Chapter nine
Saudi Arabia Petroleum Systems
Introduction
Three a really extensive, overlapping petroleum systems of Paleozoic, Jurassic, and Cretaceous age (fig.
1) have been recognized on the eastern half of the Arabian Peninsula. Source, reservoir, and seal rocks of
great geographic extent characterize each of these prolific hydrocarbon-producing systems of the eastern
Arabian Peninsula.
An estimated two-thirds of the world’s known ultimately recoverable oil is within, and adjacent to, the
Arabian-Persian Gulf, where a thick sequence of sedimentary rocks was deposited in a really extensive
basins along the eastern and southern parts of the Arabian Peninsula.
The central Arabian sub-basin portion of the Arabian Peninsula encompasses the Greater Ghawar Uplift
Province (figs. 2) and portions of adjacent geologic provinces along the east-central Arabian Peninsula.
The central Arabian total petroleum systems of Paleozoic and Jurassic age contribute most of Saudi
Arabia’s 261 billion barrels of proven oil reserves, more than one-fourth of the world total.
Although Saudi Arabia has about 80 oil and gas fields, more than half of its oil reserves are contained in
only eight fields. Two of these eight fields are classified as the world’s largest oil fields, both located
within the Greater Ghawar Uplift Province of this report. Ghawar field, Saudi Arabia, produces both oil
and gas from the Jurassic and Paleozoic systems and has estimated known reserves of about 115 BBO and
remaining reserves of about 70 BBO. Safaniya field, the world’s largest offshore oil field, has estimated
reserves of 19 billion barrels.
Immediately south of the Greater Ghawar Uplift Province, and in the Rub ‘al Khali Province, a Paleozoic
total petroleum system encompassing the Rub ‘al Khali Basin is sourced by the same Lower Silurian
organic-rich shale.
Total Petroleum Systems (TPS) In Saudi Arabia
The Greater Ghawar Uplift Province consists of:
1)
2)
1)
2)
3)
1)
2)
The Central Arabia Qusaiba-Paleozoic TPS.
The Arabian Sub-Basin Tuwaiq/Hanifa-Arab TPS of Jurassic age.
Structures that trap hydrocarbons in these systems are mostly:
Large, gentle anticlines.
Salt domes that.
Structural traps resulting from a combination of these two processes.
Major tectonic events that created these structures resulted from:
Early Zagros rifting during the Early Triassic.
Alpine tectonic episodes that occurred during the Late Cretaceous and middle to late Tertiary.
Total Petroleum Systems:
1) Hydrocarbons of the Central Arabia Qusaiba-Paleozoic TPS are sourced mainly by organic-rich, socalled “hot shale” that occurs in the basal part of the Lower Silurian Qusaiba Member of the Qalibah
Formation.
Oil and gas are produced mainly from sandstones of the Permian Unayzah and Devonian Jauf
Formations, and from basal transgressive marine sandstones and cyclic, dolomitic shelf-carbonates of the
Late Permian Khuff Formation.
2) Oil of the Arabian Sub-Basin Tuwaiq/Hanifa-Arab TPS are sourced by organic-rich, marine
carbonates of the Jurassic Tuwaiq Mountain and Hanifa Formations. Oils were generated and expelled
from these source rocks beginning in the Cretaceous at about 75 Ma.
Hydrocarbon production is from cyclic carbonate-rock reservoirs of the Arab Formation that are sealed by
overlying anhydrite. Two assessment units are also recognized in the Arabian Sub-Basin Tuwaiq/HanifaArab TPS that are similarly related to structural trap style and presence of underlying Infracambrian salt.