Online Journal for E&P Geoscientists

Taher, Ahmed Q.^*1; Al Suwaidi, Ahmed S.²
(1) Exploration, ADNOC, Abu Dhabi, United Arab Emirates. (2) General Management, ADMA-OPCO, Abu Dhabi, United Arab Emirates.

Shale oil potential is a consequence of the conversion of solid kerogen particles into liquid or gaseous compounds inside the source rock horizon. This transfer, which is a maturity-related process, will fill the early mature kitchen pore spaces with newly generated oil. Normally, increasing source conversion will increase the pressure inside the source strata resulting in the creation of a fracture network. These induced fractures will facilitate the primary migration of the generated oil out of the kitchen and into the carrier bed. However, in some kitchens, the carrier beds do not directly overlie the source rock and this will delay the primary migration and increase the accumulated oil inside the source rock strata. Also, the lateral migration will be hindered by the immature, solid kerogen in the areas surrounding the early mature kitchens.

Oil exploration from the source rock kitchens need to be focused on the areas that are characterized by rich organic matter content and it’s in the early stages of oil generation. Finding economically attractive oil accumulations in the source rock kitchen is linearly increasing with the increase of porosity values. The development of source rock porosity could be attributed to the low density of organic matter, source rock richness and the argillaceous nature of these source rock intervals. Also, the conversion of solid organic particles into liquid components will provide additional space for generated hydrocarbons.

The maturation modeling of the Cenomanian, Shilaif Formation indicated the presence of early mature kitchens in the offshore and southern onshore synclines. In some of these localized kitchens, significant quantities of oil were generated but not expelled into the surrounding structures especially in the southwestern onshore syncline. Similarly, the Oxfordian Diyab (Hanifa) Formation is prospective, mainly in the northern offshore area. In this area, the Diyab source rock did not reach the expulsion phase yet and the wells data of this area indicated the presence of potential oil accumulations in this area.