莺-琼盆地中新统高温超压储层特征及形成机制

中新统黄流-梅山组重力流、高温超压储层是南海北部莺-琼盆地中央坳陷带主力勘探层系，发育粉、细、中、粗砂岩与中、低、特低渗物性特征.通过研究高温超压储层特征，确定有利储层形成机制，为重点领域评价提供地质依据.结果表明，由东方到乐东区到乐东-陵水凹陷、由凹陷斜坡区到凹陷中心，由于地温梯度与异常超压形成时间、强度的变化，进入各成岩期深度加深，储层孔隙度纵向减小幅度不大，明显不同于斜坡区常压储层.沉积环境控制的储集岩粒度、泥质杂基与高温超压、热流体控制的成岩作用共同控制有利储层，以往凹陷方向发育早期超压保护的海底扇区为有利，凹陷斜坡区热流体作用形成大量次生孔隙，发育中渗“甜点”储层. 

Reservoirs Characteristics and Formation Mechanism of High Temperature and Overpressure Reservoirs from Miocene in Ying-Qiong Basin

The main exploration strata are gravity flow deposits and high temperature and overpressure reservoirs with silty, fine, medium and coarse sandstone, and with physical characteristics of medium, low and ultra-low permeability, from the Miocene Huangliu-Meishan Formation in the central depression of Ying-Qiong Basin in the northern South China Sea. By studying the characteristics of high temperature and overpressure reservoirs, the formation mechanism of favorable reservoir is determined, which provides geological basis for evaluation of key areas. From Dongfang to Ledong to Ledong-Lingshui Depression, from the slope area of the sag to the center of the sag, the depth is deepened in each diagenesis period because of differences in the geothermal gradient and the formation time and development intensity, of abnormal overpressure, however, the porosity decreases slightly in the longitudinal direction, which is obviously different from the atmospheric reservoir in the slope area. Favorable reservoirs are controlled by the grain size and mudstone matrix of reservoir rock controlled by sedimentary environment, and diagenesis controlled by high temperature, overpressure and thermal fluid.The submarine fan reservoir with overpressure protection is favorable in the center of sag. The medium permeability "sweet spot" reservoir is developed with a large number of secondary pores formed by thermal fluids in the slope.