白云凹陷中深层古近系砂岩储层特征及溶蚀作用对优质储层的控制作用

为明确南海珠江口盆地白云凹陷中深层储层特征及溶蚀作用对优质储层的控制作用,基于岩心观察、铸体薄片、场发射扫描电镜等观察结果,结合X-射线衍射、压汞分析等资料和技术手段,对白云凹陷古近系砂岩储层岩石学特征、储集空间特征和物性特征进行描述,并对影响储层物性、储集性的相关成岩作用进行深入研究。结果表明:白云东洼的储层砂岩类型主要为长石质石英砂岩和岩屑质石英砂岩;白云北坡岩性较东洼复杂,主要以长石质石英砂岩为主,含少量长石岩屑质石英砂岩;白云东洼中深层储层孔隙类型由粒间溶孔、粒内溶孔组成,白云北坡储层孔隙发育程度较白云东洼略高,粒间溶孔、粒内溶孔以及铸模孔含量较高;白云凹陷储层总体呈现低孔低渗特征,有机酸与长石和火成岩岩屑相互作用形成的溶蚀孔隙是控制研究区古近系砂岩储层物性的最主要因素。研究结果对珠江口盆地白云凹陷砂岩储层的勘探开发具有一定借鉴指导作用。

Characteristics of Mid-Deep Paleogene Sandstone Reservoirs in Baiyun Sag and Controlling Effect of Dissolution on High-Quality Reservoirs

To definite the characteristics of mid-deep paleogene sandstone reservoirs and the controlling effect of dissolution on high-quality reservoirs in Baiyun Sag, Pearl River Mouth Basin, South China Sea, according to the core observation, casting slice, field emission scanning electron microscopy and observation results, the lithological characteristics, reservoir space characteristics and physical characteristics of Paleogene sandstone reservoirs in Baiyun Sag were described in combination with X-ray diffraction, mercury penetration analysis and other data and technical means. In addition, a deep study was conducted on the diagenesis related to reservoir physical properties and reservoir quality. As found in the results, the reservoir sandstones in the East Sub-sag of Baiyun Sag are mainly composed of feldspathic quartz sandstone and lithic quartz sandstone. The lithology of the North Slope of Baiyun Sag is more complex than that of the East Sub-sag, primarily composed of feldspathic quartz sandstone, with a small amount of feldspathic lithic quartz sandstone. The pores of the mid-deep reservoirs in the East Sub-sag include intergranular and intragranular dissolved pores. The pore development degree of reservoirs in the North Slope is slightly higher than that of the East Sub-sag, with a higher content of intergranular dissolved pores, intragranular dissolved pores and mold pores. The reservoirs in Baiyun Sag are generally characterized by low porosity and permeability. The dissolved pore formed by the interaction of organic acids with feldspar and igneous rock debris is the most important factor that controls the physical properties of the Paleozoic sandstone reservoir in the study area. The study results can become certain reference and guidance for the exploration and development of sandstone reservoirs in Baiyun Sag, Pearl River Mouth Basin.