Abstract: Based on the experimental and measured data, the positive effect of formation water on conservation of natural gas is discussed.The case study shows that first, the existence of pore water could change the pore structure of mud, increase its displacement pressure, decrease its diffusion coefficient, thus effectively prevent natural gas from leaking and diffusion out of reservoir; second, plentiful formation water provides good storage space for natural gas, and avoids escape of early generated gas, thus adding possibility of natural gas accumulation; third, the existence of formation water allows natural gas to be accumulated in forms of solution state and hydrate for shaping non-conventional gas pool. Therefore, formation water is favorable for extension of space of gas accumulation, hence enlarging the scope or area for natural gas exploration.

Key words: natural gas, conservation, formation water, effect