In all, around 410 petroleum wells have been drilled
in Israel (including about 95 appraisal and development wells) since exploration commenced in the 1940's. The majority of early
exploration efforts were in the coastal plain, Negev, Dead Sea
areas and later offshore Mediterranean coast. Most of these earlier
wells were located on limited seismic of inferior quality or poorly
processed and were mainly targeted at shallower horizons or at
the Triassic or Permian in a southern Negev region interpreted
by Givot Olam to be of low prospectivity. The few Triassic wells
drilled in the northern prospective region were located on single
line anomalies totally off structure and could only be used for
stratigraphic information.
The first exploration drilling was carried out in
1947 on a gravity nose in the Heletz area south of Ashkelon. Almost
ten years later, the Heletz oilfield was discovered at that location
by the deepening of the original well. Shortly after, the Zohar
gas field was discovered in the northeast corner of the Negev.
During the 1960's,with substantial government financial support,
a large amount of seismic was acquired along with many geological
studies and geochemical surveys, predominantly in the areas around
the Heletz and Zohar fields although some regional data was acquired
at that time also. Following the 1967 war, less governmental support
was provided for exploration within the earlier areas of exploration
and efforts were focused on the recently accessible Gulf of Suez
fields. Around this time, an American consortium drilled six offshore
wells along the Mediterranean coast without making a commercial
discovery despite several good shows.
The oil price crisis of 1973 shifted the exploration
focus to large structures in deeper unexplored sediments. Oil
shows were encountered in Lower Jurassic limestones to the north
of Jerusalem, Triassic and Paleozoic in the northern Negev were
explored and the Jurassic near Zohar gas field produced oil at
low rates for a short time. In this period a large effort was
spent on the Sinai which resulted in the discovery of the Alma
oil field and Sadot gas field in the northern Sinai and encouraging
oil shows offshore. Exploration continued in the coastal plain
area and resulted in the discovery of the small Shiqma gas field
in Neogene and Ashdod oil field in Jurassic sediments.
Exploration in the Sinai terminated abruptly with
the signing of the Egypt Israel peace treaty in 1979 and exploration
efforts reduced due to low oil prices. Moderate levels of exploration
continued in the Dead Sea area with seismic acquisition, shallow
drilling and deepening of some existing wells which resulted in
a live oil recovery from Triassic in one deepened well but no
commercial discoveries. Additional drilling took place around
the Ashdod area for Jurassic carbonate reservoirs which resulted
in one small oil discovery.
At the end of 1985, OEIL ( later called INOC, Israel
National Oil Company-a government owned entity ) suspended all
drilling operations in order to carry out a comprehensive basin
analysis study over all of Israel. Only limited exploration work
continued by private operators including the drilling of two Jurassic
wells in the northwestern part of the Negev which gave oil shows
but no discoveries. INOC recommenced exploration around the Dead
Sea area where a large amount of asphalt oil shows encouraged
continued exploration without resulting in any commercial discoveries.
Substantial drilling occurred to test Triassic and
Permian plays in the Negev region without success. Seismic clearly
shows the Mesozoic thinning southwards onto the platform and therefore
the Negev area does not have the same Triassic or Permian potential
as in the central and northern area of Israel. Various Triassic
shows were encountered in the Hakanaim and Massada wells in the
Negev region. INOC recently made a small discovery at the Zuk
Tamrur field near the Dead Sea which is producing at 150-200 bbls/day
from the base Triassic, Raaf Fm in an extended production test.
The Emunah-1 well recently tested 39° API oil from the Permian
Saad Fm before watering out and flowed 800 bbls per day of 31°
API oil from the Lower Triassic Yamin Fm. The area of these recent
discoveries includes Massada, Gurim, Hakanaim and other small
discoveries which have produced small amounts of varying API gravity
oils from Permian, Triassic and Jurassic levels. The Dead Sea
area, unlike the Rosh Ha'Ayin area, was exposed to active fresh
water flushing probably from Early Cretaceous time. The oil found
in the Dead Sea area was probably generated very recently from
poor Triassic (Jurassic?, Cretaceous?) source rocks, but in very
limited amounts.
In addition, three wells were drilled during the
early 1990's offshore Israel and two of these tested oil. The
Yam-2 well, drilled due west of Gaash-2, is reported to have tested
500 bbls/day of oil from the Jurassic. The other well, Yam-1 to
the south, is reported to have tested 800 bbls/day and is likely
to be appraised by drilling in the future.
Rosh Ha'Ayin Area
Only a few Triassic tests have been drilled in the
northern or central part of Israel, none of which, until Meged-2,
were within the boundaries of L-244. Most of the previous 410
wells drilled were in the western coastal area, the eastern Dead
Sea area or the southern Negev area. The first four wells to reach
Triassic in central and northern Israel, Ramallah-1, Deborah-2A,
Gaash-2 and Atlit-1, were drilled almost entirely without the
aid of seismic. The Ramallah-1 well was drilled to the east and
the Gaash-2 well was drilled to the west of the Rosh Ha'Ayin structure.
Both wells were drilled to test the Jurassic and were deepened
to the Triassic for stratigraphic information.
The Triassic and Permian potential in central and
northern Israel associated with the extension of the Palmyra Rift
where several large oil and gas fields were discovered in Syria
in the Triassic during the 1980's, was more completely developed
and understood by Givot Olam in the early 90's.
Recent wells drilled in 1994, 1995 include:
a) Givot Olam's Meged-2 well which recovered oil
from the Mohilla Fm in L-244 and
b) the David-1 well to the southwest of Rosh Ha'Ayin,
reached T.D. at 6,000m. The well had a strong gas show at the
Base Permian Saad Fm but was not tested due to mechanical problems.
Since 1981, some 775 km of seismic lines have been
acquired over the Rosh Ha'Ayin area and several studies by independent
consultants confirmed the potential for both structure and prospective
carbonate facies. In the early 90's Givot Olam reprocessed almost
all of the existing seismic lines ( around 1150 kms, which is
now available on work station ) and totally reworked the play.
The results of the Meged-2 and David-1 wells have much enhanced
the prospectivity of the area and the chance to find commercial
oil and gas accumulations.
Exploration expenditure on the Rosh Ha'Ayin area can be split into two phases with around US $10.0 million being spent by Givot Olam on drilling the Meged-2 well, seismic acquisition, reprocessing and various studies between 1992 and the present and around US $30 million being spent by INOC ( and its predecessors ) on approximately 1000 km of seismic lines and two wells, Ramallah-1 and Gaash-2, drilled on the flanks of the Rosh Ha'Ayin structure prior to 1983.
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