Well spacing optimization for Sulige tight sand gas field, NW China

Reasonable well spacing has been studied and assessed to increase the reserves and improve the recovery factor of the Sulige gas field, where the reserves controlled by single well are small. An evaluation methodology for optimizing well spacing in a tight sandstone gas field was established from five aspects including geologic model, drainage radius, interference testing, numerical simulation and economic benefits. The well spacing has been optimized using this method. Through geological modeling, the rational inter-well distance is estimated to be less than 600 m and rational well array distance should be less than 1 000 m. Results of drainage areas estimation reveal that the rational inter-well distance should be ranged from 400 m to 600 m. Analysis of interference well test shows that the low limit for inter-well distance is 400 m and the favorable well array distance is 600 m. Numerical simulation and economic evaluation shows that an inter-well distance of 500 m and well array distance of 700 m are favorable. It is concluded from the above five aspects that, in current economic and technological conditions, the well pattern with inter-well distance at 500 m and well array distance at 700 m is rational in the Sulige gas field, and it can improve the recovery factor to 45%. Key words: tight sand gas field, well spacing optimization, sand body scale, drainage area, economic evaluation, recovery facto