Batı Karadeniz’in Tuna Deltası’ndaki gaz hidratlardan farklı kuyu konfigürasyonlarında gaz üretimi
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Tarih
2023-07-28
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Yayıncı
Batman Üniversitesi Lisansüstü Eğitim Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Dünya genelinde; her geçen gün artan petrol ve doğalgaz ihtiyacının mümkün olduğunca yerli kaynaklardan karşılanması yönündeki faaliyetler yürütülmektedir. Bu kapsamda, Türkiye’nin özellikle Karadeniz'deki deniz alanlarında yapılan çalışmalar büyük bir ivme kazanmıştır.
Gaz hidratlar yakın geleceğin enerji kaynağı olarak düşünülmektedir. Bu da gaz hidratların dünya genelinde büyük rezerv potansiyelinden kaynaklamaktadır. Yakın zamanda Çin’de kil ve silt formasyonlarında ilk olarak yatay kuyu teknolojisiyle sondaj yoluyla gaz hidrat üretim testi yapılmıştır. Bu çalışmanın amaçlarından biri Karadeniz’de gaz hidratlardan gaz üretimi için, üretim kuyusu konfigürasyonunun etkisini TOUGH + HYDRATE (T+H) kodu ile sayısal modelleme ile araştırmayı amaçlamaktadır. Bu çalışmada hidratlarda iki farklı model çalışılmıştır (Hidrat içeren tek katmanlı homojen kum ve hidrat içeren çok katmanlı kum/kil).
İlk olarak, Batı Karadeniz'in Tuna Deltasındaki ortalama koşullarına göre iki varsayımsal rezervuar modeli oluşturarak kapsamlı bir literatür taraması yapılmıştır. Bu amaçla, çalışmada kullanılan gaz hidrat rezervuar özellikleri ile ilgili literatür verilerinden elde edilmiş, bazıları ise iki farklı varsayımsal gaz hidrat rezervuarından çıkan varsayımlardır. Temel olarak, iki farklı varsayımsal rezervuar modeli (Model 1 ve Model 2) 1500 m su derinliğinde oluşturulmuştur. Model 1'de, homojen hidrat tabakası (HBL), geçirimsiz bir üst tabaka ve geçirimsiz bir alt tabaka ile sınırlanmıştır. Ayrıca Karadeniz koşullarında, varsayımsal heterojen metan hidrat rezervuarları (ardanmalı kum ve kil tabakalarından oluşan heterojen bir tabaka- türbidit) oluşturulmuştur. Jeolojik modeller oluşturulduktan sonra, bu rezervuarlardan sayısal gaz üretim simülasyonları, T + H simülatörü ile farklı basınçlarda (3 MPa, 4 MPa ve 5 MPa) basınç düşürme yöntemi uygulanarak farklı (dikey ve yatay) kuyu konfigürasyonlarında gerçekleştirilmiştir. Daha yüksek basınç düşürme değişimi ile, gaz hidratlardan daha yüksek gaz üretimi elde edilmiştir. Ancak, belirli basınç değerlerinde (3 MPa'dan düşük) kuyu etrafındaki hızlı soğuma nedeniyle gaz üretim debisi düşmüştür. Model 1-a simülasyonlarının sonuçlarına göre gaz hidrat tam çözündükten sonra, orijinal rezervuar sıcaklığına ulaşmak için üst ve alt sınırlardan (tabakalardan) gelen ısı transferinin yüzlerce gün sürmesi gerektiğini aynı zamanda homojen hidrat içeren kumlarda (Model 1-a) gaz hidrat çözünmesiyle açığa çıkan su, yerçekimi etkisi nedeniyle HBL’nin tabanında biriktiği gözlenmiştir. Model 1-b gaz hidratlarından 245 m'lik yatay kuyudan gaz üretimi, ilk üretim periyodunda (100 günden 200 güne kadar) dikey kuyuya göre avantajlıdır. Ancak daha sonra dikey kuyu kullanıldığında gaz üretimi daha avantajlı olmuştur. Model 2-a ve Model 2-b gaz hidratlarından (alternatif hidrat içeren kumlar/killer) elde edilen gaz üretimi, homojen hidrat içeren kum katmanlarına kıyasla oldukça karmaşıktır. Bunun için hidrat içeren kum katmanlarından gaz üretimi, hidrat içeren kil katmanlarında gaz üretiminden daha hızlı olduğu görülmüştür. Düşük geçirgenli hidrat içeren killer üzerinde, HBL'nin tepesinde 245 m'lik bir yatay kuyuyla basınç düşürme simülasyonları uygulandığında, HBL'de etkili basınç azalımını önlemiştir. Böylece Model 2'de dikey kuyu üretimi ile daha yüksek gaz üretimi elde edilmiştir.
