景鹏飞, 胡高伟, 卜庆涛, 陈杰, 万义钊, 毛佩筱. 基于岩石物理模拟与声学实验识别孔隙—裂隙充填型水合物[J]. 海洋地质与第四纪地质, 2020, 40(6): 208-218. DOI: 10.16562/j.cnki.0256-1492.2019122501
引用本文: 景鹏飞, 胡高伟, 卜庆涛, 陈杰, 万义钊, 毛佩筱. 基于岩石物理模拟与声学实验识别孔隙—裂隙充填型水合物[J]. 海洋地质与第四纪地质, 2020, 40(6): 208-218. DOI: 10.16562/j.cnki.0256-1492.2019122501
JING Pengfei, HU Gaowei, BU Qingtao, CHEN Jie, WAN Yizhao, MAO Peixiao. Identification of pore-filling and fracture-filling hydrate by petrophysical simulation and acoustic experiment[J]. Marine Geology & Quaternary Geology, 2020, 40(6): 208-218. DOI: 10.16562/j.cnki.0256-1492.2019122501
Citation: JING Pengfei, HU Gaowei, BU Qingtao, CHEN Jie, WAN Yizhao, MAO Peixiao. Identification of pore-filling and fracture-filling hydrate by petrophysical simulation and acoustic experiment[J]. Marine Geology & Quaternary Geology, 2020, 40(6): 208-218. DOI: 10.16562/j.cnki.0256-1492.2019122501

基于岩石物理模拟与声学实验识别孔隙—裂隙充填型水合物

Identification of pore-filling and fracture-filling hydrate by petrophysical simulation and acoustic experiment

  • 摘要: 孔隙充填和裂隙充填是自然界中水合物赋存的两种基本形态,其类型判别对储量评价、钻井安全以及环境评估均具有重要影响。本文模拟南海孔隙充填和裂隙充填两种类型水合物储层,利用岩石物理模型和声学模拟实验获取声波速度和密度,对两种类型的识别方法进行了探索。结果显示,孔隙充填和裂隙充填型水合物沉积体系的纵波速度都随水合物体积分数的增大而增大,密度都随水合物体积分数增大而减小。将速度与密度参数结合计算两种类型水合物阻抗和\rho \sqrt V _\rmp属性表明:对于含孔隙充填型水合物沉积体系的\rho \sqrt V _\rmp属性,岩石物理模拟的计算结果与实验结果斜率均为正;而对于含裂隙充填型水合物沉积物的\rho \sqrt V _\rmp属性,其斜率均为负。但当水合物体积分数小于40%时,含裂隙充填型水合物沉积物的理论计算结果与实验值存在偏差,因此,在计算低体积分数水合物的\rho \sqrt V _\rmp属性时,需要对模型进行适当修正。本文利用\rho \sqrt V _\rmp属性对GMGS2航次16井赋存的孔隙充填和裂隙充填型水合物进行了验证,结果表明井中上部分赋存的水合物以裂隙充填型为主,底部以孔隙充填型为主,验证结果与实际钻探结果一致,表明该方法用于识别水合物类型是可行的。

     

    Abstract: Pore-filling and fracture-filling are two of the basic occurrences of natural gas hydrates in nature. To discriminate the type of gas hydrate is critically important for resource assessment, drilling safety and environment evaluation. In this paper, simulation experiment was carried out for the pore-filling and fracture-filling hydrate reservoirs in the South China Sea. The acoustic velocity and density of the two kinds of hydrate are obtained by petrophysical simulation and acoustic experiment simulation. The results suggest that the P wave velocity of the depositional mediums containing pore-filling and fracture-filling hydrate tends to increase with the volume fraction of hydrate, while the density decreases. Furthermore, we tested the impedance and the \rho \sqrt V _\rmp property of the two types of hydrate by combining velocity and density parameters together. The results also show that for the pore-filling hydrates, the properties of \rho \sqrt V _\rmp calculated by the petrophysical models and experimental \rho \sqrt V _\rmp both show positive slope, while The \rho \sqrt V _\rmp property of the fracture-filling hydrate shows negative slope. However, the differences between the model and experiment results of fracture-filling hydrate are obvious when the volume fraction of gas hydrate is less than 40%. It means that the petrophysical for fracture-filling hydrate needs to be further improved. In addition, pore-filling and fracture-filling hydrate in GMGS2-16 Site has been verified by the property of \rho \sqrt V _\rmp. The results show that the hydrate in the upper part of the well is mainly fracture-filling hydrate, as the bottom dominated by pore-filling hydrate. The verification has been confirmed by actual drilling results.

     

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