Oil wells, when drilled, are lined with metal casings that support the surrounding geology and prevent gas, oil and water from mixing in the well.
(Oil wells; are lined; with metal casings; T:when drilled) (metal casings; support; the surrounding geology) (metal casings; prevent; gas, oil and water; from mixing in the well)
Oil wells metal casings metal casings
are lined support prevent
with metal casings T:when drilled
the surrounding geology
gas, oil and water from mixing in the well