As oil price is getting more volatile these days, O&G operators had to think outside the box and be innovative in optimizing well design that can contribute to reduction in overall well cost. Conductor casing or drive pipe design, is an aspect that was put into spotlist to offer significant cost savings.
Conductor casing string typically uses same pipe size and thickness from surface to the planned setting depth. The design is based on estimated safe working structural load that it will encounter post-installation. One of the design load is from the vortex induced vibration (VIV), an important source of fatigue damage on conductor casing and it will directly affect conductor design ie. Grade, size and wall thickness. As VIV only occurs across pipes in water, the conductor casing joints inside the soil/below mudline are not affected by VIV fatigue damage. Hence, a tapered conductor design was introduced, by combining 2 different conductor wall thickness above and below mudline, based on the VIV exposures across the string.
This paper discusses on the challenges from design, planning to execution stage, in installing the tapered conductor to the setting depths seamlessly, without compromising HSE and well structure, by adopting fit-for-purpose design that contributes to effective cost optimization