Application of Gravel Roundness Quantitative Description in Conglomerates Reservoirs

Abstract

In this paper, we focus on the quantitative roundness characteristics of drilling cores in conglomerates reservoir from the Triassic Baikouquan Formation in the Circum–Mahu Sag, northern Junggar Basin, Xinjiang Province in Northwestern China. Based on de–flat roundness measuring method, we try to use quantitative roundness analysis to distinguish different sedimentary microfacies of core images. As a result, two types of channels deposits gathering coarse-grained sediments are exampled. It reveals that ephemeral channels get a higher roundness value by 0.436–0.811, dominated by sub-rounded shape. Intermittent channels get a smaller roundness value by 0.387–0.678. Meanwhile, roundness variation of gravel in intermittent channel is lower than that of ephemeral channel. There’s good gravel roundness and diversified roundness type in the braided channel deposition developed in fan delta plain. The reason of worse roundness in intermittent channels might be the mix of hard-to-wear source rock gravels after in-lake.