The availability of smaller Mobile Offshore Drilling Units (MODUs) has reduced in recent years as older units have been scrapped, leaving newer units to service the market. The majority of these rigs have heavier and larger BOPS, which induce larger stresses and fatigue loading into the wells, which in turn could lead to a structural failure of the christmas tree or the wellhead and result in hydrocarbons being released into the environment.
Although this issue can be overcome on new wells by correctly specifying christmas tree and wellhead equipment, there remains an issue with older well stock that is already installed, with a large degree of uncertainty as to the remaining fatigue life of these wells.
One solution that has been proven to mitigate this issue is to restrain the Blow Out Preventer (BOP) using 4 winches equi-spaced (or as close as practicable) around the BOP and attach rope tethers to the BOP and apply tension using the winches. In this way, the BOP is restrained from moving as much and the loads substantially decreased.
The directors of TLA Subsea were involved in a project that used BOP tethering in 2020 and although the system was deployed successfully and fulfilled the requirement to limit BOP movement and therefore reduce the fatigue loadings imparted in to the Christmas tree and wellhead, they felt that the systems currently being offered were sub-optimal and have designed their own system to bring to the market.
The availability of smaller Mobile Offshore Drilling Units (MODUs) has reduced in recent years as older units have been scrapped, leaving newer units to service the market. The majority of these rigs have heavier and larger BOPS, which induce larger stresses and fatigue loading into the wells, which in turn could lead to a structural failure of the christmas tree or the wellhead and result in hydrocarbons being released into the environment.
Although this issue can be overcome on new wells by correctly specifying christmas tree and wellhead equipment, there remains an issue with older well stock that is already installed, with a large degree of uncertainty as to the remaining fatigue life of these wells.
One solution that has been proven to mitigate this issue is to restrain the Blow Out Preventer (BOP) using 4 winches equi-spaced (or as close as practicable) around the BOP and attach rope tethers to the BOP and apply tension using the winches. In this way, the BOP is restrained from moving as much and the loads substantially decreased.
The directors of TLA Subsea were involved in a project that used BOP tethering in 2020 and although the system was deployed successfully and fulfilled the requirement to limit BOP movement and therefore reduce the fatigue loadings imparted in to the Christmas tree and wellhead, they felt that the systems currently being offered were sub-optimal and have designed their own system to bring to the market.
The TLA Subsea BOP Tensioner
