Permian Reef Oil ＆ Gas Pool in Southern China Controlled by Relative Sea Level Changes

Key words: 
• relative sea level changes /
• progradational reef /
• aggradational reef /
• offlapping reef

Abstract: According to the relation between relative sea level changes rates and reef growth rates,Permian reef in southern China can be devided into three types:offlapping reef,aggradational reef and progradational reef.When relative sea level rising rate is higher than reef growth rate,offlapping reef configuration was pingroduced.When relative sea level rising rate is equivalent to reef growth rate,aggradational reef configuration was formed.There are three types of progradational reef configuration:1) During relative sea level rising rate is lower than reef growth rate;2) Stillstand of relative sea level;3) relative sea level fall.Permian reef in southern China distributed mainly over Nanpanjiang area and eastern Sichuan to western Hubei area.There are the Maokou Age progradational reef and the Changxing Age aggradational reef in Nanpanjiang area.There are both offlapping reef and progradational reef of the Changxing Age in eastern Sichuan to western Hubei area. There are typical models of diagenetic and oil-gas pool in different types of reef. Firstly, relative sea level changes control on reef heterogeneous reservoir rocks and pore rich accumulation zone. Distribution of the time and space of petroleum in reef were controlled by reef heterogeneity. It is very important to recognize the regular patterns of the time and space of reef pore rich accumulation zone for exploration of the reef oil and gas pool. Secondly,relative sea level changes control on mechanism and configurations of the elements of the reef oil and gas bearing system.Analysis of the reef oil and gas-bearing system could help us preliminarily evaluate the potential of reef oil and gas-bearing system before drilling.Thirdly,different types of the reef complexes have their own contributing factors and regular patterns of the time and space.Through analysis of the contributing factors and regular patterns of the time and space,we might predict buried reef more precisely.