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Left top: A July 25, 1948, lab report strongly indicated the presence of hydrocarbons. Left middle: A June 12, 1951, flow-test report onGhawar’s first well at ’Ain Dar was very promising. Left bottom: Legendary Bedouin guide Khamis bin Rimthan was instrumental in guiding Aramco geologists to potential well sites throughout the Eastern Province. Above: a map showing the location of Ghawar“discovery” wells west of the Arabian Gulf.

Fall 2008 21

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22 Saudi Aramco Dimensions

The debut discoveries, following the signing of an

exploration concession agreement between Saudi Arabia

and Standard Oil Of California (Socal) in 1933, were

at Dammam (1938), Abu Hadriyah (March 1940) and

Abqaiq (December 1940).

These successes led in less than a decade to the astound-

ing realization that a number of

apparently independent, commer-

cially viable oil fields were, in

fact, all part of one mind-bending

mega-field — Ghawar.

Ghawar is divided into five

areas, discovered individually:

’Ain Dar (1948), Haradh (1949

— located in the southernmost

part of the field), ‘Uthmaniyah

(1951), Shedgum (1952) and

Hawiyah (1953).

The giant reservoir is 280 kilo-

meters long and 40 km wide,

encompassing 1.3 million acres.

Saudi Aramco continues to pump

about 5 million barrels of Arabian

Light crude oil from Ghawar

reservoirs every day. It also pumps

2.5 billion cubic feet per day (cfd)

of natural gas from the field in

association with the production

of oil, and another 4 billion cfd

of non-associated gas, produced

from independent gas reservoirs

beneath but not part of Ghawar’s

oil-bearing formations.

So, by all measures, Ghawar

— the “crown jewel” for Saudi

Aramco and the Kingdom —

is an awesome asset.

Ghawar has all the right stuff to

be a super producer: high porosity

of its reservoir rock, which means

there’s an abundance of rock pores, or spaces, for holding

oil; high permeability, meaning many natural channels

allowing oil to flow through the rock; valuable light rather

than heavy oil; and high recovery potential.

The original realization of Ghawar’s existence was

a kind of educated hunch.

In 1940, while the Abqaiq

prospect was being drilled, a

young geologist — Ernie Berg

— was spending his second field

season mapping adjacent quad-

rangles on the edge of the great

Rub‘ Al-Khali desert, or “Empty

Quarter.” Berg mapped the dry

river bed known as Wadi Sahaba

in the Haradh area and noticed

that it took a sharp turn to the

south from its normal east-west

course for no reason apparent

to the naked eye.

After measuring and plotting

a large enough area to see a

trend, it became apparent that

the wadi was diverted by a

broad, low-relief dome, the sur-

face expression of a much larger

subsurface dome or anticline.

Aramco geologist Max Steineke,

who was the driving force behind

the company’s first commercial

discovery two years earlier at

Well No. 7 in Dammam, came

into camp the next day and

agreed with Berg that the

Haradh structure was poten-

tially significant.

In fact, it turned out that

Berg’s map was the first to delin-

eate a structure in the Ghawar

field and was therefore what

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Above: Saudi Arabia’s King Abdulaziz Al Saud ushered in atransformational era by fully sup-porting the search for oil in hisKingdom starting in 1933. Topleft: Ernie Berg, at right, with fel-low geologist Tom Barger in the1930s, is credited with discover-ing the desert outcrops thathinted at giant Ghawar’s exis-tence. Middle left: ’Ain Dar No. 1,an early production well. Bottomleft: a desert exploration party inthe Ghawar area in the 1940s.

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Legendary Aramco geologistMax Steineke, above, backed the intuitions of fellow geolo-gist Ernie Berg that ultimatelyproved well-founded, as a seriesof seemingly independent fieldsproved to be one giant field,Ghawar. Top right and middle:Aerial views of ‘Udhailiyah, thenthe new base for South Ghawarfield operations, 1956. Bottomright: the Ghawar field’sHawiyah Gas Plant, 1999.

21911araD4R1.qxp:21911araD4R1 11/8/08 10:44 AM Page 24

Fall 2008 25

geologists would call the “discovery map” for that field. With

the onset of World War II, the difficulties of getting supplies

and the loss of men to the war effort, wildcat drilling was

suspended. However, a shallow-drilling campaign designed

to confirm geologic structures based on Berg’s and other geol-

ogists’ maps was continued. The shallow drilling confirmed

Berg’s subsurface anticline at Haradh and was continued

northward, confirming a continuous anticline stretching from

Haradh to ’Ain Dar and Shedgum. This anticline was dubbed

the En Nala anticline, meaning “The Slippers.”