All over the world; activities are carried out to meet the growing needs of oil and natural gas from domestic sources as much as possible. In this context, studies in the sea areas of Turkey, especially in the Black Sea, have gained great momentum. Gas hydrates are considered “near-future energy resources” due to their vast existence all around the world. This is due to the huge reserve potential of gas hydrates worldwide. Recently, China has tested gas production from methane hydrate-bearing clayey silts via horizontal well technology for the first time. One of the aims of this study is to investigate the effect of well configuration for gas production from gas hydrates in the Black Sea by numerical modeling with TOUGH + HYDRATE (T+H) code. In this study, two different models were studied in gas hydrate reservoirs in the conditions of the Black Sea (Single-layer homogeneous sand containing hydrates and multi-layered alternating sand/clay layers containing gas hydrates). Initially, an extensive literature review was conducted to create two hypothetical reservoir models representing the average conditions of the Black Sea. For this purpose, some of the parameters were obtained from the literature data related to the Danube Delta of the Western Black Sea and some of them were assumed to create two different hypothetical gas hydrate reservoirs. Basically, two different hypothetical reservoir models (Model 1 and Model 2) were created at a water depth of 1500 m. In Model 1, a single hydrate-bearing layer (HBL) is bounded by an impermeable overburden layer and an impermeable underburden layer. Moreover, hypothetical heterogeneous methane hydrate reservoirs (hydrate-bearing sand layer and hydrate-bearing turbidite) were formed in the Black Sea conditions. After forming these geological models, numerical gas production simulations from these reservoirs were conducted in different wellbore configurations (vertical and horizontal) by applying depressurization at different pressures (3 MPa, 4 MPa, and 5 MPa) with T + H simulator. With a higher depressurization rate, higher gas production was obtained from gas hydrates. However, at certain pressure values (less than 3 MPa), the gas production rate decreased due to fast cooling around the well. As seen in the results of Model 1-a simulations, after the complete gas hydrate dissociation, hundreds of days were needed to reach the original reservoir temperature by the heat transfer from boundaries. Water released with gas hydrate dissociation in homogenous hydrate-bearing sands (Model 1-a) moved through the bottom of HBL because of the gravitational effect. Gas production from Model 1 gas hydrates via 245 m-horizontal well is advantageous for the first production period (100 days to 200 days) compared to the vertical well. However, later, gas production with the vertical well became more advantageous. Gas production from Model 2 gas hydrates (alternating hydrate-bearing sands/clays) is quite complex compared to homogenous hydrate-bearing sand layers. Gas production from hydrate-bearing sand layers was faster than gas production in hydrate-bearing clay layers. Low-permeable hydrate-bearing clays avoided effective depressurization in HBL as depressurization simulations were provided with the 245 m-horizontal well in the top of HBL and near the bottom of HBL. Thus, higher gas production with the vertical well case was obtained in Model 2.
All over the world; activities are carried out to meet the growing needs of oil and natural gas from domestic sources as much as possible. In this context, studies in the sea areas of Turkey, especially in the Black Sea, have gained great momentum. Gas hydrates are considered “near-future energy resources” due to their vast existence all around the world. This is due to the huge reserve potential of gas hydrates worldwide. Recently, China has tested gas production from methane hydrate-bearing clayey silts via horizontal well technology for the first time. One of the aims of this study is to investigate the effect of well configuration for gas production from gas hydrates in the Black Sea by numerical modeling with TOUGH + HYDRATE (T+H) code. In this study, two different models were studied in gas hydrate reservoirs in the conditions of the Black Sea (Single-layer homogeneous sand containing hydrates and multi-layered alternating sand/clay layers containing gas hydrates). Initially, an extensive literature review was conducted to create two hypothetical reservoir models representing the average conditions of the Black Sea. For this purpose, some of the parameters were obtained from the literature data related to the Danube Delta of the Western Black Sea and some of them were assumed to create two different hypothetical gas hydrate reservoirs. Basically, two different hypothetical reservoir models (Model 1 and Model 2) were created at a water depth of 1500 m. In Model 1, a single hydrate-bearing layer (HBL) is bounded by an impermeable overburden layer and an impermeable underburden layer. Moreover, hypothetical heterogeneous methane hydrate reservoirs (hydrate-bearing sand layer and hydrate-bearing turbidite) were formed in the Black Sea conditions. After forming these geological models, numerical gas production simulations from these reservoirs were conducted in different wellbore configurations (vertical and horizontal) by applying depressurization at different pressures (3 MPa, 4 MPa, and 5 MPa) with T + H simulator. With a higher depressurization rate, higher gas production was obtained from gas hydrates. However, at certain pressure values (less than 3 MPa), the gas production rate decreased due to fast cooling around the well. As seen in the results of Model 1-a simulations, after the complete gas hydrate dissociation, hundreds of days were needed to reach the original reservoir temperature by the heat transfer from boundaries. Water released with gas hydrate dissociation in homogenous hydrate-bearing sands (Model 1-a) moved through the bottom of HBL because of the gravitational effect. Gas production from Model 1 gas hydrates via 245 m-horizontal well is advantageous for the first production period (100 days to 200 days) compared to the vertical well. However, later, gas production with the vertical well became more advantageous. Gas production from Model 2 gas hydrates (alternating hydrate-bearing sands/clays) is quite complex compared to homogenous hydrate-bearing sand layers. Gas production from hydrate-bearing sand layers was faster than gas production in hydrate-bearing clay layers. Low-permeable hydrate-bearing clays avoided effective depressurization in HBL as depressurization simulations were provided with the 245 m-horizontal well in the top of HBL and near the bottom of HBL. Thus, higher gas production with the vertical well case was obtained in Model 2.
Açıklama
Anahtar Kelimeler
Karadeniz, Gaz Hidratlar, Sayısal Simülasyon, Yatay Kuyu, Dikey Kuyu, Metan, Black Sea, Gas Hydrates, Simulation, Horizontal Well, Vertical Well, Methane
Kaynak
WoS Q Değeri
Scopus Q Değeri
Cilt
Sayı
Künye
Ubeyd, İ. M. (2023). Batı Karadeniz’in Tuna Deltası’ndaki gaz hidratlardan farklı kuyu konfigürasyonlarında gaz üretimi. (Yayınlanmamış Yüksek Lisans Tezi). Batman Üniversitesi Lisansüstü Eğitim Enstitüsü, Batman.
