Study on Well Pattern Optimization of Tight Sandstone Gas Reservoir with the Strong Heterogeneity

Sulige gas field, located in Ordos basin, is a representative and the largest unitization tight sand gas field in China, reserve quality more than 30000×108m3, the largest Gas-Initially-in-Place in China. The average reservoir thickness is about 9m, the porosity is 9%, and the permeability is 0.73×10-3μM2. After 8 years development, it is expected that the gas annual production will be over 200×108m3 by the end of 2013. The main types of He8-Shan1 reservoir of Permian system of in Sulige gas field are braided river sand bodies and meandering river sand bodies, which overlay vertically and composite laterally in the various period.The well pattern will directly affect the gas field recovery and economic benefits. The preliminary evaluation of Sulige gas field shows that, if recovery ratio increase 1%, gas production may increase by tens of billions cubic meter. It is obvious that gas recovery ratio is one of the keys to enhance the level of gas field development and benefit, and optimizing development well pattern is the most important element to improve the gas field recovery ratio. Changqing Oilfield Company has established three trial blocks since 2003 (Su6 encryption area, Su14 encryption area, Su14 three-dimensional test area). Around effective sand body anatomy and interference test, we have done a lot of researches and tests. In the paper, a lot of methods and technologies are applied to optimize well pattern in Sulige gas field, such as the geological knowledge database statistics, outcrop observation, well testing, fine description in the dense well space test areas, well interference testing, geological modeling and numerical modeling.