PRESSURE GROUTING

• US 3,832,857 A
• Filed: 08/14/1973
• Issued: 09/03/1974
• Est. Priority Date: 05/07/1973
• Status: Expired due to Term

• Current Assignee: Max Bassett
• Original Assignee: Max Bassett
• Inventors: Bassett, Max
• Primary Examiner(s): Shapiro, Jacob
• Application Number:
  US05/388,085
• Time in Patent Office: 385 Days
• Field of Search: 61/46,46.5,53.52,53.6,56,56.5,50,52,53.74
• US Class Current: 405/225
• CPC Class Codes: E02B 17/0008 Methods for grouting offshore structures; apparatus therefor cementing boreholes E21B33/13

Abstract

A method for grouting the annulus between the jacket and piling in the legs of an offshore structure in which air is introduced to expel water from the lower end of the annulus, and the annulus is then filled from the top with grouting material. Water may be pumped down the annulus to wash out mud. Some grout may be pushed out the bottom of the annulus to remove mud or to form a bell foundation.

Claims

1. A method of grouting an offshore structure having at least one supporting leg including a substantially vertically extending tubular jacket in the water and a piling in said jacket having an outside diameter smaller than the inside diameter of the jacket whereby a space is formed between the inside of the jacket and said piling;

said space being closed at its upper end and open to the sea bed at its lower end, wherein said space initially has mud in at least the lower portion thereof, said method comprising the steps of flowing water down through said space and out the lower end to wash out the mud, expelling the water from the space out its lower end by application of air pressure, flowing fluid grouting material down through said space to the lower end while maintaining sufficient air pressure to prevent water from returning, and permitting the grouting material to set.

2. A method as defined by claim 1 and including causing a portion of said grouting material to flow out the lower end of the space to form a bell around the lower end of the jacket.

3. A method as defined by claim 1 wherein an initial portion of the grouting material is allowed to flow to the bottom of the space, and air pressure is applied to it until it sets, and then flowing additional grouting material into the space, and allowing the additional grouting material to set.

4. A method as defined in claim 1 and including injecting water into said space prior to the insertion of any grouting material, and causing the injected water to flow out the lower end of the space.

5. A method of grouting an offshore structure having at least one supporting leg including a substantially vertically extending tubular jacket in the water and a piling in said jacket having an outside diameter smaller than the inside diameter of the jacket whereby a space is formed between the inside of the jacket and said piling, said space being closed at its upper end and open to the sea bed at its lower end, said method comprising the steps of pumping water into said space at a pressure sufficient to force water out the lower end of the space through the sea bed formation, then applying sufficient air pressure to said space to force substantially all of the liquid out the lower end, flowing fluid grouting material down through said space to the lower end while maintaining sufficient air pressure to prevent water from returning, and permitting the grouting material to set up.

6. A method as defined by claim 5 and including causing a portion of said grouting material to flow out the lower end of the space before it sets up, so that upon setting the grouting material will form a bell around the lower end of the jacket.

7. A method as defined by claim 5 wherein an initial pOrtion of the grouting material is allowed to flow to the bottom of the space, and then flowing additional grouting material into the space.

8. A method as defined by claim 7 wherein said initial portion of grouting material is insufficient to compensate for the pressure head of the overlying sea, and wherein air pressure is maintained on the grouting material sufficient to compensate for said pressure head until said initial portion of grouting material sets up.

9. A method of grouting an offshore structure having at least one supporting leg including a tubular jacket extending downwardly from above the waterline 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 annular space being closed at its upper end and open to the sea bed at its lower end, said method comprising the steps of applying air under pressure to said annular space to force water therein out the lower end, while maintaining sufficient air pressure to keep out the water, flowing grouting material to the lower end of said annular space and allowing it to set up, releasing the air pressure, flowing additional grouting material into the annular space, and allowing the additional grouting material to set up.

10. A method of grouting an offshore structure having at least one supporting leg including a tubular jacket extending downwardly from above the waterline 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 annular space being closed at its upper end and open to the sea bed at its lower end, said method comprising the steps of applying air under pressure to said annular space to force water therein out the lower end, thereby reaching an air pressure in said annular space sufficient to overcome the pressure head of the overlying sea water, flowing fluid grouting material down through said annular space to the lower end, while gradually reducing air pressure to compensate for the pressure head exerted by the grouting material, until sufficient grouting material is in the annular space to overcome the pressure head of the overlying sea water without the use of any air pressure, flowing an additional amount of fluid grouting material into said annular space, whereby fluid grouting material is forced out the bottom of the annular space, and allowing the grouting material to set up.