Overview of Libyan Geology

Libya is the fourth-largest country in Africa by land area and is bounded by the Mediterranean Sea in the north, bordered by Tunisia and Algeria to the west, Niger and Chad to the south, Sudan to the southeast and Egypt to the east. More than 90 percent of Libya is desert or semi-desert, and until oil was struck in the 1950s it had very low economic and strategic promise, according to the Society for Sedimentary Geology, other than that offered by its 1,770-kilometre coastline on the Mediterranean Sea.

=Geographical overview=

Historically, the country was divided into three primary geographical zones: Tripolitania in the northwest (covering 16 percent of the total land area), Fezzan in the southwest (33 percent), and Cyrenaica in the east (51 percent). In 1969 the revolutionary government officially changed the designation of the region Tripolitania to Western Libya, of Cyrenaica to Eastern Libya, and of Fezzan to Southern Libya, but during the 1970s the historical terms continued to be used frequently.

The country struggles with desertification and very limited fresh water resources. Less than two percent of the country receives enough rainfall for settled agriculture. Droughts are common throughout the country, and may extend to over two seasons.

=Geological Structure and Oil Producing Basins=

Libya has five major sedimentary basins, referring to low areas in the earth's crust where sediments accumulate and economically viable oil reserves are sometimes found. Four of these are major producers of oil. In order of importance, these are: Sirte, Ghadamis, Murzuq, and the Tripolitanian Offshore Basin. Libya has two additional non-productive basins, Al Kufra and the Cyrenaica Platform, respectively in the south-east and north-east of the country.

Sirte
The Sirte Basin, in the centre-east of the country, is the youngest and most important in Libya and contains 16 giant oil fields, defined as fields containing more than 500 million barrels of recoverable oil, while a giant gas field contains at least 3 trillion cubic feet (tcf) of gas. The Sirte Basin contains some 45 billion barrels of oil and 33 tcf of gas, or about 117 billion barrels of oil equivalent (boe). With 89 percent of all petroleum reserves discovered in Libya as of 2009, Sirte was ranked 13th among the world's petroleum basins and was considered the most prolific in north Africa. Sirte produces very light, sweet crude with a gravity ranging between 44° and 32° API and a low sulphur content between 0.15 and 0.66%.

Ghadamis
The Ghadamis Basin, in the north-west of Libya, covers about 390,000 square kilometres and encompasses portions of southern Tunisia and eastern Algeria. Ghadamis is a productive area with total recoverable reserves of over 3.5 billion boe, with a production of about 950 million boe as of 2009. The Ghadamis Basin is the site of the Wafa field, a key supplier of gas for the Western Libya Gas Project (WLGP).

Murzuq
Situated in the south-west of Libya, the Murzuq Basin straddles the boundaries of Algeria, Niger and Chad. Murzuq has reservoirs with over 5 billion barrels of oil equivalent. It is home to the Shararah and the Elephant.

Tripolitanian Offshore Basin
Situated off Libya's north-west coast, the Tripolitanian Offshore Basin is the site of the El Bouri field.

=References=