Tension buoyant tower

A method for producing one or more offshore wells, comprising:

• (a) transporting an elongate stem and an upper module offshore, wherein the upper module includes a variable ballast chamber, wherein the stem comprises a plurality stem modules coupled together end-to-end, and wherein each stem module includes a variable ballast chamber;
• (b) transitioning the stem from a horizontal orientation to a vertical orientation;
• (c) attaching the upper module to an upper end of the stem to form a tower;
• (d) ballasting the tower;
• (e) moving a ballast control conduit along the stem after (c) to ballast or deballast one or more of the variable ballast chambers of the stem modules;
• and
• (f) pivotally coupling the tower to an anchor disposed at the sea floor at a first offshore installation site.

An offshore structure, comprising:

• a tower having a longitudinal axis, an upper end, and a lower end opposite the upper end;
• wherein the tower comprises an elongate stem extending from the lower end, an upper module coupled to the stem, and a deck mounted to the upper module at the upper end;
• wherein the upper module is net buoyant;
• a conduit coupling member extending radially outward from the stem, the conduit coupling member including a guide tubular coupled to the stem;
• a first ballast control system configured to adjust the buoyancy of the upper module, the first ballast control system including a first conduit;
• a second ballast control system configured to adjust the buoyancy of the stem, the second ballast control system including a second conduit configured to be moveably received by the guide tubular of the conduit coupling member;
• and
• an anchor configured to be secured to the sea floor, wherein the anchor is pivotally and releasably coupled to the lower end of the tower.