The prime purpose of this book is to present the basic principles of exploration and calculation of reserve natural gas deposit. A short glance is presented on the natural gas deposit in Teku, Kathmandu valley. The survey area covered of 4 Sq.Km. out of the valley's total area of 650 sq.km and 14 wells previously drilled in this area were used, having depth of about 300 m and extending. People are willing to replace their existing source of energy.