Tekirdağ doğal gaz sahasının yer altı gaz depolaması olarak modellenmesi

The Tertiary-age Thrace Basin is the largest gas producing onshore area in Turkey. Thrace region has both large and mostly small size natural gas fields. However, the gas producing fields in Thrace region are only producing less than one percent of the domestic demand. On the other hand, gas interruption in supply due to long-distance pipeline routes as well as political and technical reasons pose a risk to continuous gas demand of the country. Thus, gas storage in emergency situations or during the unexpected short term excess demand plays a key role in security of the country energy needs. As a result, converting of partially or fully depleted gas reservoirs to the underground gas storage is inevitable. Tekirdağ field is one of the biggest shallow gas reservoirs in Thrace region producing from deltaic Osmancik formation. Tekirdağ field was discovered in 1998 and despite of that it is close to fully depletion now, there is no precise and accurate OGIP estimation to date due to lack of data. In this study, firstly original gas in place (OGIP) has been estimated using static and dynamic data for the reservoir Unit-A and Unit-B. As a result of marial balance method, 452 psia and 473 psia of original reservoir pressure has been calculated for Unit-A and Unit-B respectively. Also, OGIP has been calculated as 32.1 bscf (909.0 million sm3) and 17.5 bscf (495.5 million sm3) for the reservoir Unit-A and Unit-B, respectively. Secondly, it has been worked on the modeling for underground gas storage. Thus, Tekirdağ gas field is designed for storage purposes using RUBIS simulator. In the first scenario, Tekirdağ field is simulated as a underground gas storage with already existing twenty two wells for Unit-A and eight wells for Unit-B. Secondly, mechanical skin has been applied to all wells. And finally, one horizontal well for each reservoir has been placed and investigated results of the all scenarios. In order to achieve the results, one year of storage cycle is planned as follows for Unit A and Unit-B; • Five months of injection period keeping the bottom hole injection pressure as original reservoir pressure. • One month of shut-in period. • Five months of production period keeping the surface flowing pressure at 145 psia. • One month of shut-in period.