Evaluation of limestone incorporated cement compositions for cementing gas hydrate zones in deepwater environments

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2017

Öğrenci: İNANÇ ALPTUĞ HIDIROĞLU

Eş Danışman: MAHMUT PARLAKTUNA, İSMAİL ÖZGÜR YAMAN

Özet:

One of the potential problems which must be overcome during oil or gas exploration in deepwater environments is to complete the drilling operations without decomposing the gas hydrates. Gas hydrates remain stable as long as the thermodynamic conditions are not changed. But, especially by increasing temperature during drilling operations, there is always a possibility of change in thermodynamic conditions, which will cause decomposition. Another factor which may disturb the thermodynamic conditions is the evolved heat during hydration of cement which is used to fill the annular space between the protective pipe, casing, and the wall of the well. In this study, CEM-I cement, API Class G cement and limestone were mixed with different proportions and 8 different blended cement compositions were prepared. The cement pastes were cured for ages of 1-day, 7-days and 28-days at 15℃ and in order to investigate the applicability of cement samples, compressive strength, heat of hydration, porosity and permeability tests were carried out. The results showed that the presence of an adequate amount of limestone in the blend decreases the heat of hydration of cement blends. On the other hand, increasing the amount of limestone affects compressive strength development of cement blends adversely. Additionally, increasing amount of limestone also increases the porosity of cement blends while the effect of limestone amount on the permeability is not significant. Even if permeability values show a slight increase with the increasing amount of limestone, they are still very low. At the end of this study, results indicate that limestone blended CEM-I and API Class G cements show better performance than neat CEM-I or API Class G cements for cementing low temperature formations where gas hydrates exist.