南海北部神狐海域天然气水合物成藏特征及主控因素新认识

发布时间：2018-07-26 07:37

【摘要】：南海北部陆坡神狐海域烃源岩生烃潜力巨大且烃类运移条件良好,可为水合物成藏提供充足的气源和通畅的疏导通道,而且神狐海域海底沉积层的温度、压力条件满足水合物形成的要求,具备了水合物聚集成藏的地质条件,成为我国水合物勘探开发的重点靶区。为了明确神狐地区水合物的成藏特征和主控因素,首次将随钻成像测井引入对水合物赋存状态、成藏序列、成藏模式和主控因素的研究中,从而为今后水合物的开采和钻井方案的设计提供强有力的理论依据。通过随钻成像测井、电阻率频谱及相对饱和度分析发现神狐海域共发育厚层状、分散状、斑块状、断层附近和薄层状5种赋存状态的水合物,其中厚层状和分散状水合物相对饱和度高且厚度大,开采价值较大,是研究区的主力水合物层,厚层状水合物常分布于水合物层顶部而分散状水合物常分布于水合物层底部;斑块状、断层附近和薄层状水合物相对饱和度较低且分布不规律,开采价值较小。厚层状、分散状、斑块状和断层附近水合物主要为深部热解气通过断层运移至水合物稳定区聚集成藏,为构造渗漏型水合物;薄层状水合物主要为浅部生物气横向运移聚集至水合物稳定域,为地层扩散型水合物。神狐海域发育开启型、填充型和界面型3种类型的断层,断层作为气体和流体的运移通道,沟通了气源和水合物稳定带,控制了水合物在纵向上和横向上的展布范围,为神狐地区水合物的主控因素。
[Abstract]:The source rocks in the Shenhu sea area on the northern slope of the South China Sea have great hydrocarbon generation potential and good hydrocarbon migration conditions, which can provide sufficient gas sources and unobstructed channels for hydrate accumulation, and the temperature of the bottom sediments in the Shenhu sea area. The pressure conditions meet the requirements of hydrate formation, and have the geological conditions of hydrate accumulation and accumulation, and become the key targets for hydrate exploration and development in China. In order to clarify the reservoir forming characteristics and main controlling factors of hydrate in Shenhu area, it is the first time that the imaging logging while drilling is introduced into the study of the state of hydrate occurrence, the sequence of gas accumulation, the model of reservoir formation and the main controlling factors. It provides a strong theoretical basis for the exploitation of hydrate and the design of drilling scheme in the future. Through imaging logging while drilling, resistivity spectrum and relative saturation analysis, it is found that there are five kinds of hydrates in the Shenhu sea area, which are thick layered, dispersed, plaques, near faults and thin layers. The relative saturation and thickness of thick and dispersed hydrates are high, and the exploitation value is great, which is the main hydrate layer in the study area. The thick layer hydrate is usually distributed at the top of the hydrate layer and the dispersed hydrate is usually distributed at the bottom of the hydrate layer. The relative saturation of patch, fault and thin layer hydrate is low and irregular, and the exploitation value is small. Thick layered, dispersed, patch and near fault hydrates are mainly deep pyrolytic gas migration through faults to hydrate stable region to accumulate and form reservoir, which is structural leakage hydrate; The thin layer hydrate mainly consists of shallow biogas translocation and accumulation to the stable region of hydrate, which is stratigraphic diffusive hydrate. There are three types of faults developed in Shenhu sea area: open type, filling type and interfacial type. As gas and fluid migration channels, faults communicate gas source and hydrate stability zone, and control the distribution range of hydrates in longitudinal and horizontal directions. It is the main controlling factor of hydrates in Shenhu area.
【作者单位】：中国地质调查局广州海洋地质调查局;斯伦贝谢中国地球科学与石油工程研究院;
【基金】：国家高技术研究发展计划“863”项目(2013AA092500) 中国地质调查局项目(DD20160211)
【分类号】：P618.13

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