滨里海M区块深层地震采集参数优化及效果

哈萨克斯坦滨里海盆地M区块油气资源丰富,勘探程度较高。以往的勘探目标主要集中在不超过3000m的浅、中层。超过3000m的深层地震资料存在信噪比低、成像精度低等不足,并存在一定的层间多次波。为改善深层地震资料的成像效果、提高深层地质目标成像精度,首先分析归纳了以往面向浅、中层勘探目标的采集参数造成深层成像精度不高的原因,主要包括排列长度较短、覆盖密度较低、倍频程不高、多次波较为发育等因素;然后根据理论计算和正演模拟结果,针对性地面向深层目标优化了覆盖密度、炮检距长度、扫描频率、多次波压制等采集参数;最后将优化后的采集参数应用于新的三维地震勘探中,结果显示其在深层成像精度、多次波压制等方面均取得了明显的进展,较好地达到了预期效果。

Block M is a key oil-producing block with rich oil and gas resources in the Caspian Basin of Kazakhstan.Previous exploration targets in this block mainly focused on the shallow and middle layers within a depth of 3000 m.Because of the absorption and attenuation and the strong reflection shielding of the overlying gypsum-salt layer,data from the deep layer below 3000 m are characterized by a low signal-to-noise ratio,low imaging accuracy,and multiple inter-layer development.In this study,in order to enhance the imaging of the deep layer,the current situation and characteristics of the previous exploration data of this block and its surrounding areas were analyzed,and the shortcomings in the parameters for deep-seated imaging were summarized.Through theoretical calculations and forward simulation results,acquisition parameters such as the coverage density,offset length,scanning frequency,and multiple wave suppression were optimized for deep targets.The results showed that the imaging accuracy for deep exploration was improved.