The existence of condensate inside of reservoir will change the relative permeability of gas and thus affect the production rate of gas. In special cases, the production rate is also induced by compaction of reservoir rocks. For unconsolidated rocks the compaction tends to make porosity of rocks change and for bigger compressibility of rocks it is possible that repacking of granular of rocks is happened during compaction. Analytic prediction for this special case where compaction and condensate present that will change permeability and relative permeability is not available right now. Prediction is done by using numerical simulator coupled with geo mechanic simulator. An analytical equation is developed using continuum mechanics mass balance theory which is states that mass of particular rock before and after compaction is still same. Analytical equation is compared to numerical simulation to see the agreement between two results.