辫状河致密砂岩储层构型单元定量表征方法

Quantitative Characterization of Reservoir Architecture Units of Braided River Tight Sandstone Reservoirs

针对现有辫状河储层构型单元定量表征方法关键参数获取困难且可靠性存疑的问题,以储层构型理论为指导,基于现代辫状河沉积、钻井岩心、录井和测井等资料,提出了基于单一辫状河道宽度的构型单元定量表征方法。首先,根据单井构型单元解释结果,确定同期辫状河道平面分布;其次,根据连井对比剖面,确定连井剖面内单一辫状河道间的界线位置;再次,根据现代辫状河单一辫状河道宽度与构型单元关系定量模型,限定辫状水道宽度、复合心滩长度及宽度等4级构型单元规模;最后,在单一辫状河道内确定4级构型单元平面分布,进而在密集井网区对复合心滩进行解剖,确定单个心滩位置和几何形态。采用该方法对苏××提高采收率试验区盒8下1-3单层辫状河致密砂岩气藏进行了分析,结果表明:该单层砂岩气藏发育5条单一辫状河道,其宽度为1 050~1 890m;辫状水道宽度为234~435m;复合心滩长度和宽度分别为1 931~3 569m、685~1 242m;单个心滩长度和宽度分别为660~1 880m、310~1 030m。

Aiming at the difficulty in obtaining the key parameters and the doubtful reliability of the existing quantitative characterization method for braided river reservoir architecture units,based on the theory of reservoir architecture on single braided channel width,a new method is proposed.Firstly,based on the analysis of single well reservoir architecture units,the horizontal distribution of coeval braided river channels is determined.Secondly,the single braided river channels are set up,and their width can be measured through connecting-well profiles perpendicular to the paleo-current direction.Thirdly,according to the new quantitative model,the width of braided water channel and the length and width of a complex channel bar are calculated.Lastly,in a single braided channel,the plane distribution of four-stage configuration units is determined,and then the compound channel bar is dissected in the dense well network area to determine the location and geometry of the single channel bar.The new method is applied to evaluate the scale of the reservoir architecture units of the braided river tight sandstone gas field of the 1 3 layer of the lower part of 8th member of the Xiashihezi Formation in the Su××EOR test area.It is shown that five single braided river channels are developed in the 1 3 layer of the 8th member within the width of 1 050 m 1 890 m,a braided channel width of 234 m to 435 m;the length and width of a compound channel bar are 1 931 3 569 m and 685 1 242 m respectively,while those of a single channel bars are 660 1 880 m and 310 1 030 m respectively.