珠江口盆地深水区白云凹陷储层孔隙特征及影响因素

利用岩石薄片、铸体薄片、荧光薄片、X射线衍射、扫描电镜和压汞分析等手段,对珠江口盆地深水区白云凹陷储层孔隙特征进行了分析,并结合储层的沉积环境、岩性特征和成岩演化过程对影响储层孔隙演化的因素进行了研究。该区储层孔隙类型主要为长石、硅质岩屑和早期碳酸盐胶结物溶蚀、溶解产生的粒间溶蚀孔隙和粒内溶蚀孔隙,在2 750~3 500m和3 800~4 600m深度发育有两个次生孔隙带。沉积相带的分异作用和成岩作用引起的孔喉变化是控制储层物性的主要因素。沉积相带的不同导致储层结构成熟度和成分成熟度的差异,甚至孔隙水的差异,进而导致储层的物性差异。压实作用和碳酸盐胶结作用使得原生孔隙急剧减小,但碳酸盐胶结物又增强了储层的抗压能力,为后期酸性流体溶蚀、溶解提供了空间和物质基础。

Characteristics of pore evolution and its controlling factors of Baiyun Sag in deepwater area of Pearl River Mouth Basin

The thin sections, casting thin sections,fluorescence thin sections, X-ray diffraction, SEM observation and mercury injection measurement methods were used to study the pore characteristics of deepwater reservoir sandstones in Baiyun Sag of Pearl River Mouth Basin and analyze the controlling factors for pore evolution according to the sedimentary environment, lithologic properties and diagenesis evolution. The main pore types in this area are the inter-granular dissolved pore and intra-granular dissolved pore of feldspar, siliceous debris, quartz and carbonate cements. Two secondary pore zones were developed in the depth sections of 2750-3500m and 3800-4600m. The sedimentary facies and diagenesis were the main factors for controlling reservoir properties. The different sedimentary environment resulted in the different texture maturity and composition maturity of reservoir and further resulted in the difference of reservoir properties. Compaction and cementation were the main factors for destroying reservoir properties. Carbonate cements greatly preserved the porosity and provided spaces and matters for the erosion and dissolution of acid fluid in the late diagenesis.