In south-eastern part of the Sultanate of Oman, PDO is producing from one of Tight Sour Field (with H2S 1-2%) with current reservoir pressures ranging from 40,000 to 60,000kpa for more than 20 yrs. Due to tight nature of reservoir, the wells are hydraulically fracced to produce, but with time the production rates decline and wells start to produce in unstable mode. This unstable production mode leads to huge scaling and corrosion issues which results in tubing failures requiring huge and expensive workover to restore well production. Due to low production rates and expensive workover makes these intervention very less attractive in terms of Net Present Value (NPV) compared to other opportunities.
This paper describes the challenges in restoring production from wells with tubing leaks using conventional workover techniques and the advantages of using new approach of using Hydraulic Work Over Unit (HWOU/Snubbing unit) to workover these wells.
Using HWOU for workover restoration time from the failure to restoring production has been reduced from ~2-3yrs to almost less than a year along with significant reduction in overall cost (more than 40% per well). This approach has been successfully applied to 2 wells till dates and upcoming workover will be done in similar manner.