Deviated conductor driving system

Abstract

A method and technique for a deviated (non-vertical) emplacement of a conductor casing at a desired .[.curver.]. .Iadd.curve .Iaddend.and orientation in order to facilitate directional drilling of a well in the substratum of an offshore well site. The method provides for the installation of a relatively short, offset portion of the conductor casing at only the bottom of the conductor pipe string and thereby utilizing this offset portion to force the conductor string in a desired direction and orientation by driving or forcing the conductor casing through a substratum in such a manner that the casing will assume the desired curvature and direction as it advances through the substratum. In addition to the offset or dog-leg segment at the bottom, key-way type guide bars can be added in the longitudinal direction to resist undesired rotation of the conductor pipe.

What is claimed as the invention is: 
     
       1. A method providing a deviated conductor system at an offshore body of water site for directional drilling of wells comprising the following steps: a. providing an open ended conductor casing of incremental segments;   b. securing an open ended dog-leg section on the distal end of the otherwise straight conductor producing a longitudinally elongated, off-set portion extending over laterally past one side of the outer circumference of the otherwise straight conductor, said off-set being open ended;   c. .[.setting.]. .Iadd.lowering .Iaddend.said conductor .[.through vertically aligned guides.]. .Iadd.down .Iaddend.until the muoline is reached, maintaining or positioning the dog-leg in the desired directional orientation; and   d. driving said open ended conductor with said open ended dog-leg section through the substratum causing the conductor to be laterally deviated due to the interaction of the substratum against the offset, lower side surfaces of said dog-leg section from its entry into the substratum to its final deviated position.   
     
     
       2. The method of claim 1 wherein said method further includes the step of: e. verifying the curvature and orientation of the deviated conductor and taking any correctional steps desired to alter the deviation.   
     
     
       3. The method of claim 1 wherein step b said dog-leg is provided by cutting off the tip of the initial conductor segment and rewelding the tip at a slight angle to the axis of the remaining straight conductor. 
     
     
       4. The method of claim 1 where there is further included in the initial steps the step of: adding at least one projecting flat bar along the exterior of the conductor parallel to the main longitudinal axis of the conductor to minimize or counteract any tendency of the conductor to rotate.   
     
     
       5. The method of claim 1 wherein in step b there is further included the step of continuously marking on each incremental segment of the conductor pipe the directional orientation of the dog-leg. 
     
     
       6. The method of claim 5 wherein in step b the directional position of the dog-leg is recorded by painting a longitudinal line on each incremental segment of the conductor as it is added onto the preceding ones. 
     
     
       7. A deviated conductor system for an anchored marine structure at an offshore body of water site adapted for directional drilling of wells which comprises: conductor .[.guide.]. .Iadd.receiving .Iaddend.means carried on said structure being adapted to receive .[.and guide.]. a conductor passed downwardly therethrough .[., said conductor guide means including discrete guide units spaced vertically apart in at least substantial vertical alignment.]. ;   a working deck positioned above the water's surface;   at least one elongated leg supportably connected to said working deck and extending downwardly to the floor of said body of water; and   an elongated open ended conductor passing downwardly and .[.registered.]. .Iadd.positioned .Iaddend.in .[.said discrete guide means of.]. said conductor .[.guide.]. .Iadd.receiving .Iaddend.means and penetrating substantially down into the substratum of said body of water, and deviated laterally into the substratum a substantial distance away from the .[.vertical.]. line defined by .[.said guide means,.]. the position of said conductor at the level of said working deck and the point of entry of said conductor into the substratum, said conductor having an open ended, offset dog-leg segment at its distal end offset a slight amount from the longitudinal axis of said conductor, which open ended, offset dog-leg portion extends over laterally past one side of the outer circumference of the main body of the conductor.   
     
     
       8. A conductor for producing a deviated conductor system for an anchored marine structure at an offshore body of water site adapted for directional drilling of wells which comprises: a substantially long, open ended conductor pipe made up of a multiple number of individual conductor pipe segments welded together; and   an open ended offset dog-leg segment secured to its distal end which projects out by means of the offset laterally past one side of the main conductor pipe, the conductor otherwise being made of straight-in-line segments.   
     
     
       9. A method of providing a deviated conductor system at an offshore body of water site for directional drilling of wells comprising the following steps: a. providing a conductor casing of incremental segments;   b. welding a dog-leg section on the distal end of the otherwise straight conductor;   c. .[.setting.]. .Iadd.lowering .Iaddend.said conductor .[.through vertically aligned guides.]. .Iadd.down .Iaddend.until the mudline is reached, maintaining or positioning the dog-leg in .Iadd.the .Iaddend.desired directional orientation;   d. driving said conductor with said dog-leg through the substratum causing the conductor to be laterally deviated from its entry into the substratum to its final deviated position;   e. verifying the curvature and orientation of the deviated conductor and taking any correctional steps desired to alter the deviation; and   f. if step e indicates excessive curvature, there is included the further step of drilling out the stratum of soil below the tip of the conductor pipe for a short distance beyond the end of the conductor, causing the conductor pipe to tend to drop down to decrease the curvature.   
     
     
       10. A method of providing a deviated conductor system at an offshore body of water site for directional drilling of wells comprising the following steps: a. providing a conductor casing of incremental segments;   b. welding a dog-leg section on the distal end of the otherwise straight conductor;   c. .[.setting.]. .Iadd.lowering .Iaddend.conductor .[.through vertically aligned guides.]. .Iadd.down .Iaddend.until the mudline is reached, maintaining or positioning the dog-leg in the desired directional orientation;   d. driving said conductor with said dog-leg through the substratum causing the conductor to be laterally deviated from its entry into the substratum to its final deviated position;   e. verifying the curvature and orientation of the deviated conductor and taking any correctional steps desired to alter the deviation; and   f. if step "e" indicates insufficient curvature, there is further included the step of providing a dog-leg on subsequent .[.conductors.]. .Iadd.conductor segments .Iaddend.having a greater off-set than originally anticipated. .Iadd. 11. The method of claims 1, 9 or 10 wherein there is included a set of vertically aligned guides and step "c" includes the step of setting said conductor through the vertically aligned guides. .Iaddend..Iadd. 12. The system of claim 7 wherein said conductor receiving means also comprise conductor guide means for guiding a conductor passed downwardly therethrough, said conductor guide means including discrete guide units spaced vertically apart in at least substantial vertical alignment, said conductor also being registered in said discrete guide means and being deviated laterally into the substratum a substantial distance away from the vertical line defined by said guide means.