摘要
岩石物理联合反演是一种电阻率测值与速度数据的联合反演方法,用来估算深水环境中聚集的天然气水合物。其以Bayesian方法为基础,运用岩石物理弹性理论和经验公式,通过随机模拟计算出反演中涉及到的石油物理参数的自然变化。在墨西哥湾近海底地层中发现的天然气水合物由于仅限于对该区的储层进行测井和岩心取样,所以对其描述的数据很少,并且在含天然气水合物稳定区域采集到的数据仅限于伽马曲线和电阻率曲线,同时近海底地层的地质信息也较少。在估算深水环境中天然气水合物集中度时,由于现有资料的制约必须将涉及到与预测结果相关的不确定性考虑进去,所用的方法不仅可以对电阻率和地震速度模拟反演出的水合物加以计算,而且也为检测与预测结果相关的不确定性提供了一种方法。通过将电阻率与地震速度相结合,可以较好地确定沉积层中水合物的集中度和分布情况,降低预测结果中的不确定性。本文用GOM实例对该方法加以证明。
引文
[1]Archie,G.E..The electric resistivity log as an aid in determining some reservoir characteristics.Transactions of AIME,1942,46:54
[2]Bayes,T..An essay towards solving a problem in the doctrine of chances.Philosophical Transactions of the Royal Society,1783,53:370~418
[3]Collett,T.S..A review of well-log analysis techniques used to as-sess gas-hydrate-bearing reservoirs:in Natural gas hydrates:Oc-currence,distribution,and detection.American Geophysical U-nion,Geophysical Monograph,2001:124,189~210
[4]Helgerud,M.B.,J.Dvorkin,A.Nur,A.Sakai,et al,Elastic-wave velocity in marine sediments with gas hydrates:Effective medium modeling.Geophysical Research Letters,1999,26:2021,2024
[5]Mavko G.,T.Mukerji,and J.Dvorkin.The rock physics hand-book.Cambridge University,1998
[6]Sava,D.C.,and B.A.Hardage.Rock physics characterization of hydrate-bearing deepwater sediments.The Leading Edge,2006,25:616~619