川东长兴组生物礁分布控制因素及地震识别技术

GEOLOGICAL CONTROL FACTORS OF CHANGXING ORGANIC REEF DISTRIBUTION AND SEISMIC PREDICTION TECHNIQUES,EAST SICHUAN BASIN

四川盆地东部地区龙潭末期形成的"开江—梁平"海槽古地貌与长兴期的持续海侵背景共同控制了该区长兴组生物礁的生长形态及分布规模,而"开江—梁平"海槽东西两侧的台缘相带为生物礁分布的有利相带。通过二维、三维地震剖面,结合长兴组顶部的反射形态和长兴组顶部与底部反射时差等特性,识别出了长兴末期"海槽—前缘斜坡—岩隆—台地"相带,且生物礁主要分布在地震岩隆相带中,认为三维地震资料中的振幅切片和相干体切片技术,可以精细"雕刻"生物礁形态和分布特征。

The organic reef formation and distributed scale are controlled by the ＂Kaijiang-Liangping＂ trough palaeogeomorphology formed at the end of ＂Longtan＂ period and sustained sea transgression during the ＂Changxing＂ period in the eastern part of Sichuan Basin. The platform margin facies on both sides of the ＂Kaijiang-Liangping＂ trough are the favorable regions of organic reef growth. Different facies of ＂trough-foreslope-buildup-platform＂ at the ＂Changxing＂ period are identified using 2D and 3D seismic profiles in combination with the reflected shapes of the stratigraphic top of Changxing Formation and the time difference between top and bottom in the Changxing Formation strata. The organic reefs are mainly distributed in the rock crown of the seismic profiles. The shape of organic reefs and their distribution can be predicted and carved by using techniques of amplitude slice and coherent slice in the 3D seismic profiles. Based on the techniques above, the expected results have been achieved in the gas fields of Wubaiti and Gaofengchang.