File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎194r] (410/522)

PART 7.—THE PROSPECTS OF OBTAINING PETROLEUM.
(31) General Remarks .—Before setting down the most important deductions
which follow logically from the evidence already submitted, it may be well to
state exactly what the Petroleum Geologist can and what he cannot do. This
depends almost entirely on the amount of Geological evidence available in the
particular locality ; at iVaft Khana, for instance, the strata are sufficiently well
exposed for the form of the anticline there and the positions of the possible oil
to he accurately determined. He can therefore here forecast with precision
everything except the quantity of oil, and after the drilling of two or at the
very outside three locations, he can finally pronounce judgment on some
hundreds of square miles in this vicinity. On the other hand without previous
Geological investigation a dozen wells might be drilled and still the oil be missed,
in fact this would be very probable, since it would seem most natural to com
mence drilling at the seepages.
The region of Hit is more difficult for the Petroleum Geologist, since here
almost everything which he wishes to see is covered and hidden* beneath recent
formations and desert. Full and complete information cannot he obtained,
but a knowledge of the neighbouring country and the few isolated important
facts which can be gathered locally, enable him to make very definite recom
mendations based on relevant, if meagre, Geological data.
(32) Naft Khana—T \\q three conditions essential for a productive oilfield,
apart from the existence of oil, are :—
A Reservoir Rock to contain the oil.
Suitable structure to concentrate the* oil.
A Cap Rock to prevent the escape of the oil.
The porous sandstones and limestones of the Lower Ears Group, already
described in Section 6 , leave nothing to be desired as reservoir rocks. The latter
at Maidan-i-Naftun give enormous productions and they do not break down
and choke and bore holes, nor are the sandstones likely to do this. The oil of
Naft Khana being of low Specific Gravity and low Viscosity will flow easily
through these rocks and should give a steady production.
The form of the anticline at Naft Khana is ideal for the collection and
storage of petroleum, but it will not give an indefinite area of ground for drill
ing because it pitches down in both directions along the axis, and because the
inclination of the gentle flank is sufficiently steep (15 degrees) for depth to
increase rapidly with distance from the axis. The drilling area would be a
long relatively narrow strip parallel to and adjoining the anticlinal axis on the
North-East side.
The thick succession of clay shales which aggregate 65 per cent, or more
of the Lower Ears Group, are absolutely impervious to oil, at any rate apply
ing the term practically rather than scientifically, since there is no such thing
as absolute impermiability. Any oil imprisoned in an anticline covered by
those clays would be as effectively sealed up as possible, and its escape would
be well nigh an impossibility.
All the conditions for the storage of the oil being perfect, there remains
only the consideration of the prospects of the existence of such oil in commer
cial quantities. The prolific nature and extent of the seepages already described
is alone sufficient to prove that we are dealing with something more than a
purely local and sporadic occurrence of oil. There can be no doubt that surface
shows of such magnitude necessarily involve a large supply of oil beneath, on
the other hand the argument naturally presents itself that such large seepages
may have considerably depleted the main supply. While it is impossible to
prove this hypothesis to be fallacious, there are other considerations which more
than counterbalance it.
It must be remembered that, possibly contrary to popular belief, a fault
like that at Naft Khana is in no sense an open fissure. In Appendix A are
added some simple calculations showing that at a point 2,000 feet below the
surface of the ground the pressure tending to keep the fault closed, i.£., pressure
normal to the fault plane surface, is 50*7 tons per square foot due to Gravity

File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎194r] (410/522)

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File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎194r] (410/522)

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