North Africa flapper valve milling
- Well type Gas
- Max. deviation 54,4° @ 9 567 ft (2 916 m)
- Min. restriction 4,437” @ 28 ft (8,5 m)
- Max. temperature 304°F (151°C)
- Max. pressure 3 812 psi
Deviated well conditions call for lateral thinking, so when a 54° deviated, gas well experienced a malfunctioning downhole flapper valve, the operator requested an innovative solution. To complicate interventions even further, the well had several operational challenges including limited wellsite access, temperatures up to 303° F (151°C), 4% H2S and 4 mol% CO2 content in addition to low reservoir pressure. Therefore, the client decided to apply Welltec®’s e-line conveyed milling solution to open the flow path of the well.
The intervention was carried out in a North African gas well. To mill out the closed and stuck 7”x 4,56” 13 Cr. steel flapper valve, Welltec mobilized a combination of a Well Tractor® 318 and a Well Miller® 318 toolstring. The Well Miller was activated at 9 567 ft (2,916 m) MD where it successfully milled through the flapper valve in approx. 40 minutes.
After the completion of the milling phase of the operation Welltec performed another run to set the Welltec® Access Assurance Sleeve (WAAS) in the milled out flapper utilizing the Well Stroker® 318. This access sleeve ensures that entry/reentry through the milled flapper valve can be accomplished easily each time. The operation was successfully confirmed by running a 3,25” gauge through the new access sleeve.
Apart from performing the intervention fast and efficiently, Welltec’s e-line solution was the only feasible method due to the size of the offshore platform. Heavier intervention methods like coiled tubing were not possible to mobilize because of the weather conditions plus the risk of reservoir damage due to the introduction of fluids.
Besma Sellami, Well Engineering Team Leader, BG Tunisia
Welltec® has successfully milled out the fluid loss control valve in order to increase flow and allow access to lower completion.