莺歌海盆地乐东区中新统黄流组和梅山组是南海北部海域天然气勘探重点层系,复杂的地质条件和普遍存在的高温超压背景,使得储层物性的下限难以界定.根据测井、压汞、地层测试、物性分析等地质资料,合理采用分布函数曲线法、测试法、排驱压力法和经验统计法,明确了有效储层的物性下限,并进一步分析有效储层发育控制因素,优选主要参数对储层进行精细分类.结果表明:①乐东区中新统有效储层孔隙度下限为8，,渗透率下限为0.2×10-3μm2,②乐东区储层物性区域上主要受压实作用的控制,碳酸盐胶结与深部热流体有关的溶解作用是有效储层主控因素,沉积作用控制的储集岩粒度与分选性对乐东区储层物性的影响相对较小,③可将乐东区中新统储层精细划分为Ⅰ、Ⅱ1、Ⅱ2、Ⅲ、Ⅳ1、Ⅳ2共6类,其中Ⅰ、Ⅱ1、Ⅱ2和Ⅲ类为有效储层,Ⅳ1、Ⅳ2类为非有效储层.

Yinggehai Basin is an important Cenozoic gas-rich basin on the northern continental shelf of the South China Sea. With the continuous improvement of oil and gas exploration, the exploration targets have been continuously expanded to the middle and deep layers, and good exploration discoveries have been obtained. The Miocene Huangliu and Meishan Formation of Ledong area of Yinggehai Basin are the key strata for gas exploration in the northern South China Sea. Due to the complex geological conditions, difficult exploration conditions and high temperature and overpressure background in Ledong area, it is difficult to define the lower limit of reservoir physical properties, which affects the reasonable classification of reservoirs. Based on the observation and analysis of petrographic thin sections of 188 samples from more than 10 wells in study area, combining the data of logging, mercury injection, formation test and physical property analysis, and reasonably adopting the distribution function curve method, test method, displacement pressure method and empirical statistical method, the lower limit of effective reservoir physical properties of Miocene Huangliu Formation and Meishan Formation in Ledong area is determined. The controlling factors on effective reservoir development were studied, and the main parameters were optimized to finely classify the reservoir. It provides a scientific basis for the exploration of key fields in Ledong area. The results show that：(1) The lower limit of porosity and permeability are 8， and 0.2×10-3μm2 respectively. (2) The physical properties of reservoir in Ledong area are mainly controlled by compaction. Carbonate cementation and dissolution related to deep thermal fluid are the main controlling factors of effective reservoir, otherwise the grain size and sorting of reservoirs controlled by sedimentation have relatively little impact on reservoir physical properties in Ledong area. (3) The Miocene reservoirs in Ledong area can be finely divided into six types: Ⅰ, Ⅰ1, Ⅱ2, Ⅲ, Ⅳ1 and Ⅳ2，of which Ⅰ, Ⅰ1, Ⅱ2 and Ⅲ are effective reservoirs, and Ⅳ1 and Ⅳ2 are ineffective reservoirs.