中文摘要：

对琼东南盆地陵水组二段泥岩盖层进行宏观研究,认为盖层岩性以浅海相泥岩为主,侧向连续性好,单层厚度大,砂质含量低,但是累积厚度偏小。利用测井声波时差（DT）和实测岩石样本排替压力之间的关系计算陵水组三段砂岩和陵二段泥岩的排替压力差。通过排替压差和可封闭气藏高度公式的计算,认为陵二段泥岩可以封盖下伏陵三段砂岩储层中高1 311-1 552 m的天然气柱。选取岩性、沉积环境、最大单层厚度、累积厚度、含砂量以及储层和盖层排替压差作为参数,分别赋予相应的权重,对泥岩盖层进行综合评价,认为发育于与陵三段储层配套部位的陵二段泥岩其综合品质级别属于Ⅰ—Ⅱ类,盖层综合品质向凹陷方向递增,向凸起方向递减,并且对陵三段发育于隆凹过渡部位的砂岩起到良好的封盖作用。

英文摘要：

By macroscopic evaluation to mudstone caprock in the second member of Lingshui Formation in the Qiongdongnan basin, the caprock is composed of shallow marine mudstone with good lateral continuity, large singleqayer thickness,low sandy content, and relatively small total thickness. We calculated the displacement pressure between mudstone of the second member of Lingshui Formation and sandstone of the third memher of Lingshui Formation based on relationship between sonic travel time and displacement pressure. Based on formula for difference of displacement pressure and sealing ability, the mudstone of the second member of Lingshui Formation can seal the 1 311-1 552m height of gas column in the sandstone of the third member of Lingshui Formation. Selecting parameters （i. e. lithology, sedimentary environment, largest single-layer thickness, total thickness, sand content, displacement pressure difference between reservoir and caprock） ,we comprehensively evaluate the ability of mudstone as caprock. The mudstone in the second member of Lingshui Formation which match to the reservoir of the third member belongs to type Ⅰ-Ⅱ, with sealing quality increases toward depressions and decrease toward the uplifts. The mudstone has a good sealing ability on the third member sand reservoir along the transition belt of the depression and uplift.