应用反演技术研究BZ26—2油气田馆陶组沉积特征

A SEDIMENTOLOGICAL STUDY BY SEISMIC INVERSION FORGUANTAO FORMATION IN BOZHONG 26-2 FIELD,BOHAI BAY BASIN

利用层序之间的关系,为基于地震道反演提供初始地质模型,而基于地震道反演的稀疏脉冲反演又为高分辨率层序地层分析提供了依据.在层序划分及反演数据体的基础上,利用油藏分析技术及可视化手段,对BZ26-2油气田馆陶组7个油组主要含油砂体进行了分析.主要认识有:(1)馆陶组可划分为4个旋回,旋回1为辫状河沉积旋回,旋回2为曲流河沉积旋回,旋回3为曲流河沉积夹辫状河沉积旋回,旋回4为辫状河沉积夹曲流河沉积旋回;整体上反映了馆陶期河流沉积时,容纳空间逐渐增大、其所临湖泊扩大的湖进过程.(2)将原馆Ⅳ油组新划分为2个油组,即馆Ⅳ和馆Ⅴ油组,它们具有不同的油水界面(分别为-2279.8m、-2283m).(3)馆Ⅴ油组顶部泥岩为泛滥平原沉积,该套泥岩在油区南部由于河道多次切割而分布范围有限,但在BZ26-2-1和BZ26-2-3井区分布较稳定,可作为局部盖层.馆Ⅳ和馆Ⅴ油组不连通.(4)主力油组馆Ⅳ油组含油砂体为本区最初的曲流河沉积砂体,分布较广但厚度变化较大;而馆Ⅰ油组含油砂体为辫状河沉积砂体,分布广且厚度稳定.

Based on sequence stratigraphy and seismic inversion data volume,the main oil bearing sandbodies of 7 pays in Guantao Formation are analysed using reservoir delineation and visualization methods,resulting in the following conclusions:(1) In BZ26 2 field,Guantao Formation can be divided into 4 cycles (braided stream cycle,meander cycle,meander plus braided stream cycle and braided stream plus meander cycle),reflecting a progressive process of lacustrine expansion and accommodation increasing during sedimentation of the Formation.(2) The original pay Ⅳ can be divided into two pays,i.e.pay Ⅳ and Ⅴ,which have different oil water contacts (-2279.8m and -2283m respectively). (3) The top mudstone of pay Ⅴ,as a set of flood plain deposit,is limited in spreading in the southern field due to multiple cutting by channels,but is quite stable in BZ26 2 1 and BZ26 2 3 well areas and may serve as a local seal.As a result,pay Ⅳ do not communicate with pay Ⅴ. (4) As the main pays,the meander sandbodies in pay Ⅳ spread more widely but change more greatly in thickness,and the braided sandbodies in pay Ⅴ spread widely and is stable in thickness.