A New Technique for the Identification of Gas Chimney and Its Application in Basin A

Gas chimney is a special associated structure produced by the activity of thermal fluid in the strata.The occurrence of gas chimney decides the migration of hydrocarbon and the accumulation mode as it acts as migration passageway of oil,gas and water or as the connection of source rock with the traps in the overlying stata.Many studies have been performed by petroleum geologists and geophysicists from the formation condition,controlling factor,mode and seismic reflection characteristics.This paper focuses on the introduction of OpendTec,a new technique for the identification of gas chimney,which is based on the control of dip/azimuth steering,and its application in Basin A.In the process of identification,the steering data containing dip/azimuth information are firstly generated on the seismic data of time domain or depth domain by different dip/azimuth scanning techniques.And then,pick up the seed points,optimize and rank the large amounts of seismic attributes by the neutral network computing with the control of seed points.Finally,the optimum seismic attributes that reflect the characteristics of gas chimney can be obtained and are used to predict the probability of occurrence for gas chimney.This technique supplements the application of pattern recognition technology in the seismic exploration field.The application of this technique in Basin A indicates that there are obvious chimney effects on the top of the target traps,which means the study objects have large probability of oil-gas-bearing,with the potential of exploration.