Crude oil and natural-gas condensate are harder to get rid of.

ECONOMIST: Oil theft in Mexico

Onshore production means all well drilling and other equipment used in the onshore production, extraction, recovery, lifting, stabilization, separation or treating of petroleum and natural gas (including condensate).

FORBES: Just Tell the "Fracking" Truth

Unless a shale well finds a lot of condensate and natural gas liquids, it is uneconomic at this time.

FORBES: Energy XXI Coins Money Reworking Old Exxon Mobil Wells