File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎194v] (411/522)

12
alone, without any horizontal thrusting stress. If the folding motion is actually
continuing the minimum pressure tending to close any possible fault fissure is
130 tons per square foot. The precise intensity of this pressure^ which can
under no circumstances be less than 50‘7 tons per square foot at this point, will
probably fluctuate between the two figures, as presuming horizontal folding
effort to be still active, a maximum would gradually he reached culminating in
relief by slight motion with consequent drop of pressures. The forces enu
merated are all control by Gravity and therefore increase from zero at the
surface in direct proportion to the depth.
It will be seen then that in unresistant beds like clays and gypsum there is
no possibility of an open fissure. The fact that oil does escape along the fault
plane shows, not so much the existence of passages along this plane, as the
perfection of the sealing in of the oil away from the fault. At the same time
it is not surprising that the oil escapes along the fault plane, as even without any
open fissures at all, it still presents a less formidable barrier than the unbroken
beds.
Another point in favour of the underground supply not being exhausted is
the freshness of the shows and the absence of any weathered remains of oil
rocks. The latter would be indicated both by a rotted appearance of the rock
and by the presence of thinly disseminated sulphur which is often left after all
sign of the actual oil has vanished.
The highest seepage found occurs 200 feet below the top of the Lower Pars
Group, and from here to the fault is another 400 feet of beds with various
shows of oil on the gentle flank of the anticline, so we have by mapping a
proved petroliferous phase between 200 feet and 600 feet below the top of the
Lower Pars Group. Some of the seepages on the fault may be due to these beds,
but the majority of them come from deeper horizons, and most probably not from
one but from various horizons. A well drilled would therefore pass several shows
of oil which should increase with depth on account of the more effective sealing
of the deeper reservoir rocks.
A brisk evolution of gas was, as already stated, observed at some of the
seepages. This is always a good sign as it indicates underground gas which will
supply the pressure necessary for flowing wells.
The Anglo-Persian Oil Co.’s Maidan-i-Naftun field might be quoted as
analogous to Naft Khana in that there also the productive area is bounded by a
reversed fault along which occur seepages of extraordinary magnitude, far
exceeding even those of Naft Khana. If Naft Khana has large reservoirs of
oil it will not be as big a field as Maidan-i-Naftun on account of the much
narrower crestal area of the anticline, but even so it might still be an oilfield of
considerable magnitude.
Everything considered then, the copious oil seepages are much more likely
to be a guarantee of the existence of stores of underground oil than of the
depletion of this oil. Moreover Naft Khana is an almost ideal example of the
conditions necessary for oil production. Geologists will rarely find a better site
in which to locate a first test, as there is every possible factor in favour of
getting oil and not a single item of evidence against. It is inconceivable that
the locations chosen can be drilled without obtaining some sign of oil, and
although the all-important question of quantity can only be settled by the drill,
the indications which exist, while they could never be an infalligible guide on
this the only speculative point, are nevertheless of an entirely satisfactory
nature.
(33) The test location. —Three locations for drilling have been chosen for
depths of 100 feet, 1,500 feet and 3,000 feet, situated respectively at distances
of 450 feet, 1,200 feet and 1,850 feet from the anticlinal axis, and clear of the
fault.
No. 1 location for 400 feet is merely suggested as a temporary or prelimi
nary test, if a portable rig were available, as it would probably obtain
some oil.
A well drilled on No. 2 location would enter oil bearing strata within the
first 400 feet, and would be suitable for testing all oil horizons down to a dep h

File 1450/1919 ‘Mesopotamia & Kurdistan: Geological Reports on’ [‎194v] (411/522)

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