Saudi Aramco has recently embarked on an exploration program targeted at evaluating potential heavy oil reserves, offshore Saudi Arabia’s eastern coast. The oil being tested is classified as heavy oil with an API gravity as low as 10 degrees (field measurement). Appraisal well testing in an offshore setting of such low API oil is difficult, especially when environmental considerations are of outmost importance. The tests objectives were to obtain accurate reservoir parameters, collect representative reservoir samples, and dispose of all produced hydrocarbons (heavy oil) without adversely impacting (spill/ polluting) the offshore environment. Being offshore, with limited space availability on jack-up rigs, it was also crucial that the design of the test equipment and procedures take into account the potential presence of Hydrogen Sulfide (H2S).

This paper will present best practices, experience gained, and lessons learnt from appraisal well testing of heavy oil at offshore locations. Several offshore heavy oil well tests were successfully carried out, where all produced hydrocarbons were flared off without causing spills or polluting the sensitive marine environment.