Abstract: This paper carried on deep analysis on water issues in the gas drilling in Sichaun Dayi area. It studied the working area typical water layer based on the water data in the early 4 regions gas drilling, established Novack phase diagram using a new method of layer water, made preliminary forecast in accordance with the phase diagram of the water layer which has been confirmed by drilling. The water samples collected from gas drilling isn't easily effected by drilling fluid and mixed with multi-layers, these advantages can truly reflect the original formation water features and has high reliability. Accordingly Steve butterfly oil and gas field development map can provide a certain reference to on the follow-up, the map can be made as a standard mapthe of water chemical features in Dayi area , which provides a better guide to the development of the drilling program, casing design, engineering failures warning.