关键词: 海相碳酸盐岩台地, 沉积旋回, 含钾层段, 测井响应, 三叠系, 川中地区

Abstract: To identify favorable salt-and potash-forming layer, we mainly rely on logging interpretation and coring verification. The continuously carbonate platform shows cyclical growing and recorded valuable information about the facies transition of carbonate rocks, which was synchronized with the relative sea-level cycles. This paper presents a method to preliminarily judge favorable potassium-rich intervals. By using natural gamma ray logging data and numerical simulation, high-frequency sedimentary cycles could be identified effectively from the sedimentary record. Then, we can inverse the distribution model and stacking patterns of these cycles, restore the ancient relative sea-level trends, and finally deduce the favorable salt- and potash-forming phases from the low-stand depositional system. On the basis of these principles, a case study has been taken in the Triassic strata of the Guang’an area, in the central Sichuan Basin. Our result show that the interval between the Fifth Member of the Jialingjiang Formation to the First Member of the Leikoupo Formation is the most potential salt-and potash-forming layer, which is consistent with the potassium-rich layer recognized in the drill cores. It shows that this method could effectively identify potassium rich layer from the marine carbonate platform.

Key words: marine carbonate platform, depositional cycles, potassium-rich layer, well logging response, triassic, sichuan basin