含煤地层下薄砂体分布预测方法:以东海西湖凹陷PB地区为例  

Prediction method of thin sand reservoir with coal bearing:An example from PB area of Xihu Sag at East China Sea

作　　者：罗盼 李九生 LUO Pan;LI Jiusheng(Sinopec Geophysical Research Institute Co.Ltd.,Nanjing 210013,China)

机构地区：[1]中国石油化工股份有限公司石油物探技术研究院,南京210013

出　　处：《地质科技通报》2024年第6期258-270,共13页Bulletin of Geological Science and Technology

摘　　要：在河流-潮汐双向水流控制的沉积环境之下,西湖凹陷PB地区平湖组含油气地层中普遍发育薄煤层,煤层导致储层的地震振幅、相位、频率均会发生一定变化。为明确PB地区煤层的发育对储层识别的具体影响以及储层识别的有效手段,以地震、测井资料为研究基础,在开展储层叠前、叠后地震响应特征的基础上,基于去煤层反射系数地震响应特征分析和基于波动方程的叠后地震正演,在厘清煤层发育对储层特征影响的前提下,采用岩石物理多参数交会分析,以探索研究区储层岩性识别的敏感参数、定门槛值。结果表明,当储层厚度均小于调谐厚度时,对地震数据进行90°相位旋转,煤层对储层影响能一定程度地减弱。针对研究区含薄煤层的薄储层,采用宽频谱反演-叠前Vp/Vs-叠前AVO三步走逐级优质储层预测流程,能较好地刻画研究区含气砂体展布范围。In the sedimentary environment shaped by river-tidal bidirectional flow,thin coal seams are typically lo-cated within the oil-and gas-bearing strata of the Pinghu Formation in the PB area of the Xihu Sag.These coal seams significantly influence the seismic amplitude,phase,and frequency of the reservoirs.[Objective]To bet-terclarify the specific impact of coal seam development in the PB area on reservoir identification and effective identi-fication techniques,[Methods]this paper focuses on analyzing seismic and logging data to evaluate the prestack and poststack seismic response characteristics of the reservoirs.We then investigate the seismic response character-istics of the reflection coefficient after the coal seam is removed and perform poststack seismic forward modeling based on the wave equation.This analysis elucidates the influence of coal seams on seismic responses.Finally,rock physics multiparameter intersection analysis is employed to identify the sensitive parameters and establish the threshold values for reservoir lithology identification within the study area.[Results]When the reservoir thickness is less than the tuning thickness,the seismic data can be rotated by 90°,which reduces the impact of the coal seam on the reservoir diminishes.[Conclusion]For thin reservoirs with associated thin coal seams in the study area,we adopt a three-step high-quality reservoir prediction process that involves broadband spectrum inversion,specifically prestack Vp/Vs and prestack AVOG.This approach allows amore effective description of the distribution range of a-erated sand bodies in the study area.

关 键 词：PB地区 含煤薄储层 地震响应特征 储层预测 薄砂体分布 东海西湖凹陷 

分 类 号：P618.13[天文地球—矿床学]