Planning LL with DNO

Falstaff (2/6-7 S) – Top hole

What happened:

After evaluating related risks of RIH with torque tool and stinger in one run – a decision was made to do a conventional stinger cement job without the torque tool. By running only stinger enabled to sting in to both the primary and secondary seal in the float collar. UV dye was mixed in the spacer and spacer volume designed so that when spacer was seen in return it was stopped pumping cement. Theoretically that would leave cement just below MLH. A sampling station was set up with UV boxes and return from well continuously tested for dye. Extra retarder was included in the Lead cement slurry – giving the possibility to run the torque tool after cementing – circulating out excess cement above MLH.

What was planned:

The plan for the 20” cement job was to run a torque tool with stinger – to sting into the upper seal in the float collar and simultaneously land off the torque tool in the 13 5/8” hanger profile in MLH. Cement the 20” casing through stinger, open wash port with torque tool and circulate any excess cement above MLH. This to ensure 20” and 30” casing not cemented together – making it more difficult during P&A pulling both strings together.

What was learned:

The space out between the stab-in stinger and torque tool is crucial for the planned method – performing the cementing and cleanout of excess cement in one run. If the space out is incorrect – risk of fail to sting into float collar or to land torque tool. If not stabbed into float collar – risk of over displacing shoe when washing through wash ports. TFMC circulating head is required for this type of cement job – required to be stripped over drill pipe with associated rigging and handling risk. If wash ports opened – no guarantee to be able to close – compromising the integrity of the surface casing. The cement job reliant on secondary seal only to be able to land out both the torque tool and sting in.

What actions are required:

For similar future operations its recommended to do a conventional cement job – decreasing the risk of loss of well. Extra retarder in the lead cement give the possibility to RIH with the torque tool after if cement is expected above the MLH.