Offshore floating production method

• US 6,494,271 B2
• Filed: 04/04/2002
• Issued: 12/17/2002
• Est. Priority Date: 04/25/2001
• Status: Expired due to Term

• Current Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Original Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Inventors: Wilson, W. Brett
• Primary Examiner(s): Neuder, William
• Application Number:
  US10/116,232
• Publication Number:
  US 20020157833A1
• Time in Patent Office: 257 Days
• Field of Search: 175/5, 175/7, 414/3, 414/4, 114/230.1, 114/293
• US Class Current: 175/5
• CPC Class Codes: B63B 21/50 Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
• CPC Class Codes: E21B 15/02 specially adapted for underwater drilling E21B15/04 takes precedence
• CPC Class Codes: E21B 43/01 specially adapted for obtaining from underwater installations

Abstract

A method of conducting operations to an offshore field from multiple separated drill centers using a floating vessel having a turret-mounted mooring element and a workstation separate from the mooring element in which the vessel is moored at a central mooring element location and operations are sequentially carried out at separate drill centers associated with the mooring element location by allowing the vessel to weathervane to a heading associated with a subsequent drill center once operations have been completed at a first drill center.

Claims

1. A method of conducting operations to an offshore field from multiple separated drill centers, the method using a floating vessel having a turret-mounted mooring element and further having a workstation horizontally spaced apart from the mooring element, comprising the steps of:

a) locating the mooring element approximately over a first mooring element location;

(b) limiting the horizontal movement of the mooring element using a plurality of mooring lines extending from the mooring element;

(c) allowing the vessel to weathervane such that the workstation is substantially vertically aligned over a first drill center associated with the first mooring element location;

(d) temporarily restraining the weathervaning of the vessel;

(e) using the workstation to conduct operations in at least one well from the first drill center to the field;

(f) removing the weathervaning restraint while continuing to limit horizontal movement of the mooring element and repeating steps (c), (d) and (e) for one or more additional drill centers associated with the first mooring element location.

2. The method of claim 1 wherein the drill centers are located on an arc with the center of the arc falling on a vertical axis passing approximately through the first mooring element location.

3. The method of claim 1 where the wells in each of the drill centers are associated with a sector of the field, the bottom location of each such well located within such sector.

4. The method of claim 1 comprising the additional steps of:

(g) providing product receiving means in the mooring element for receiving hydrocarbon product lines from one or more of the drill centers;

(h) providing means for passing hydrocarbon product from the product receiving means to topside facilities onboard the vessel; and

(i) simultaneously with conducting the operations of step (e), passing hydrocarbon product from one or more of the drill centers to the topside facilities.

5. The method of claim 1 comprising the additional steps of:

(g) re-positioning the mooring element approximately over a second mooring element location;

(h) limiting the horizontal movement of the mooring element using a plurality of mooring lines extending from the mooring element;

(i) allowing the vessel to weathervane such that the workstation is substantially vertically aligned over a first drill center associated with the second mooring element location;

(j) temporarily restraining the weathervaning of the vessel;

(k) using the workstation to conduct operations in at least one well from the first drill center associated with the second mooring element location.

6. The method of claim 5, comprising the additional step of

(l) removing the weathervaning restraint of step (j) while continuing to limit horizontal movement of the mooring element and repeating steps

(g), (h) and (i) for one or more additional drill centers associated with the second mooring element location.

7. The method of claim 5 comprising the additional steps of:

(l) providing product receiving means in the mooring element for receiving hydrocarbon product lines from the drill centers associated with at least one of the mooring element locations;

(m) providing means for passing hydrocarbon product from the product receiving means to topside facilities onboard the vessel; and

(n) simultaneously with conducting the operations with the workstation, passing hydrocarbon product to the topside facilities.

8. The method of claim 5 wherein the drill centers for the first mooring element location form an arc with the center of the arc falling on a vertical axis centered approximately on the first mooring element location and the drill centers for the second mooring element location form a second arc with the center of the second arc falling on a vertical axis centered approximately on the second mooring element location.

9. A method of conducting operations to an offshore field from multiple separated drill centers, the method using a floating vessel having a turret-mounted mooring element and further having a first workstation horizontally spaced apart from the mooring element and further having a second workstation, comprising the steps of:

(a) locating the mooring element approximately over a first mooring element location;

(b) limiting the horizontal movement of the mooring element using a plurality of mooring lines extending from the mooring element;

(c) allowing the vessel to weathervane such that the first workstation is substantially vertically aligned over a first drill center associated with the first mooring element location;

(d) temporarily restraining the weathervaning of the vessel;

(e) using the first workstation to conduct operations in at least one well from a first segment of the first drill center while simultaneously using the second workstation to conduct operations in a well from a second segment of the first drill center;

(f removing the weathervaning restraint while continuing to limit horizontal movement of the mooring element and repeating steps (c), (d) and (e) for one or more additional drill centers associated with the first mooring element location.

10. The method of claim 9 wherein the first segments of each of the drill centers are located on an arc with the center of the arc falling on a vertical axis passing approximately through the first mooring element location, and the second segments of each of the drill centers are located on a second arc with the center of the second arc falling on a vertical axis passing approximately through the first mooring element location.

11. The method of claim 9 where the wells in each of the segments are associated with a sector of the field, the bottom location of each such well located within such sector.

12. The method of claim 9 comprising the additional steps of:

(g) providing product receiving means in the mooring element for receiving hydrocarbon product lines from one or more of the segments;

(h) providing means for passing hydrocarbon product from the product receiving means to topside facilities onboard the vessel; and

(i) simultaneously with conducting the operations of step (e), passing hydrocarbon product from one or more of the segments to the topside facilities.