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. Despite of lesser and lesser new discoveries and most of the big oil fields are in declining phase, fast economic growth of Vietnam needs more energy. Among the Improved Oil Recovery (IOR) techniques, horizontal wells appeared to be a promising one in both short and long term of reservoir life.
Horizontal wells have a higher productivity and pay contact per well than that of vertical wells, thereby reducing the number of wells required to drain the reservoir. Horizontal wells allow operators to take advantage of highly heterogeneous reservoirs, especially those with fractures, or water and gas coning problems. As an injection well, a long horizontal well provides a large contact area, and therefore enhances well injectivity, which is highly desirable for enhanced oil recovery (EOR) applications. In this study, the efficiency of horizontal well will be evaluated by analyzing horizontal well performance. Both the advantages and disadvantages will be compared with those of vertical well. In assessment of the efficiency of horizontal well, both analytical and numerical solutions will be investigated.