【摘要】 压力是天然气水合物资源量评价的重要参数.常规基于速度分析的压力预测方法过多依赖于经验公式,精度较低、地质意义不明确,难以满足资源量评价的需求.为了获取更可靠的含水合物沉积层压力分布及演化特征信息,本研究采用基于地质模型的流体压力模拟方法对区域压力场进行研究.基于沉积压实模型的流体压力模拟方法由于将地质信息与地震数据有机结合起来,因而不但能够获取现今压力场的状态,而且能够对压力场的演化特征进行分析.通过结合南海1148站位资料,模拟得到了研究区浅层的孔隙度、超压及流体压力数据,通过与实际数据对比,进行误差分析,获取的模拟数据与实际数据误差较小,验证了该方法的准确性和有效性.模拟结果表明,沉积速率和渗透系数对模拟结果影响较大,沉积速率增加,孔隙度增加,超压增加,有效应力减小,渗透系数增加,孔隙度降低,超压降低,有效应力增加,计算误差很可能是二者共同引起的.该方法可以为现有的水合物资源评价技术体系提供有力支撑.更多还原

【Abstract】 Considering that gas hydrate formation is an extremely complex dynamic,the conventional resources evaluation model of volumetric method has been difficult to meet the needs of hydrate exploration.Pressure is one of the most important parameters for natural gas hydrate resource evaluation,which will help us getting the stress evolution characteristics in the hydrate accumulation area.Previous pressure prediction methods mostly rely on the empirical formula using the velocity information.The estimates had lower forecast precision and ambiguous geological meaning of parameters,which were unsuitable to reservoir predict.Forward modeling of compaction-driven pressure evolution can not only analyze the current tectonic stress field,but model the geologic evolution process with the organic combination of geological and geophysical study.Combining the seismic data and logging from ODP1148 site,a mathematical model based on compaction theory is established and the relationship between the velocity and porosity,density and effective stress is build.By compared with the real data,the errors are analyzed and compared.Simulating results show that the sedimentation rate and the permeability coefficient have great influence on pressure field.Adding sedimentation rate will get larger porosity,more overpressure and major fluid pressure,moreover,increasing permeability coefficient will get smaller porosity,lesser overpressure and minor fluid pressure.The errors between model data and real data are small.The errors may be caused by both parameters.Our study show that the forward modeling method of compaction-driven pressure evolution can be a component of hydrate resource evaluation technology system.更多还原