Effect Of Compositional Change In Kuzey Marmara Reservoir On Storage Capacity

Abstract

Turkish Petroleum Company (TPAO) has served the first underground gas storage facility called as “Kuzey Marmara and Değirmenköy Fields Underground Gas Storage Facilities” to Turkey economy on 21.03.2007 where it was initially started to execute in 1996 by considering the need of gas storage facility of Turkey. The fields used in the scope of project are depleted gas reservoirs. Storage facilities consist of Kuzey Marmara and Değirmenköy Fields Gathering Points and a Shared Facility used for injecting gas to reservoirs and processing and serving the withdrawn gas to BOTAŞ Main Pipeline. Storage activity is mainly comprised of injection phase, injection of processed gas taken from main distribution line via shared facility, and withdrawal phase, production of mixture of injected processed gas with cushion gas. A storage period consists of withdrawal process following up injection process and original and injected gas have different compositions. It is observed that such compositional difference results composition change in withdrawn gas. In this study, percentage rate of change of withdrawn gas composition to original gas is determined by selecting Kuzey Marmara Reservoir gas composition as original composition before starting storage activity. Production amount has been determined at %5, %10 and %12 gas composition to original gas composition for each period. These production amounts are used for comparison for each storage period to get an idea about compositional change of reservoir. It has been observed from the tests performed when there is no operation (injection or withdrawal) that the pressure of each well changes simultaneously. Thus, it has been concluded that the measured pressure of any well represents the whole reservoir pressure characteristic. Hence, well no 8 in Kuzey Marmara has been selected as the pilot well and pressure of this well has been assumed to represent the reservoir pressure. The effect of changes in gas composition on the storage capacity has been examined by correlating the amount of gas withdrawn from the reservoir and the pressure attained on the injection period for each storage year (period). It has been anticipated to achieve significant results by making use of obtained data in the oncoming years in that study.