The use of downhole continuous chemical injection (DHCI) has become common in Equinor, with around 30-40 % of new wells being equipped with DHCI in the last decade. Scale inhibitor supply accounts for around three quarters of the installations. A rough estimate of present-day situation points to around a third of the installations not being operational, with some form of clogging seemingly the most common cause. Around 1 % of the installations are unavailable due to detrimental fails (leakages likely from corrosion) that either led to, or could have led to, well integrity being compromised.

This underlines that these systems come with a complexity and risk associated with them and should be installed on a per need basis. The purpose of this work is to provide simple guidelines on which wells DHCI should be installed, and which do not need it.

We propose that the base case should be to include downhole scale inhibitor lines for oil wells, but not install in gas/condensate wells unless significant water production is expected. For the former, lower temperature wells (<80 °C) with a low sulphate scale risk are typical cases where lines could potentially be omitted. What expected water rate that should lead to installation of DHCI in gas/condensate wells is system dependent, but generally < 100 m3 water per MSm3 gas should be unproblematic while at magnitude > 1000 m3 water per MSm3 gas, DHCI should be evaluated.

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