Improvement and Application of the Methods of Gas Reservoir Cap Sealing Ability

Key words: 
• large and medium

Abstract: Through statistics,it is concluded that the thickness and displacement pressure of cap rock, destroy degree of cap rock from fault, pressure of gas reservoir and gas viscosity are the main factors that influence the gas reservoir cap sealing ability of 46 large and medium gas fields in China. According to relationship between them and sealing and preservative ability of gas reservoirs, this paper has corrected an evaluation method of sealing and preservative ability of gas reservoirs, and evaluated for sealing and preservative ability of large and medium gas fields in China by the method. Finally it is concluded that sealing and preservative ability of 46 large and medium gas fields in China were bad in the main, followed by the middle, again best, and at least were better. Through the study of the sealing and preservative ability of cap rock and gas reserves abundance of 46 large and medium gas fields in China, this paper considered that there was a direct correlation between them. The average reserves abundance of gas fields sealed and perseverated by medium cap rock is the highest, followed by better cap rock. The minimum is best and bad cap rock. It indicates that sealing and preservative ability is not the only main factors controlling formation of large and medium gas fields with high reserve abundance in China. The reserve abundance of large and medium gas fields was yet controlled by other main factors.