Methods of grouting offshore structures

Claim 1

A method of grouting an offshore structure having at least one supporting leg including a tubular jacket extending downwardly from above the water line to the sea bed and a piling driven through said jacket into the sea bed with an annular space existing between the inside of the jacket and said piling, said method comprising the steps of: a. sealing the upper end of said jacket to said piling so as to close said annular space at the upper end of the jacket; b. introducing into said annular space at a plurality of circumferentially spaced points adjacent the upper end of the jacket and above the water line a predetermined amount of grouting material which in relation to the total volume of the annular space is sufficient to form an annular column in the bottom portion of the annular space with hydrostatic pressure in excess of the sea water column on the outside, the sea bed being sufficiently porous so that sea water is displaced from the annular space through the lower end of the jacket by the introduced grouting material itself; c. allowing the introduced grouting material to set when the hydrostatic pressure is balanced, thus forming a plug in the bottom portion of the annular space; d. introducing additional grouting material into said annular space at a point adjacent the upper end of the jacket so that the additional grouting material fills the upper portion of the annular space above said plug; and e. allowing the additional grouting material to set.

Claim 2

A method of grouting an offshore structure having at least one supporting leg including a tubular jacket extending downwardly from above the water line to the sea bed and a piling driven through said jacket into the sea bed with an annular space existing between the inside of the jacket and said piling, said method comprising the steps of: a. sealing the upper end of said jacket to said piling so as to close said annular space at the upper end of the jacket; b. introducing into said annular space at a plurality of circumferentially spaced points adjacent the upper end of the jacket and above the water line a predetermined amount of grouting material which in relation to the total volume of the annular space is sufficient to form an annular column in the bottom portion of the annular space with hydrostatic pressure in excess of the sea water column on the outside, the sea bed being sufficiently porous so that sea water is displaced from the annular space through the lower end of the jacket by the introduced grouting material itself; c. allowing the introduced grouting material to set when the hydrostatic pressure is balanced, thus forming a plug in the bottom portion of the annular space; d. introducing additional grouting material into said annular space at a point adjacent the upper end of the jacket so that the additional grouting material fills the upper portion of the annular space above said plug; and e. allowing the additional grouting material to set.

Claim 3

A method of grouting an offshore structure having at least one supporting leg including a tubular jacket extending downwardly from above the water line to the sea bed and a piling driven through said jacket into the sea bed with an annular space existing between the inside of the jacket and said piling, said method comprising the steps of: a. sealing the upper end of said jacket to said piling so as to close said annular space at the upper end of the jacket; b. introducing a predetermined amount of grouting material into said annular space at a point adjacent the upper end of the jacket at a rate sufficient to form an annular column of grout in the upper end of said annular space, the amount of grouting material being sufficient that said annular column has a hydrostatic pressure in excess of the hydrostatic pressure of the sea water column on the outside, the sea bed being sufficiently porous so that sea water is displaced from the annular space through the lower end of the jacket by the downward movement in the annular space of the introduced grouting material itself; and c. allowing the introduced grouting material to set when it reaches the bottom of the annular space, thus forming a plug in the bottom portion of the annular space.

Claim 4

A method of grouting an offshore structure having at least one supporting leg including a tubular jacket extending downwardly from above the water line to the sea bed and a piling driven through said jacket into the sea bed with an annular space existing between the inside of the jacket and said piling, said method comprising the steps of: a. sealing the upper end of said jacket to said piling so as to close said annular space at the upper end of the jacket; b. introducing a predetermined amount of grouting material into said annular space at a point adjacent the upper end of the jacket at a rate sufficient to form an annular column of grout in the upper end of said annular space, the amount of grouting material being sufficient that said annular column has a hydrostatic pressure in excess of the hydrostatic pressure of the sea water column on the outside, the sea bed being sufficiently porous so that sea water is displaced from the annular space through the lower end of the jacket by the downward movement in the annular space of the introduced grouting material itself; and c. allowing the introduced grouting material to set when it reaches the bottom of the annular space, thus forming a plug in the bottom portion of the annular space.