Hoang Thanh Tung (1), Nguyen Pham Huy Cuong (2), Tran Hong Nam (3), Le Quang Duyen (4), Dao Thi Uyen (4) 1.Petrovietnam Drilling and Well Services Corporation (PV Drilling); 2.Bien Dong Petroleum Operating Company (Bien Dong POC); 3.Petrovietnam Exploration Production Corporation (PVEP); 4.Hanoi University of Mining and Geology (HUMG); Email: tunght@pvdrilling.com.vn