Pressure balance between the wellbore and formation is often quite sensitive due to narrow pore pressure and fracture pressure window. It gets more attention while drilling through fractured or vuggy rocks, which could easily attribute to downhole mud losses. Sealing the loss zone is of great concern, since it may take significant amount of resources before re-commence to drilling in a safe environment. GEOS has successfully cured a challenging thief zone with specially tailored LCM blends while drilling for a major operator.
Operatör tarafından yapılan ve ortalama 3000 m. üzeri derinliğe ulaşan sondajlarda katı ve sıvı atık toplamının ortalama 2,500 m³ seviyesinde olduğu ve oluşan bu atığın sondaj süresince muhafaza edilebilmesi için en az 800 m² yüzey alanına sahip çamur havuzu ihtiyacı doğduğu görülmüştür. Tarım arazilerinin maliyeti, tarım arazisi olmayan –dağ yamacı- bölgelerde ise lokasyon inşa maliyeti ve alan sıkıntısı lokasyon büyüklüğünde kısıtlayıcı bir etken oluşturmaktadır. Sondaj boyunca çamur havuzunda biriken bu atıkların akış testi öncesi boşaltılması ve bertarafı ise bir diğer operatör problemi olarak karşımıza çıkmıştır. Oluşan sıvı atıkların bertaraf öncesi diğer lokasyonlarda bulunan çamur havuzlarında depolanması ise çamur havuzlarının önceki sondaj atığı ve akış suları ile dolu olması sebebiyle mümkün olmamıştır.
Upon the investigation related with the drilling wastes of wells of Sis Enerji Üretim A.Ş. which reach minimum of 3,000 m. depth, it was observed that minimum 800 m² of surface area is needed to store an average of 2,500 m³ waste for each drilling operation. High cost of agricultural lands and constructional difficulties on steep terrains were interrupting factors choosing suitable location. Furthermore, high disposal costs were faced as another problem to empty the mud pits which were full of cuttings and liquid wastes before flow tests.
When drilling hot wells an oil base drilling fluid systems is usually the only option for oil and gas reservoir drilling. On the other hand, for geothermal reservoir drilling, the oil based systems cannot be an option due to reservoir and reservoir characteristics. HOT-DRILL water based drilling fluid provided stability and performance in a very challenging environment.
Wellbore stability is the main issue for most of drilling area. There are many types of formation has high risk for stability. Salt formation can be the most dangerous one. An oil base drilling fluid systems is usually the only option for salt drilling, because of its stability and minimum reaction with salt. On the other hand, due to high cost, the oil based systems can not be an option. A water based super saturated salt saturated polymer drilling fluid provided stability and performance in a very challenging environment. The case has a high core recovery record among the area.
Serpentine, which is a volcanic rock, caused drilling difficulties. Wellbore cavities and pack-off are generally observed problems which causes high torques, pressure build up at SPP and even loss of the well. To minimize well stability problems, modified stresscage system; STIFF DRILL D was improved and achieved in the serpentine section. The serpentine formation is the deepest and longest one in that area as well as in Turkey.