Ordovician Undiscovered Resources in South Hassi Messaoud. Ordovician Hamra Quartzite, an Example of Tight Oil Hassi Messaoud Basin (Algeria)

Daoudi, Nour Eddine (Sonatrach)



Tight oil production will change in the coming decades. The last positive results have opened new opportunities as source of renewal production, using unconventional techniques which are used in conventional fields.

The Hassi Messaoud area is located on the central Sahara and is well known as a major oil production in Algeria.

Eroded by the hercynian unconformity on the Hassi Messaoud field, the Ordovician reservoirs (mainly the hamra quartzites) forms a ring around the Hassi Messaoud dome and represent an oil play with a high potential. Recent drilling in the South of Hassi Messaoud dome has discovered significant oil production in the Ordovician Hamra Quartzite and during the last decade, many discoveries have been made in the, East and South flanks of the Hassi Messaoud dome. In many wells, the oil production is related to the fractured reservoir located in the Hamra Quartzites subcrop belt. Mainly these oil fields are Hassi Terfa, Hassi D’Zabat, Hassi Guettar and Hassi Toumiet. Important volumes of oil in place have been proven.

The reservoir qualities of Hamra Quartzites vary because of diagenetics effects. Most of the log data and core samples show that the potentiality of Hamra Quartzites is a modest reservoir due to the effect of cementation

This reservoir is sourced from the Silurian shale which is the main hydrocarbon source rock across the most of the Saharan platform. In the study area the Silurian shale is well developed in the North and the West of the Hassi Messaoud dome.

The 3D seismic surveys acquired in the area with a fold and field parameters allowing a good resolution, were the decisive tool which modified totally our understanding and knowledge about the structural aspect and at less degree the stratigraphic components of the area.

Combined lithologic and stratigraphic traps are the predominant hydrocarbon accumulation for Ordovician reservoirs. Nevertheless the main risk for the petroleum play elements is related to the fractures development.