动态图像法与镜下测量法粒度分布结果对比研究

动态图像法、镜下测量法在地下沉积岩粒度分析中的应用研究较为薄弱。对塔里木轮南地区X100井三叠系水下分流河道12块砂岩样品分别采用以上两种方法进行粒度测试,将所测得的各组分含量、粒度曲线及粒度参数进行对比分析,并对镜下测量法粒度结果开展校正研究,以使这两种方法在今后能更广泛地运用于粒度分析。研究结果表明:相较于镜下测量法,动态图像法检测粗组分含量偏大而细组分含量偏小,黏土—粉砂组分和中砂组分是两种方法产生差异的分界线。检测颗粒数目的悬殊和岩石类型是两种方法存在差异的主要原因,测试方法的量程、测量原理和颗粒形状也会造成一定的影响。基于岩性的镜下测量法粒度结果校正,使两种方法的细砂—粗砂组分含量、粒径参数的相关系数从0.25~0.80提高到0.88~0.95,达到了校正基本目的,其准确性得到有效的提高。

Comparison of Dynamic Image Analysis and Thin-section Measuring Analysis Grain-size Test Method

Compared with traditional grain-size test methods, research on the application of the dynamic image and thin-section measuring methods in underground sedimentary rock grain-size analysis is currently relatively weak. In this paper, taking 12 sandstone samples from Well X100 in the Lunnan area, Tarim basin and from underwater distributary channels of Triassic, we compared and analyzed the results obtained using the dynamic image and thin-section measuring methods. The content of each grain gradation, grain-size curves, and grain-size parameters are included in the testing results. Then calibration research of the testing results obtained from the thin-section measuring method was carried out. This paper aims to make the two methods more widely applicable to grain-size analysis in the future. The research results show that, compared with results obtained from the thin-section measuring method, the content of coarser sand measured using the dynamic image method is higher and that of finer sand is correspondingly smaller. The clay-to-silt content and medium sand content represent the boundary line which differentiates the two methods. The sharp contrast of detecting particle amount and lithologic characteristics are the main reasons for the difference, upon which the measurement range, measurement principle, and particle shape also exert some influence. The calibration method for the thin-section measuring method proposed here is based on rock type and makes the correlation coefficients (R2) of the testing results (content of fine sand to coarse sand and grain diameters) by the post-calibrated thin-section measuring method with the dynamic image method increase from 0.25-0.80 to 0.88-0.95, achieving the primary purpose of calibration and improving the accuracy of the thin-section measuring method.