After World War II and with the resumption of drilling,

the most obvious location to resume wildcat drilling was

the ’Ain Dar structure because of its proximity to producing

facilities at Abqaiq. ’Ain Dar No. 1 was completed in July

1948 and put on production in early 1951 at an extraordi-

nary rate of 15,600 barrels per day (bpd) of dry oil, mean-

ing without water contamination. ’Ain Dar No. 1 was a

significant discovery for Aramco, but nobody knew how

significant it would become.

Although a number of structures with apparent closure

had been delineated, and at least ’Ain Dar had proven to be

oil-filled, nobody openly suggested that the En Nala anticline

would prove to be one continuous field. Aramco engineers

wanted to drill a step-

out well, ’Ain Dar No.

2, about 12 km south

of ’Ain Dar No. 1, but

Steineke argued that

the next well should

be 185 km to the

south on the Haradh

structure first mapped

by Ernie Berg nine

years earlier. Steineke

prevailed.

Haradh No. 1 was

a successful wildcat

drilled in 1949. Next

came ‘Uthmaniyah

No. 1, which was

drilled in 1951. The Shedgum No. 1 discovery well was

drilled in 1952, followed by Hawiyah No. 1 in 1953. ’Ain

Dar No. 1, Shedgum No. 1, Haradh No. 1 and Hawiyah

No. 1 are still producing today.

These discoveries pointed toward the existence of one

continuous reservoir with a common oil/water contact,

which was designated as Ghawar Field in 1952.

Ghawar — the Bedouin originally called the pasturage

area “El Ghawar” — remains the largest single oil field on

Earth. Not only is Saudi Aramco getting most of its daily

oil production from Ghawar but also most of its daily raw-

gas feed.

The field’s production reached a zenith of 5.7 million

bpd by 1981 — a world record for continuous production

in a single field — but output was reduced later that decade

due to declining demand. Still, the field’s current, sustained

5 million bpd output is unrivaled.

Since its discovery, enormous Ghawar has kept oil ex-

perts on their toes. In mid-2007, the Ghawar Integrated

Assessment and New Technology (GIANT) team, an inter-

departmental group working on a long-term, visionary

endeavor to better understand and characterize the oil field,

came across an interesting finding while looking at ways

to maximize the

reservoir’s oil recov-

ery percentage. The

researchers found an

extensive micro-pore

system of hidden

passages in carbon-

ate rock, where a sig-

nificant percentage

of unrecovered oil

resides. Today, the

GIANT team is ana-

lyzing this newfound

potential and finding

ways to tap into the

as-yet untapped

world below. ■

Chart above shows the accumulative oil production over the years ofGhawar’s five discovery wells.

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After World War II and with

the resumption of drilling, the

most obvious location to re-

sume wildcat drilling was the

’Ain Dar structure because of its

proximity to producing facilities

at Abqaiq. ’Ain Dar No. 1 was

drilled in 1948 and flowed oil to

the surface during drillstem testing.

’Ain Dar No. 1 was put on

production in early 1951 at an

extraordinary oil rate of 15,600

barrels per day (bpd) — and is still

producing today more than 57 years

later, with the original well casings

and with the aid of best-in-class

reservoir management practices.

The well, amazingly, produced

“dry oil” for 49 years, before pro-

ducing its first water in 1999. Over

the years, this magnificent well has

produced 152 million barrels of oil

and is still producing 2,100 bpd

in 2008.

In 1949 Aramco engineers wanted

to drill a step-out well, ’Ain Dar

No. 2, about 12 km to the south

of ’Ain Dar 1; instead, a second

wildcat was drilled 185 km to the south at

Haradh. At that time, no one openly suggested that

the En Nala anticline would prove to be one con-

tinuous field. This possibility became very real

when the Haradh No. 1 wildcat struck oil in 1949.

However, because Haradh well was nearly

200 km south of ’Ain Dar production facilities

and therefore impractical to produce at the

time, Aramco had to wait 15 years to bring

it on-stream. In 1964, Haradh No. 1 was

finally put on production at an oil rate of

6,400 bpd. The well was shut in during the

mid-1980s due to low demand but resumed

production in 1990 at 6,700 bpd of dry

oil, after acid stimulation. Haradh No. 1

has produced more than 24 million bar-

rels of oil in its career, and continues to

produce in 2008 at an oil rate of 2,300

bpd with a watercut of only 1 percent.

