Abstract: Offshore wells are drilled with an improved drivepipe/casing assembly made up of plural sections of casing connected end to end, which are driven to a predetermined depth followed by drilling out a wellbore portion below the lower distal end of the casing assembly and then followed by redriving the drivepipe/casing assembly to refusal to eliminate the need for a conventional casing string and associated cementing operations. Certain ones of the casing sections are provided with earth impinging and displacing rings of slightly larger diameter than the outside diameter of the casing to reduce earth to casing friction during driving and to minimize the redriving effort required.

Abstract: A freestanding offshore well structure includes a generally cylindrical caisson having a relatively small diameter drivepipe section connected to a larger diameter caisson section which is of sufficient strength to withstand wind and wave action. An upper portion of the drivepipe section is provided with a landing ring for a hanger for a conductor casing string or a wellhead body for a surface pipe string. A casing connector or nipple supports a diverter above the landing ring. The caisson is driven to refusal, the diverter attached to the upper end of the caisson and drilling operations and installation of the casing string, surface pipe and wellhead body are carried out through the diverter. The diverter is then removed and connection of wellhead valve bodies, handles and associated conduits to the wellhead is then carried out to complete the well assembly.

Abstract: In order to salvage a slot path on an offshore platform wherein the original conductor pipe has become clogged or otherwise rendered unusable, the original conductor is cut off below mudline, thereby leaving a stub forming a base upon which a suitably oriented deflector trough is attached. A new or replacement conductor is installed along the same slot path until the deflector trough causes the new conductor to follow a deviated path so as to avoid the original conductor. The direction of the deflector trough is selected to avoid existing wells already driven from such structure.