Oilfield Consultant in Surface and Subsea Wellheads Equipment,Christmas Trees,Flow Control Equipment,Seals(Elastomerics & Metal-to-Metal)                     Contact me NEW E-mail: country45ve@yahoo.com

8.2 Retrievable Drilling Guide Base  (RGB)


In sequence of operations the drilling continues and now the crew needs to land secure the 30" DIA Conductor casing and they require now the use of the Retrievable/ Re-runnable Guide Base as you can see the structure is a solid square frame, made of beams per API 17.D specs. with a lower profile designed to accommodate on top of the funnel gimbal receiver on the TGB and top housing profile prep. for a cement tooling to fix and land the 30" DIA. OD. Conductor Casing that will support the wellhead and the Christmas tree, and all the loads generated during pulling and lowering devices to the well. Generally speaking loads are considered in the order of the millions of pounds. The RGB is lowered by means of the four lines and in the center is a tool connection to the riser that serves to pump fluids and cement. It also provides an internal profile to land the Conductor Housing which internally has the sealing and landing profile to accept the Cementing Head and many tools available.









The figure of the left shows a Riser some other call a Marine Riser, this is a tubular steel structure connected by a flanged connections heavy bolted and up to sea level is connected to the rig. This pieces connected together allows the installation/remotion of accessories and components to the Wellhead and Christmas Tree, also mud pumping for the well control. Is a strong piece of tubular steel structure, high alloy steel that also can carry two tubular fluid lines of steel high strength 180 DEG apart shown in yellow; the purpose of that auxiliary lines is to supply hydraulic fluid to control BOP shutdown, carry electric lines, among others. The use of this auxiliary steel lines is some times questionable because more the depth of the wellhead in the sea is, more will be the potential to form parafines and clog the lines as well as not to respond on time when an emergency arise, and you want  the BOP stack reacts quickly to shut down, instead of this lines for high depth of water is best the use of pressure containments packages and remote controlled by electro signals.

Figures down left and right show the sequence of operations that follow after the RGB is installed also is a ROV in red checking the installation, this is a vehicle that helps a lot in this and is a need to be used.



Finally the Casing Housing is installed ( figure left in gray) and the next steeps are basically followed by the installation of the Wellheads, the Casing Head Housing has typically a connector profile on top of it, to continue controlling the well isolation from the water, pumping mud in it, and every manufacturer has it's patented technical solution , in most cases the Vetco Gray NT-2, is suitable for this operations







Updated on:02/21/05Copyright @2003 Daniele Molaro Consulting

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