Petroleum Geology Integrated Study Of Block 102a/112 Of Chelif Basin In Algeria

Chelif Basin is located in northwest coast of Algeria and is about 9923 km2 square. It belongs to part of Tellian-Atlas and is near the Mediterranean. It is also a complicated Meso-Cenozoic petroliferous basin. As one of the earliest exploration breakthroughs of Algeria, the exploration history of Chelif basin began in the end of 19th century. However, the degree of exploration is low relatively. There is still need for the study of distribution characteristics of source rock, reservoir, cap rock and dominant hydrocarbon play.Guided by theories and viewpoints of sedimentology, logging geology, and geochemistry, the paper used extensive data including outcrop, seismic, logging, well log and geochemistry in order to make an integrated research on the structure, sedimentology and geochemistry of block 102a/112 in Chelif Basin. The results and understandings were as follows.1. There were three sets of source rock in Chelif basin. Two sets of source rock can be compared to the crude oil well, and they were mudstone and marl of Upper Cretaceous and Upper Miocene. Thermal evolution study on source rock indicated that source rock of Upper Cretaceous entered oil window in late Oligocene, source rock of Upper Miocene entered oil window in the period during late Miocene to early Pliocene.2. After the work on the plane distribution of sedimentary facies were done, and the reservoirs were classified, it was recognized that potential reservoirs were underwater distributary channel sandstones of (braid, fan) delta front.3. The main cap rocks were classified from the aspects of logging and drilling data. It was realized the best cap rocks of Chelif basin were mudstone, gypsum and carbonate rocks.4. Fault nose, fault block, fault anticline, fault anticline and overlapping stratigraphic trap developed mainly in south reverse structure belt; drape anticline, fault anticline developed mainly in central uplift belt, fault nose and overlying pinchout lithological trap developed mainly in southwest of central uplift belt; fault anticline developed mainly in north reverse structure belt. According to the balanced profiles, it was realized that most Miocene traps in Chelif Basin were formed during late Upper Miocene to early Pliocene.5. According to the geological risk evaluation of traps, traps belonging to classâ… , traps belonging to classâ…¡, and stratigraphic-lithologic traps were found on bottom of Lower Miocene and Upper Miocene.6. After analyses on the source-reservoir-cap combination of Chelif Basin, structure top maps of systems tract boundaries were made. Accoring to analyses of trap and migration period, two potential zones were finally determined, which could guide the next exploration.