Water production often has a big impact on limiting oil production from prolific wells, especially those supported by aquifers. When it comes to deep High Pressure, High Temperature (HPHT) wells, managing water production becomes even more complicated due to the challenges that limit downhole tool functionality, made even more complex when the source of water is from a channel behind the casing. A limited number of solutions are available for scenarios such as these.

The subject well is located offshore in the Gulf of Suez and was drilled in 2010 to a depth of 14000 ft with a downhole temperature of 320°F and a reservoir pressure of 5700 psi. Due to complicated hole stability issues after drilling the 6 in hole, a 5 in liner could not be run to the well Total Depth (TD), so a 3 ½ in liner was run for over 1500 ft of the 6 in open hole section. This situation was far from ideal for a good cementing job, with the result being that the 3 ½ in liner was mostly uncemented, free pipe.

Despite the selective perforating being carried out a long way from the Oil-Water Contact (OWC), water production kept increasing until it reached 95% in 2022. Saturation and production logs run in 2011 & 2017 showed that most water was coming from high-quality zones through cement channels behind the liner. Isolating the water source was considered; however, there would have been a high risk of damaging oil-bearing zones if conventional techniques were used.

With emerging technologies and evolving chemistries gaining more reliability in the field, a team started to evaluate the various options to shut off the water production from behind the liner and rank them in terms of water isolation likelihood, operational risk & risk of damaging oil-bearing zones. The study focused on three possible solutions; shallow penetration polymer sealants, relative permeability modifiers (RPMs), and remedial cement operations. Coiled Tubing (CT) was chosen as the conveyance method to deliver the solution.

The result of the study concluded that a specific design and procedure using shallow penetration modified, organically crosslinked polymer (m-OCP) system with a high content of properly sized Loss Circulation Material (LCM) would succeed in blocking water zones and bridge the oil-bearing zones for later recovery with selective re-perforation. The operation was carried out in September 2022 and successfully isolated 3000 BWPD while increasing well production by 2500 BOPD. In addition, the well started to flow naturally, saving the need for lift gas to use on other wells and decreasing the scaling risk in the well.

A cost saving of approximately $1M was achieved in remediating this well. The alternative of efficiently drilling a new well to recover oil from the top low permeability zone would be estimated at $16M.

Shallow penetration polymer sealants can be a cost-effective option to treat flow behind casing in challenging conditions. Expanding to an entire field could significantly increase production and maximize zonal recovery.

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