The gas reservoir characteristics and advantageous exploration reas in Middle Triassic Leikoupo Formation-Upper Triassic Ma'antang Formation in Sichuan Basin
Qin Chuan1 Liu Shugen1 Wang Hua2 Sun Wei3 Li Dexing4 Yang Rongjun5 Zhang Changjun1 Wu Xichun1
1.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation|CDUT|Chengdu 610059;2.Exploration and Development Institute of Southwest Oil and Gas Field Co.| PetroChina Chengdu 610051； 3.Chengdu University of Technology|Chengdu 610059； 4.Exploration and Development Research Institute, CNPC Liaohe Petroleum, Panjin, Liaoning 124010|5.PetroChina Research Institute of Petroleum Exploration & DevelopmentNorthwest|Lanzhou 730020
The exploration history of Middle Triassic Leikoupo Formation is about 40 years in Sichuan Basin，but there are only two largeand mediumsized gas pools found till today.Recently，the hydrocarbon shows in Leikoupo Formation were found during drilling and revealed a good exploration prospect for the unit.The reservoir rocks of Middle Triassic gas pools are mainly located in the base(T2l1)and top of the formation(T2l3T2l4)with lowmedium porosity and low permeability，and the hydrocarbon source rocks were Upper Permian Longtan Formation and Upper Triassic Xujiahe Formation，respectively.The component of natural gas in Middle Triassic was varied.The main reservoir spaces are various secondary dissolved pores，and the reservoir type is porous or fracturedporous.The sealing of gas pools is welldeveloped with good direct and indirect cap rocks.The reservoir rocks of Upper Triassic Maantang Formation are calcarenite and micrite located at the base of the unit，and its source rock and seal are similar to the gas pools in the top of Leikoupo Formation(T2l34).The characteristics of the sourcereservoirseal plays of MiddleUpper Triassic in Sichuan Basin are divided into two types： 1)upper Permian Longtan Formation source rock＋the reservoir rocks in the firstsecond segment of Leikoupo Formation(T2l12)＋the anhydritesalt seal in Leikoupo Formation； 2)Upper Triassic source rock＋the reservoir rocks in the thirdfourth segment of Leikoupo Formation(T2l34)and in upper Triassic Maantang Formation＋the mudstone seal in the Upper Triassic.The frontier area of the centralsouthern segment of Longmen Mountain should be the prospect area of the oilgas exploration in the top Leikoupo Formation(T2l34)and Maantang Formatioon in Sichuan Basin.
. The gas reservoir characteristics and advantageous exploration reas in Middle Triassic Leikoupo Formation-Upper Triassic Ma'antang Formation in Sichuan Basin[J]. Chinese Journal of Geology, 2011, 46(01): 258-272.