阿尔及利亚三叠盆地、韦德迈阿次盆地石油地质特征及油气勘探中应注意的问题

阿尔及利亚在区域上由两大单元组成,北部为撒哈拉阿特拉斯褶皱带,南部为撒哈拉地台。油气田主要分布在撒哈拉地台的三叠盆地和伊利兹盆地。在三叠盆地内已发现50多个油田和37个气田,石油地质储量达23×108t,天然气地质储量达4×1012m3。油气田中以超巨型的哈西迈萨乌德油田和哈西勒迈勒凝析气田最为著名。三叠盆地的烃源岩主要为下志留统Graptolitic组黑色页岩;韦德迈阿次盆地的烃源岩主要为志留系Fegaguria组深灰色—黑色富有机质泥岩。三叠盆地与韦德迈阿次盆地的储盖条件都比较优越,但油藏的埋深较大,且位于沙漠地区,在勘探上应注意“西气东油”的油气分布特征和坚持“立体勘探”的方法。

Characteristics of Petroleum Geology of Triassic Basin and the Subordinate Oued Mya Basin in Algeria and Suggests for Oil and Gas Exploration

Algeria is regionally divided into two major structural units: including the northern Saharan Atlas fold belt and the southern Saharan Platform. Oil and gas fields are mainly distributed in Illizi and Triassic basins of the platform. The Triassic basin is located in the eastern Saharan Platform while its subordinate Oued Mya Basin is just in the central part of Triassic Basin. More then 50 oil fields and 37 gas fields have been discovered in the Triassic basin with 2.3×109t and 4×1012m3 of oil and gas reserves in-place respectively. Among them, the largest oil and gas fields, Hassi Messaoud Field and Hassi R'mel Gasfield, sit respectively in the Hassi Messaoud Ride and Tilrhemt Dome in Oued Mya Basin. Source rock in Triassic Basin, main is the Lower Silurian Graptolitic black shale and that in Oued Mya Basin is organic-rich Silurian Fegaguria dark gray to black shale. Triassic Basin or its subordinate Oued Mya Basin has good reservoir$caprock condition and basic infrastructures as well as good exploration environment, but it has some unfavorable factors, including deep-buried reservoirs, desert and so on. It is suggested that exploration should pay an attention to six relevant aspects, such as "gas in the west and oil in the east" in hydrocarbon distribution, and keeping the method of tridimensional exploration, and so on.