Tight Gas Development Within Thrace Basin, NW Turkey

Abstract

The Thrace Basin in northwestern Turkey contains up to 9,000 meters of Tertiary clastic sediments. To date over 400 BCF of gas have been produced mainly from conventional reservoirs. Within the southern portion of the basin, below approximately 600 meters depth, calcite cementation and compaction have severely reduced permeability within feldspathic litharenite sandstones. These tight gas reservoirs require hydraulic stimulation for economic production. Development of this resource consisted of a phased proof-of-concept strategy, initially focussed on exploiting structural traps followed by the pursuit of basin-centered gas. Within the past three years, 645 km² of 3D seismic has been acquired and more than 50 fracs have been executed in the southern Thrace Basin targeting middle Eocene to Oligocene turbidite and prodelta deposits of the Kesan Group, Mezardere Formation and Teslimkoy Member. Phases of the program included re-entering existing well bores and performing single stage fracs, performing multistage fracs in vertical well bores and the drilling of horizontal wells with up to ten frac stages. Initial production rates have ranged from 0.5mmcf/d to 5.0mmcf/d with varying amounts of water production. Regional geological and geophysical mapping as well as geochemical and pressure data suggest the possibility of an unconventional gas accumulation within the basin center. Within the Mezardere Formation, stacked delta slope fan complexes juxtapose both reservoir and source in an active hydrocarbon kitchen. The next phase of tight gas development in the Thrace Basin will be to evaluate this unconventional play concept. Tight gas development has the potential to yield several TCF of natural gas and provide meaningful domestic supply to Turkey, which is heavily dependent on natural gas imports.

AAPG Datapages/Search and Discovery Article #90194 © 2014 International Conference & Exhibition, Istanbul, Turkey, September 14-17, 2014