中扬子上石炭统碳酸盐岩沉积、成岩作用和储层特征

SEDIMENTATION, DIAGENESIS AND RESERVOIR CHARACTERISTICS OF THE UPPER CARBONIFEROUS CARBONATE ROCKS IN THE MIDDLE YANGTZE AREA

关键词:  碳酸盐岩  成岩作用  储集层

Key words:  carbonate rock  diagenesis  reservoir

摘要:

区内上石炭统主要的相、亚相有滨岸相:碳酸盐潮坪亚相;碳酸盐台地相:台地浅滩亚相、开阔台地亚相、局限台地亚相。有利的储集相带为滨岸相中的碳酸盐潮坪亚相和碳酸盐台地相中的台地浅滩亚相,次为开阔台地亚相。影响区内上石炭统碳酸盐岩储屡储集性能的成岩作用有:胶结作用,溶蚀作用,压实、压溶作用,白云化作用,其中白云化作用、埋藏溶蚀作用和压溶作用是形成进油期孔隙最为重要的作用。沥青产状和萤光显示研究表明,区内上石炭统碳酸盐岩的储集空间为:晶间孔、晶间溶孔、基质溶孔、粒间溶孔、缝合状缝隙。储集岩类为:粉一细晶白云岩类、微—亮晶颗粒云(灰)岩类、泥晶灰岩类、蓝藻、有孔虫云岩类。区内上石炭统最佳储集层段为黄龙组下段,次为黄龙组上段。

Abstract:

The petrographic and sedimentological data show that the Carboniferous strata in the Middle Yangtze area are assigned to the littoral facies, carbonate tidal-flat subfaeies, carbonate platform facies, platform-shoal subfacies, open platform subfacies and restricted platform subfacies, among which the carbonate tidal-flat subfacies and platform-shoal subfacies together with the open platform subfacies are believed to be the favourable reservoir facies zones.
The diagenesis influencing the reservoir characteristics of the carbonate reservoirs comprises cementation, erosion, compaction, pressure solution and dolomitization, among which dolomitization, burial erosion and pressure solution are interpreted as the most important processes which are responsible for the formation of the pore spaces created in the oil penetration stage.
The modes of occurrence of bitumen and fluorescence analysis have revealed that the reservoir pore spaces of the Upper Carboniferous carbonate rocks in the study area include intercrystalline pores, intercrystalline solution pores, matrix solution pores, intergranular solution pores and stylolitic fissures. The reservoir rocks are composed of silty-fine crystalline dolostones, micritic-sparry grainstones and dolostones, micritic limestones, blue algae-foraminiferal dolostones, and the best reservoir members consist of the lower and apper members of the Huanglong Formation.