the montmorillonite plates on applied pressure.

[0245] FIG. 21 shows the frictional failure pressure of a single 139.7×240 mm compressed cylinder in a 193.7 mm ID casing.

[0246] FIG. 22 shows the frictional failure dislodgment pressure of a grouted single 139.7×240 mm compressed cylinder in a 193.7 mm ID casing.

[0247] FIG. 23 shows the frictional failure pressure of a self-healed grouted single 139.7×240 mm compressed cylinder in a 193.7 mm ID casing

[0248] Table 1—shows the chemical composition of the group of the present invention, and which is used in the present inventive method and system.

TABLE-US-00001 TABLE 1 DETAILS OF THE GROUT Grout component Grout introduces specific phases Grout component functional group hydration component or fonctional groups products Ordinary Alite or Tricalcium silicate C .sub.3S hydrates to calcium silicate hydrate (Ca .sub.2H .sub.2O .sub.5Si, aka Portland Ca .sub.3O .sub.5Si (abbreviated to C .sub.3S) C—S—H) Cement (OPC) Dicalcium silicate Ca .sub.2SiO .sub.4 C 2S gives a hydration product of calcium hydroxide (abbreviated to C .sub.2S) (Ca(OH) .sub.2) (abbreviated to CH) aka hydrated lime, or Portlandite. Tri-calcium aluminate (3CaO C .sub.3A gives a hydration product of aluminate and hydroxyl ions Al.sub.2O.sub.3) (C .sub.3A) and Tetra-calcium alaminoferrite C .sub.4AF gives a hydration product of aluminate and hydroxyl (4CaO Al.sub.2O.sub.3Fe.sub.2O.sub.3) (C .sub.4AF) in ions water produce aluminate and hydroxyl ions gypsum (calcium sulfate dihydrate, In water the gypsum partially dissolves releasing calcium and or Ca SO.sub.42H.sub.2O) sulfate ions to react with the aluminate. Calcium sulfo Belite or Dicalcium silicate, C .sub.2S gives a hydration product of calcium hydroxide aluminate Ca .sub.2SiO .sub.4 (abbreviated to C .sub.2S), (Ca(OH) .sub.2) (abbreviated to CH), aka hydrated lime, or (CSA) cement Portlandite. gypsum (calcium sulfate dihydrate, In water the gypsum partially dissolves releasing calcium and or Ca SO.sub.4.2H.sub.2O); and sulfate ions to react with the aluminate. tetra calcium trialuminate sulfate CSA cement hydrates so that the aluminate, sulfate, calcium Ca.sub.4(AlO.sub.2)SO.sub.3 source of aluminate, and hydroxyl ions can reform as calcium trisulfo aluminate sulfate and calcium ions hydrate ettringite, (AFt phase) which in the presence of lime is expansive in nature 3CaO•Al.sub.2O.sub.3•3 CaSO.sub.4•32 H.sub.2O or C.sub.3A•3 CaSO.sub.4•32 H.sub.2O or as calcium sulfo aluminate hydrate monosulfate, (AFm phase) CaO•Al.sub.2O.sub.3•CaSO.sub.4•12 H.sub.2O or C.sub.3A•CaSO.sub.4•12 H.sub.2O

[0249] In the foregoing description of certain embodiments, specific terminology has been resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. Terms such as “upper” and “lower”, “above” and “below” and the like are used as words of convenience to provide reference points and are not to be construed as limiting terms.

[0250] In this specification, the word “comprising” is to be understood in its “open” sense, that is, in the sense of “including”, and thus not limited to its “closed” sense, that is the sense of “consisting only of”. A corresponding meaning is to be attributed to the corresponding words “comprise”, “comprised” and “comprises” where they appear.

[0251] The preceding description is provided in relation to several embodiments which may share common characteristics and features. It is to be understood that one or more features of any one embodiment may be combinable with one or more features of the other embodiments. In addition, any single feature or combination of features in any of the embodiments may constitute additional embodiments.

[0252] In addition, the foregoing describes only some embodiments of the inventions, and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive.

[0253] Furthermore, the inventions have described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the inventions. Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realise yet other embodiments.