四川盆地川中地区震旦系灯影组台地边缘相带地震识别及其分段特征

Seismic recognition and zonation of the platform margin facies of the Sinian Dengying Formation in central Sichuan Basin

四川盆地绵竹-长宁裂陷东、西两侧发育震旦系灯影组台地边缘相带,是重要的油气富集区。运用地震精细解释及层拉平等技术对台地边缘相带开展地震识别、精细刻画及分布研究。台地边缘相带地震反射特征为"丘状"反射或括弧状外形、内部为杂乱或蚯蚓状反射、中弱振幅、中低频率。绵竹-长宁裂陷东、西两侧震旦系灯影组发育灯一期、灯二期及灯四期3期台地边缘相带,其中灯二期发育两个级别台地边缘相带。灯一期台地边缘相带分布在安岳-乐至东侧地区,近南北向展布;灯二期台地边缘相带呈半环状展布;裂陷东侧灯四期台地边缘相带在安岳以南为近南北向,在遂宁-射洪地区为北东南西方向。四川盆地川中地区震旦系灯影组台地边缘相带分布指示出震旦系灯影组有利勘探区带,对勘探具有一定的指导意义。

The Sinian Dengying Formation platform margin facies is developed in east and west of the Mianzhu-Changning Rift,Sichuan Basin,where oil and gas accumulated. Seismic recognition,fine characterization and distribution features of the platform facies zones are carried out by means of detailed interpretation of seismic facies and horizon flattening. Seismic reflection features of facies zones on the platform margin are "dome-shaped"or brackish-shaped,with internal messy or earthworm-like reflections,moderate to weak amplitudes,and low to intermediate frequencies. Three stages of platform margin zones,Z_2dn^1,Z_2dn^2 and Z_2dn^4,developed in east and west of the Mianzhu-Changning Rift,and two stages of platform margin zones developed in Z_2dn^2. The Z_2dn^1 platform margin zone is distributed in eastern area of the Anyue-Lezhi,trending in near North-South direction. The Z_2dn^2 platform margin zone is distributed in a semi-circle shape. The Z_2dn^4 platform margin zone trends in near north-south direction to the south of the Anyue,and in northeast-southwest direction in the Suining-Shehong area. The distribution pattern of the platform margin facies of the Sinian Dengying Formation in the central Sichuan Basin indicates that the Sinian Dengying Formation has favorable exploration zones. This characterization work gives some guidance for further oil and gas exploration.