缅甸D区块始新统绿泥石特征及成岩演化

CHARACTERISTICS AND DIAGENETIC EVOLUTION OF CHLORITE OF EOCENE IN MYANMAR D BLOCK

在对缅甸D区块碎屑岩成岩作用研究过程中发现,缅甸D区块始新统地层砂岩中自生绿泥石常见,且形态多异,赋存特征也不尽相同。本文先通过对D区块地面8条剖面和两口井下样品进行常规薄片鉴定分析,其后利用X衍射、电镜扫描和探针等手段综合分析研究了本区绿泥石形成、成因与成岩演化过程、展布特征及其对储层的影响。认为本区入海三角洲前缘、滨岸环境是环边绿泥石发育的良好背景,也是高负孔隙度砂岩的一个良好标志;绿泥石成岩过程分为两个阶段,早期绿泥石以环边绿泥石沉淀为主,少量蚀变而成,晚于或稍早于机械压实作用,晚期以蚀变为主,最早发生于杆沸石之后,最晚形成于长石溶蚀之后,伊利石层形成之前;绿泥石环边对石英加大的抑制机理是通过限制石英加大的生长空间和阻碍石英加大的生长方向来实现的,绿泥石环边对于储层孔隙的保存还应考虑绿泥石环边形成之后沸石、方解石沉淀的影响。

Research of diagenesis of clastic rocks in the D block of Burma reveals that the authigenetic chlorites are well developed in Eocene sandstone with different morphology and occurrence.Samples from 8 cross sections and 3 drilling wells are observed by microscope and X-ray,SEM,EMP are used to study the formation,genesis,evolution of diagenesis,distribution characters and their effects on the reservoir.It is showed that the environments of marine delta front and onshore are favorable for the formation of chlorite.They diagenesis process of chlorite can be divided into 2 stages.The early stage is characterized by the formation of precipitation of rim chlorite,initiated after the formation of thomsonite,ended after the corrosion of feldspar and prior to the formation of illite.The rims of chlorite restrain both the enlargement and the growth direction of quartz.The effect of precipitation of zeolite and calcite on the protection of chlorite rims for the porosity of reservoir should be considered.