Well Design to Drill the Undrillable

Application Answer: MetalSkin^® Solid Expandables

Challenge: Drilling and well engineers know that there is a physical constraint, as well as an economic limit, that defines the maximum number of casing strings that can be set to isolate individual hole sections in a well. This reality can become limiting as oil and gas exploration and production activity targets extreme environments in terms of well depth (and associated pressure and temperature regimes) and as development drilling proceeds in mature basins with depleted reservoirs.

Additional casing strings to isolate drilling hazards are necessary to drill through pressure transitions, tight pore-pressure fracture-gradient windows, depleted or overpressured zones, and unstable formations. The result is extreme well tapering, which makes it difficult or impossible to design wells economically that reach their intended reservoir targets with a suitable hole size.

Answer: Apply Weatherford's MetalSkin open-hole solid expandable liners or clads as a preplanned element of the well design or as a preemptive drilling contingency, allowing you to drill wells that seem “undrillable.” MetalSkin open-hole solid expandable systems can enable you to reach reservoirs, using larger casing sizes than previously possible, thus increasing the size of production tubing and associated production rates.

Expandables also can save money by slimming the well from surface down while still reaching the intended total depth with the optimal wellbore size.

Weatherford’s open-hole systems that help drill “undrillable” wells include:

• MetalSkin monobore open-hole clad system: selectively isolates trouble zones as they are encountered, allowing drilling to continue without sacrificing hole size or tying back to previous casing.
• MetalSkin monobore open-hole liner system: allows the well designer to extend a casing string without slimming the well profile.
• MetalSkin open-hole liner system: a solid expandable drilling liner that reduces well construction costs and provides an additional casing string while conserving hole size.

New-generation MetalSkin solid expandable systems for open-hole enable the well designer to mitigate drilling hazards and drill the “undrillable.”

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