基于地震AVO属性的煤层气富集区预测

Prediction of coalbed methane enrichment zones based on AVO attributes

为了判定AVO技术是否能够用于对煤层气的预测,研究了煤储层含气性与地震AVO属性之间的关系,获得煤储层参数与地震波弹性参数之间的关系式及其AVO响应特征,发现煤储层的含气量随纵波速度、横波速度、密度的增大而减小。对鄂尔多斯盆地大宁—吉县地区5#煤层进行了AVO数值模拟,并预测出其煤层气的相对富集区。AVO数值模拟结果表明,高产井所在的煤储层一般有较强的AVO异常。结论认为:利用AVO属性能够对煤层气的富集区进行预测并为煤层气井位的部署提供依据。

In order to identify if the AVO technology can be also used for the prediction of coalbed methane gas,this paper studies the relationship between gas potential of coal beds and its AVO attributes.A relational expression between coal reservoir parameters and seismic wave elasticity parameters is established and their AVO responses are defined.It is discovered that the gas content of coal reservoirs is decreasing with the increase of P-and S-wave velocities as well as density.The AVO numerical simulation is performed on the coal bed 5# in the Daning-Jixian area of the Ordos Basin to predict the relative CBM enrichment zones.The simulation results show that the coal reservoirs with high-yielding wells generally show relatively strong AVO abnormal phenomena.Field application shows that AVO attributes can be used to predict CBM enrichment zones,thus providing a robust basis for CBM well emplacement.