Under certain downhole conditions the grades and connections can be exposed to high compression loads. These loads occur throughout the life of the well and are cyclical. These loads are generated from the operations of the well, local geology and the combination changes of both. This is experienced throughout the world by all operators.
Within the casing string, there are a number of sections that can be exposed to these loads, in which the connection is seen as the weak point of the string, though this must be in combination with the grade of steel selected.
When high compression occurs within a well is as per below:
With high compression, it is expected that the connection can withstand the pure compression loads in combination with the cyclic loading due to operations, while meeting sealbility requirements. To ensure performance, the connections thus have to be tested as a minimum to the ISO 13679 testing procedure.