致密砂岩多因子储层精细分级评价方法——以东海盆地西湖凹陷渐新统花港组上段H3砂组为例

东海盆地西湖凹陷西次凹渐新统花港组上段H3砂组为低孔低渗—低孔特低渗致密砂岩储层，优质储层分布成为制约开发产能的关键问题。基于岩心、测井及物性测试等资料，对该区进行了沉积微相刻画和储层物性分析，结合构造、沉积微相发育特征，对储层展开精细分级评价和优质储层预测。研究表明，H3砂组储层分布主要受构造特征、沉积微相、砂体厚度和孔渗条件四个因素影响。在综合分析各因素与含气饱和度关系的基础上，建立了受产能约束的四因子储层精细分级评价标准，把H3砂组储层划分为“甜点”储层（Ⅰ类）、中等储层（Ⅱ类）和无效储层（Ⅲ类）三种类型。优质储层预测研究区H3-3小层为可能的高产能潜力带，H3-1、H3-2和H3-4小层次之。 

Multi-factor evaluation for fine grading of tight sandstone reservoirs: a case study from H3 sand group in the upper section of Oligocene Huagang Formation,Xihu Sag,East China Sea Basin

The H3 sand group of the upper section of the Oligocene Huagang Formation in the western sub-sag of the Xihu Sag of the East China Sea Continental Shelf Basin is a tight sandstone reservoir with low porosity and low or ultra-low permeability. The distribution of high-quality reservoirs has become a key factor restricting productivity. Based on coring, well logging and physical property test data, the sedimentary microfacies and physical properties of the H3 sand group were studied, and a fine grading evaluation and "sweet spot" prediction were carried out. The reservoir distribution in the H3 sand group was mainly affected by four factors:structural characteristics, sedimentary microfacies, sand thickness and conditions of porosity and permeability. Moreover, on the basis of comprehensive analysis of the relationship among these factors and gas saturation, a four-factor reservoir fine grading evaluation method was proposed. The H3 sand group reservoirs were divided into three types:"sweet spot" reservoirs (type Ⅰ), medium reservoirs (type Ⅱ) and ineffective reservoirs (type Ⅲ).The H3-3 single sand layer has a great exploration potential, followed by the H3-1, H3-2 and H3-4 single sand layers.