摘要
CFP成像技术是一种理论特性优良的成像技术,不涉及地下速度场修改,更新的仅是聚焦算子。其偏移过程由一个算子驱动,叠前偏移的实现由两个连续的相互独立的聚焦步骤来完成。CFP成像技术的基础是时差,其关键是时移的拾取和聚焦算子的更新。初始模型的选取往往会对时移的拾取和聚焦算子的更新产生影响,因此需对初始模型的建立原则和初始模型对聚焦算子更新的影响进行研究。为此对起伏地形水平界面三层理论模型进行了不同初始模型和特征点的DTS模板及算子更新过程的数值模拟。结果表明,聚焦点相应层位在DTS模板和CFP道集中的位置和同相轴斜率随初始模型的改变而改变,且模型t0 时间的改变比速度的改变敏感;模型速度的增加与模型时间的减小对DTS模板和聚焦算子更新的影响具有类似规律和特征;初始模型的改变不仅影响在DTS模板上对应层位时移的正确拾取,而且将引起在DTS模板上拾取时移时出现串层现象。聚焦算子的更新主要体现在第一次更新上。
CFP imaging technique is an imaging technique having excellent theoretical characters,which is not concerned in modification of velocity field and only the focus operator is renewed.The migration process is driven by one operator,and fulfillment of prestack migration is finished by two continuous focus steps that are independent each other.The basis of CFP imaging technique is moveout,and the keys are pickup of time-shift and renew of focus operator.The selection of the preliminary model tends to have influence on pickup of time-shift and renew of focus operator,so that needs to study the preliminary-model-building principle and influence of preliminary model on renewing focus operator.For that reason,the numeric modeling of DTS templates and operator-renewing processes having different preliminary models and characteristic points is carried out for three-horizontal-layered model with uneven terrain.The results show that the positions of focus-points-related horizons being in templates and on CMP gathers and slopes of events change with preliminary models,and the change of t 0 time of model is more sensitive than the change of the velocity;the influence of the increase of model velocity and the decrease of model time on DTS template and renewing focus operator has similar rule and feature;the variation of preliminary model not only affects the correct pickup of time shifts of corresponding horizons in DTS templates,but also leads to horizon skip when picking up time shifts in DTS template.The renewing of focus operator mainly depends on the first renewing.
出处
《石油地球物理勘探》
EI
CSCD
北大核心
2005年第2期143-148,157,共7页
Oil Geophysical Prospecting
基金
湖北省自然科学基金项目 (2 0 0 1ABB0 0 3)
国家自然科学基金项目 (4 0 1340 34)资助
