Mitigate drilling risk and minimize cost when drilling to pre-salt /sub-salt reservoirs.
Drilling to pre-salt and sub-salt formations involves numerous challenges. Wellbore instability due to rubble zones as well as movement of salt into the wellbore, when drilling through the salt, can cause stuck pipe and require the well to be sidetracked.
Well-control problems are often encountered due to unexpected frac or pore-pressure gradients when drilling below the salt to reach the reservoir. These problems often require adding more casing points to the well plan, which can compromise attaining the desired wellbore ID or well TD in the objective reservoir. It can also add to drilling and completion costs due to high non-productive time.
Enventure’s expandable open-hole liners (OHL) are often planned into the base casing design to mitigate drilling risks. Unexpected challenges utilize OHL's as a contingency. Typical sizes used in these applications range from: 11-3/4 in. expandable OHL (for base casing of 14 in.), down to 5-1/2 in. (for base casing of 7 in.).
Expandable OHL's are often used to cover a problematic zone, providing an increased wellbore ID that allows drilling and completing with the next casing size as planned. This casing covers up the installed expandable OHL to maintain required wellbore pressure and collapse ratings.
Certain OHL sizes are available in High Performance (HP), with thicker wall to provide higher collapse and yield pressures - often at or exceeding the rating of the base casing. Sizes available are: 7-5/8 x 9-5/8-in., 8-5/8 x 10 3/4 in. and 11 3/4 x 13 3/8 in.
Technically difficult pre salt / sub salt wellbores are now planning in a 16 in. and/or 13-3/8 in. expandable OHL to enable larger casing prior to actually drilling through the salt intervals.
The SET® Chart provides a table of all the standard sizes available or you can use the SET® Designer to configure a system based upon your parameters.
The use of Enventure’s expandable OHL technology has enabled the drilling of offshore pre-salt and sub-salt wells that have saved operators $50 to $100 million in well re-drilling costs. More importantly, it has enabled multi-billion dollar offshore development programs to proceed as planned allowing hundreds of millions of boe to be recovered.
