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The Relationship Between Water-richness And Sedimentary Facies Of Zhiluo Formation In Ningtiaota Coal Mine

Posted on:2016-08-14Degree:MasterType:Thesis
Country:ChinaCandidate:Y ZhouFull Text:PDF
GTID:2180330509951011Subject:Geological Engineering
Abstract/Summary:PDF Full Text Request
The Ningtiaota coal mine is located in the eastern edge of Ordos Basin. Yan’an Formation is the main coal-bearing strata in Jurassic in this area, and overlying strata is Zhiluo Formation, which develops many sand bodies. The thick layers of sand provide large storage spaces for groundwater. It makes an important sense for the safety of coal mining in Yan’an Formation, after research Zhiluo Formation sandstone aquifer characteristics and rich water situation.This article is based on fully collecting field outcrops, drilling and logging information,using the theory and method of sedimentology and sequence stratigraphy to analyze sedimentary characteristics of Zhiluo Formation in the Ningtiaota coal mine and has divided the sedimentary system and identified the sedimentary facies in the study area, analyzed the Zhiluo Formation by the sequence stratigraphy, established the sequence stratus frame, and has studied the sand body spreading regularity in this sequence stratus frame. The conclusion contains the follows:1. The vertical sedimentary sequence for Zhiluo Formation in the research area can be divided into braided river sedimentary system, braided river delta sedimentary system,meandering river sedimentary system and shore shallow lacustrine sedimentary system in ascending order. This paper has identified the sedimentary facies, subfacies and microfacies in the study area.2. Based on the principle and methods for base level cycle of the high-resolution sequence stratigraphy, the Zhiluo Formation in the study area is divided into a II level sequence(SLSC1), three III level sequences and ten IV level sequences, respectively corresponding to a super long-term base-level cyclic sequence(SLSC1), three long-term base-level cyclic sequences(LSCl-LSC3) and ten mid-term base-level cyclic sequences(MSC1-MSC 10), and has established the sequence stratus frame.3. Based on the division of sedimentary system and identify the sedimentary facies to research the Zhiluo Formation’s sedimentary facies distribution in the study area. We consider the study area experienced a braided river- braided river delta- meandering river and shore shallow lacustrine of evolution, and marginal decline and uplift of tectonic cycle. In the other way, the researchers found that the east of Ordos Basin roughly showing west to east, north to south, and the sediment sources of Zhiluo Formation comes mainly from the western and northwestern edge on the higher topography.4. Furthermore, the sedimentary facies are distributed in north-south direction, mainly including sandy river skeleton, sand dam and silty sand-shale river alluvial flat, and the thick sand layers, formed by the sandy river and sand dam, provide good conditions for groundwater reservoir and development. The sandstone of this area is relatively strong water-richness.5. On the basis of hydrogeological data, comprehensive analysis that there are some inherent relationship between sedimentary facies and stratigraphic’s water-richness in Zhiluo Formation; and the study area is divided into three different water-richness zones(strong,medium and weak).
Keywords/Search Tags:sedimentary system, sedimentary facies, sequence stratigraphic framework, sandstone aquifer, water-rich capability
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