High Compression

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.

Challenges

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:​ 

 

​​Local geologyOperations – i​nstallation, production cycling, worko​vers, cementing
​Depth of the well​Design of the well
​Deviated wells​Compaction due to depletion of the reservoir

​​​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.

Solutions

  • Select increased strength of tubulars to provide overall enhanced performance
    • Control yield grades
    • High yield strength sour service grades
    • Increased manufacturing specifications greater than API 5CT or ISO 13680.
  • Request ISO 13679 CAL-IV tested connections for tubing, liners and production casing to ensure that the performance obtained is not just pure structural performance and is able to withstand the operational loads with gas tightness maintained.
  • ​For intermediate or large diameter connections request ISO 13679 CAL-III or CAL-IV connections to ensure guaranteed performance.