地震多属性在少井区和无井区沉积体系分析中的应用——以渤中西环BZ3-1区块沙河街组为例

钻井和地震资料的丰富程度决定了储层预测研究精度。在多井区,利用地震属性及单井沉积相来确定平面沉积相,研究精度高;而在少井、无井区的海域,如何利用地震资料进行沉积储层研究,至今没有一个成熟的方法。渤海湾盆地渤中凹陷西环BZ3-1区钻井较少,完整钻遇到沙河街组的井则更少,以该区的沙河街组为例,基于地震多属性分析技术,结合古地貌分析,半定量确定研究区的沉积体系分布特征。通过三维可视化技术和切片技术的高精度三维沉积体系分析表明,由于三级层序发育于二级层序的不同体系域,会导致三级层序的体系域沉积体发育特征的不同。沙三段SQsl3层序发育于二级层序的低位体系域(LST),其低位体系域的扇体规模要远远大于高位体系域(HST)的扇体;SQs3m层序发育于二级层序的水进体系域(HST),其低位体系域三角洲朵体规模与高位体系域的三角洲朵体相当;SQs3u层序发育于二级层序的高位体系域,其高位体系域三角洲朵体规模远远大于低位体系域的三角洲朵体。

SEDIMENTARY SYSTEM ANALYSIS USING SEISMIC MULTI-ATTRIBUTES TECHNIQUE IN AREAS LACKING WELL DATA: AN EXAMPLE FROM SHAHEJIE FORMATION IN BZ3-1 BLOCK OF WESTERN SLOPE OF BOZHONG SAG

The multi-attributes technique has been widely adopted to sedimentary facies analysis recently.The accuracy and resolution of the method depend upon the availability of drilling holes in the area.In the area with enough drilling wells,it is of efficiency and precise enough to use the method of multiple attributes and single-well facies analysis to map the plane distribution of sedimentary facies.However,in the areas with few wells or even no well,the method to optimize seismic attributes and define sedimentary facies remain immature up to date.The well drilling degree is quite low in the BZ3-1 block of the western slope of the Bozhong sag,and few wells have penetrated the Shahejie Formation.In this paper,taking the Shahejie Formation as an example,we studied the distribution pattern of sedimentary systems semi-quantitatively on the basis of seismic multi-attribute analysis,in combination with available palaeogeomorphologic data.Through the study of high-accuracy 3d sedimentary system using the three-dimensional visualization and dissection technique,we discovered that the development of 3rd-order system tracts deposits depended upon their development stage in the 2nd-order sequence.The sequence of SQsl3 of the lower member of Es3 developed in the LST of the 2nd-order sequence,and the size of fans are larger than those formed in the HST;the sequence of SQsm3 of the middle member of Es3 developed in the TST of the 2nd-order sequence,so the size of LST fans are equal to HST fans;the sequence of SQsu3 of the upper member of Es3 developed in the HST of the 2nd-order sequence,and the size of HST delta fans are much larger than those in the LST.