‘Uthmaniyah No. 1 was important in establish-

ing that the En Nala anticline was oil-filled between

’Ain Dar and Haradh. This wildcat well was drilled

in 1951 and tested initially at 9,200 bpd. As with

the other Ghawar wells, oil gravity was in the range

of 33 degrees API (Arabian

Light Crude).

‘Uthmaniyah No. 1 was

brought onstream in 1956

and produced at an oil rate

of 11,300 bpd in its first

year. Located on the eastern

flank of ‘Uthmaniyah, this

well was the first of the

discovery wells to employ

a water shutoff to extend

dry oil production. This

discovery well has pro-

duced more than 20 mil-

lion barrels of oil.

26 Saudi Aramco Dimensions

1

2

3

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The Shedgum No. 1 discovery well was drilled

in 1952 to delineate the En Nala anticline to

the east of ’Ain Dar. The well struck oil in

the Arab-D carbonate and was later brought

on-stream in 1954 at an outstanding oil pro-

duction rate of 12,400 bpd, comparable to

’Ain Dar No. 1.

In 1968 the wellbore rock matrix was

acidized to improve the flow of oil from the

carbonate formation. In 1989 liners were

run across the open hole to proactively

address future water encroachment.

Recently, the oil production rate

was enhanced greatly for Shedgum No. 1

by recompleting the well with a horizon-

tal sidetrack complemented by inflow con-

trol device (ICD) technology. Not only was

the oil rate increased from about 1,000 bpd

to over 3,700 bpd, the watercut has also

been lowered significantly.

Shedgum No. 1 has produced more than 98

million barrels of oil over the last 55 years, and

the application of new technologies will keep

the well producing for years to come.

The final discovery well was Hawiyah No. 1,

which confirmed that Ghawar held oil be-

tween ‘Uthmaniyah and Haradh. Drilling

was completed in 1953, and the well came

on-stream in 1966 at 4,800 bpd of dry oil.

The well received an acid stimulation

treatment in 1977, with subsequent pro-

duction of 7,600 bpd. Hawiyah No. 1

has produced 51 million barrels of oil, and

continues to produce today at 4,600 bpd.

Since the discovery of the Ghawar field in

1948, Saudi Aramco has implemented

best-in-class field management practices

and leading technologies that have

evolved over the years. As a result,

Ghawar’s “magnificent five” discovery

wells have demonstrated extraordinary

performance with extended lifecycles and

outstanding oil recovery.

One of the first reservoir management

initiatives was gas re-injection in ’Ain Dar.

In 1958, King Sa’ud Ibn ‘Abd al-Aziz inau-

gurated the Gas Injection facilities in ’Ain

Dar. The primary purpose of this program

was to re-inject produced gas to sustain reser-

voir pressure. Gas injection commenced in

1959 and continued for 20 years.

Water injection began in Ghawar in 1964

to provide additional pressure support (i.e.

maintaining reservoir capacity to push oil

to the surface). This technology, known as

secondary recovery, provided a stepwise

improvement in pressure support, and

began the displacement of oil from the

outer edges of the Ghawar field toward

the central regions to sustain oil produc-

tion, as demonstrated by the phenomenal

performance of the discovery wells.

In 1995, a comprehensive 3-D seismic

campaign was conducted across the

Ghawar field. The seismic profiles pro-

vided vital information on

reservoir structure and distri-

bution of fractures, guiding

development and re-comple-

tions across Ghawar. This

information, for example, was

used in guiding the placement

of the horizontal well trajectory

for Shedgum No. 1.

The Ghawar discovery wells

are still producing today with

their original well casings. This

highlights the outstanding quality

of workmanship and materials.

Combined, the five Ghawar dis-

covery wells have produced nearly

350 million barrels of oil.

The discovery wells will con-

tinue producing oil, and at the

appropriate time Saudi Aramco will apply the latest best-in-

class technologies to further extend producing life and curtail

water production. ■

Fall 2008 27

4

(1) 1948 Letter to His Excellency Finance Minister Abdullah Sulaiman reporting that wildcat well ’Ain Dar No. 1 successfully flowed oil to the surface. (2 through 5) Original well completion drawings for Haradh No. 1, ‘Uthmaniyah No. 1,Shedgum No. 1 and Hawiyah No. 1. (6) The original Hawiyah No. 1 well resistivity log showing large oil column.

5

6

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