COMPOSITIONS FOR USE IN WELL CONSTRUCTION, REPAIR AND/OR ABANDONMENT

摘要

1. Method for carrying out well construction, repair or abandonment operations which comprises using an addition-curing silicone formulation, the method comprising using a silicon formulation selected from the group including a room temperature vulcanisable silicone formulation and a fluor-containing silicon rubber. 2. Method according to claim 1, which comprises isolating a zone or replacing a damaged or corroded casing by placing a two component room temperature vulcanisable silicone formulation in the well bore and allowing it to form a resilient rubber-type material. 3. Method according to claim 1, which comprises curing annular (gas) pressure in oil and/or gas wells by sealing off the offending annulus by injecting a two component room temperature vulcanisable silicone formulation into the annulus and allowing it to form a tough visco-elastic silicone gel plug. 4. Method according to claim 3, which comprises flushing a brine solution into the annulus to equilibrate the annular fluid column with the existing reservoir pressure after the visco-elastic plug has been allowed to form. 5. Method according to claim 1, which comprises shutting-off watered or gassed-out zones of an oil reservoir by plugging such zone by an impermeable silicone gel system which is initially squeezed into the porous zone as the two component room temperature vulcanisable silicone formation which is then allowed to form an impermeable barrier to water or gas flow. 6. Method according to claim 1, which comprises preventing and/or controlling gas influx into a section of an oil/gas well during primary cementation by using a two component room temperature vulcanisable silicone formulation as a squeeze fluid into the well bore, having landed a casing, and applying a predetermined pressure to force the squeeze fluid radially into permeable formations of the well bore wall to create a flushed zone of reduced permeability to gases, followed by a cement-type of annular sealing. 7. Method according to claim 6, which comprises using a cement-type of annular sealing in which the cementitious component also contains a two component room temperature vulcanisable silicone formulation. 8. Method according to claim 1, which comprises using the two component room temperature vulcanisable silicone formulation to create a silicone rubber packer. 9. Method according to claim 1, which comprises using a two component room temperature vulcanisable silicone formulation to inflate external casing packers. 10. Method according to claim 1, which comprises forming a temporary or permanent plug in a well bore in one or more subterranean formations penetrated by the well bore which comprises either placing a mixture of a cement and an addition-curing silicone formulation in said one or more subterranean formations or in said well bore at a desired location therein or placing an addition-curing silicone formation below or on top of an existing non-gas tight plug and allowing the silicone formulation to set thereby producing a gas tight plug. 11. Method according to claim 10, which comprises using a silicone formulation and a cement in which the silicone/-cement weight ratio is between 5:1 and 0.5:1, preferably between 3:1 and 1:1. 12. Method according to claim 10 or 11, which comprises using a Class G or H Portland cement as the cementitious component in the silicone/cement mixture. 13. Method according to one or more of claims 10 to 12, which comprises carrying out the production of the gas tight plug at a temperature in the range between ambient and 180 degree C, suitably up to 150 degree C and in particular between 40 and 70 degree C. 14. Method according to one or more of claims 1 to 13, which comprises using additionally a retarder or an accelerator to influence the setting behaviour of the silicone formulation. 15. Method according to one or more of claims 10 to 14, which comprises using a silicone rubber, preferebly a fluor-containing silicone rubber. 16. Method according to claim 15, which comprises using a two-component silicone formulation, preferably fluor-containing silicone rubber. 17. Method according to one or more of claims 1 to 16, which comprises using one or more of Dow Corning 3-4225, 3-4230, 3-4231, 3-4232 or 3-4234 products. 18. Method according to any one of claims 1 to 17 as described hereinbefore with particular reference to the Examples.