A review of Carboniferous, Permian and Middle Triassic paleoenvironmental linked with Thermal maturities interpretation of A1-9 well, Concession 9, NW Libya
الخلاصة
The present work deals with the paleoenvironmental and hydrocarbon potential of the lithostratigraphic succession in Carboniferous, Permian and Middle Triassic sediments in the north west Libya. Data presented in this paper are based upon a detailed subsurface lithological characteristics from ditch cutting samples and involving electric logs (gamma-ray) linked with palynofacies interpretation. The sedimentary section of this area ranges in age from Upper Paleozoic rock to Triassic. Early Paleozoic rocks have not been found in the studied well (A1-9), these rocks were eroding during the Late Carboniferous and Early Permian time. During Latest Permian and earliest Triassic time evidence for major marine transgression has occurred. From depths 5930-5940 feet, to 10800-10810 feet, the TAI of the Al Guidr, the Bir Al Jaja Al Uotia, Hebilia and the top varies between 3+ to 4- (mature-dry gas). This interval corporate the rest part of the Dembaba Formation. From depth 10800- 10810 feet, until total sediment depth (11944 feet Log) which corporate the rest of the Dembaba and underlying equivalents of the Assedjefar and M΄rar Formations and the underlying indeterminate unit (Hasaouna Formation), the TAI varies between 4 and 5 (dry gas-black & deformed). The environment of deposition and the degree of thermal maturation has allowed the A1-9 well to become a key reference section in NW Libya from which correlations can be carried out.