Abstract:

Based on thermodynamic calculation, the thermodynamic features of laumontite dissolution in different fluid are disscussed. The result indicates that: ①Gibbs free energy increment （ΔG） of the reactions involved laumontite dissolution is minus, so laumontite dissolution are all spontaneous reactions in diagenesis environment; ②Gibbs free energy increment （ΔG） of the reactions involved laumontite dissolution is plus relativity with burial depth, and the trend of laumontite dissolution in deeper burial depth is less than that in lower burial or the earth’s surface;③Laumontite dissolves easily and forms secondary pore in diagenesis environment of higher P CO₂ , lower pH, decrease of Ca ²⁺ and increase of K ⁺ ; ④The reactions involved laumontite dissolution are accompanied by the decrease in the volume of the solids, the decrease in the volume of the solids in the reaction Lm- Ill is the most, and it consumes  K ⁺ and conquers dynamics balk of K-feldspar dissolution and makes more K-feldspar dissolution to form secondary pore. So the way which laumontite dissolve to form illite and quartz is most profitable to form reservoir.

Key words: lowresistivity characteristics, grain grade, highlymineralized formation brines, high bound water saturation, Anyue-Hechuan area