Bedrock, Source Rock, Cap Rock

The Tertiary aged Thrace Basin is the most prolific gas province in Turkey. It is known that the organic matter-rich shale sections of the Hamitabat, Ceylan and Mezardere Formations in the Thrace Basin are proved as an effective source rock generating hydrocarbons as a result of thermal maturation with increasing burial depth. On the other hand, Danişmen Formation comprising organic matter rich shale and coal could not reach sufficient maturation conditions for species throughout the basin.

Middle Oligocene- Lower Miocene aged deltaic Danismen and Osmancik sandstone levels have good- excellent reservoir rock properties and form independent reservoirs in horizontal and vertical directions for conventional Natural Gas Production in our Fields. Addition to the conventional reservoir levels, two different horizons are also economically productive and having unconventional resource potential, including the Upper Mezardere Siltstone and Teslimkoy sandstone. The shale levels between the mentioned reservoirs and the shale, claystone and coal layers of the Danişmen Formation located above have cap rock properties.

Stratigraphy

The unit observed on the surface in our Production Fields in the region is generally the Ergene Formation. Wells that are not drilled too deep, as they are targeted at Osmancık and Danişmen Formations, are generally at the depth of the Osmancık Formation. Stacked Teslimkoy Sandstone levels which are proved as productive tight gas reservoir in the Thrace Basin are not tested yet in our license areas. More than 500 m of Marine depositions including Teslimkoy and Kesan Formations have tight gas potential and several untested tight gas reservoirs in these levels definitely improves the unconventional gas reserve potential of our fields.

The formations observed, from oldest to youngest, in the wells and their general characteristics are as follows:

Osmancık Formation (Middle – Upper Oligocene)

The delta front of delta precipitation system of the Osmancık Formation often consists of sandstone with good-excellent reservoir rock properties and cap rock shales alternating with these reservoir levels.

Danismen Formation (Upper Oligocene – Lower Miocene)

The Danismen Formation is eroded from the top and is covered by the Ergene Formation with an angular unconformity contact. The unit delta plain and delta distribution channels product has claystone, milestone and sandstone lithology and contains coal bands at the bottom sections. The channel sands in the unit have good reservoir rock and claystone have good cap rock properties. It has a transitional contact with the Osmancık Formation below.

Ergene Formation (Upper Miocene – Pliocene)

The product of the continental environment is composed of conglomerate, sandstone, milestone and claystone. They are generally fluvial deposits and cover the Danismen Formation below with angular unconformity.