CO2驱油与封存过程中时移地震纹理属性分析——以胜利油田G89区块为例

时移地震是监测CO2强化驱油(CO2-EOR)效果及CO2在地下封存范围的有效手段,但常规地震属性还不能很好地识别油藏注入CO2后储层及流体特征变化.为补充常规地震属性的不足,本文引入基于灰度共生矩阵理论的地震纹理属性分析技术,将其应用在胜利油田G89区CO2-EOR及地质封存的时移三维地震数据中,计算时移地震体的纹理属性,比较、优选、做差,从而识别CO2注入后在地下的运聚通道、运移方向及分布范围.时移三维地震纹理属性对比的关键,在于两次纹理计算参数的选择和结果的一致性处理,本文使用相同的纹理计算参数计算两次地震盖层、储层纹理属性,并采用使两次三维地震资料盖层纹理特征差异最小的方法,得到校正因子,用该校正因子对储层纹理属性进行处理,根据储层校正结果分析CO2的运移和分布.结果表明,经过盖层一致性处理的储层地震纹理属性,背景干扰信息少,断层与背景信息对比度高,主断层刻画更为清晰,分辨率高,明显增强了储层平面特征的可视性,得到了清晰的CO2运聚通道、波及范围及分布情况.注入CO2后,工区内大部分井出现增产或稳产现象,距注入井远距离的生产井产量快速增加,这些特征与属性分析结果相吻合.

Time-lapse seismic texture analysis in CO-EOR and storage:G89 area,Sinopec Shengli oilfield,China

Time-lapse seismic is a valid method to monitor the effect of CO2-EOR and CO2 distribution range underground.However,the results are not good when the conventional seismic attributes are applied to recognize reservoir and fluid characteristics because these attributes have their own limitations,including errors from seismic data acquisition and processing,which will affect their application.In order to complement the deficiencies,more seismic attributes are considered in this paper.The seismic texture analysis based on the gray level co-occurrence matrix is applied to analyze the time-lapse seismic data of CO2-EOR and storage area from SINOPEC Shengli Oilfield China.Seismic texture has dual definitions in stratigraphic and seismic domains and is more indicative of seismic facies.The CO2 migration pathways,directions,and distribution underground have been identified after calculating the texture of the time-lapse seismic volume,comparing,selecting the texture energy from 14 texture attributes and acquiring the difference.The key point of time-lapse seismic texture analysis is the selection of texture computation parameters and the consistency of the result.The same parameters are used to calculate twice seismic texture of caprock and reservoir,and we minimized the caprock texture difference of time-lapse data,acquired a correction factor which also applied to the reservoir and analyzed the CO2 migration and distribution according to the reservoir correction.Case studies indicate that reservoir texture after calibration has less interference information than the background,higher contrast between the main faults and background,higher resolution,the visuality of reservoir characteristics has been enhanced obviously,and CO2 migration pathways,swept range and distribution are more clearly.The main faults of the reservoir,the migration pathways and distribution of CO2 are clearly displayed which is better to explain the increased or stable production of oil wells in the study area,especially the rapid increase in production wells far away from CO2 injection wells.