The client drilled an exploration well from a semi-submersible rig at the Haltenbanken area in Norway. After an initial discovery in the first vertical wellbore, a requirement arose from the license partners to drill a geological sidetrack to appraise the discovery further. A long reach target required a kick off from inside the 13 3/8” casing high up in the well.
The operator decided to plug the vertical wellbore permanently with balanced cement plugs. A cement plug was set across the 13 3/8” casing shoe, and the crew ran in hole with a casing milling assembly. A casing window was milled above the top of hard cement, and the well was successfully kicked off with a rotary steerable BHA.
The drill crew took precautions before the milling, in order to protect the flowlines, shakers and mud pumps from steel cuttings. A new effective MFF® (Magnetic Mud Filter) was installed in the flowline. However, very small amounts of fine steel particles were recovered on the surface, as most of the steel cuttings was recovered downhole on the Innomag® string magnets.
The use of effective magnets downhole and on surface prevented plugged flowlines, damage to shakers & mud pumps, and general contamination of steel particles in the BOP and surface mud circulation systems. This reduced the risk for lost time and money for the operator, and expensive equipment damage for the drilling contractor.
