After several discoveries of oil and gas in fractured basement reservoir such as White Tiger, Dragon, Aurora and Ruby in 1990s, the basement on the continental shelf of Vietnam has become a major target for domestic and foreign oil companies. Oil produced from basement is accounted for more than 90% of the total produced oil. Due to lesser and lesser new discoveries and most of the big oil fields are in declining phase, the Improved Oil Recovery (IOR) methods are bringing advanced technological solutions to boost oil recovery from mature fields, geologically complex low permeable and fractured reservoirs in the future. Among the IOR techniques, horizontal wells appeared to be a promising one in both short and long term of reservoir life.
Horizontal well (HW) has a higher productivity and pay contact as increase the length of well, thereby reducing the number of wells required to drain the reservoir. In the case study presented, the efficiency of horizontal well will be evaluated by analyzing horizontal well performance. Both analytical and numerical solutions will be investigated. A 3D numerical model of the South-East Dragon field was set up with five production wells and one injection well that is known as a base case. Then running base case is to find the appropriate places for putting new well. Ten interesting scenarios are presented in this paper where the horizontal well is analysised both HW location sensitivities and HW length sensitivities. In addition, this research described a step-by-step procedure that can be used when performing an economic analysis of a horizontal well project. The results from the case study indicate that a combination of factors including total economic, analytical and numerical simulation is required to optimum horizontal well length in the fractured basement reservoir of South-East Dragon oil field in Viet Nam.