أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
If we're talking about abandoned oil underground, then we're probably refer to oil that's hard to produce or extract by conventional means economically. There are always ways and means to extract oil that is either difficult to produce due to its quantitiies, being isolated in pockets, or very heavy for example by enhanced oil recovery and other methods. Economics play an important role in such decisions based on feasibility and investment climates. There is also unconventional oil that also requires special techniques to produce, and has its economics considerations.
