How much Oil is there in a Reservoir?

We are all used to diagrams like this:

Oil Reservoir

(hit your browser’s “refresh” button to see this animation again)

It seems as if there is a large cavern underground, where oil swishes and swirls, waiting to be sucked up via the production string. Dream on.

  • Oil is contained within rock. The porosity of the rock is variable, take an average of 20%.
  • Of the oil in the pores (called hydrocarbon in place), perhaps 15-60% is recoverable if you rely on the reservoir pressure ‘squeezing’ the oil into your production string (called primary recovery), and up to the surface. The rest either sticks to the rock, or is not recoverable when pressure is no longer available.

So, out of 1m3 (1000 kl) of rock, you get between 30-120 kl of oil during primary recovery.

How do we get more of the remaining oil out? That’s in an upcoming entry.




5 Responses to How much Oil is there in a Reservoir?

  1. shammy says:

    “How do we get more of the remaining oil out?”

    via secondary recovery methods i.e. water/gas flooding your reservoir!

    I have also heard of the WAG EOR method as being a means of tertiary recovery. From what I’ve recently learnt, Chevron is employing the use of WAG in its Rangely field operations in northwest Colorado, USA. They’ve been successful in maintaining relatively steady production rates and extending the life of the reservoir.

  2. Wata says:

    Hello, Shammy. I talk about Malaysian efforts at EOR in another entry.

  3. zzeed says:

    yeah… i think thats what xiom[m] is doing. whacky wag eor.

  4. Rig Rat says:

    Water injection,gaslift, ESP, SAGD (in heavy oil), gas cycling (gas wells) list goes on.

    Oil recovery using solution gas drive (primary recovery) is really small.

  5. Rig Rat says:

    We are using a ESP completions these days on older wells-deployed on CT. Like on really old oil wells in Sabah.

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