本文關鍵詞： 高-過成熟頁巖 天然氣地球化學 頁巖氣成因 成因模式 頁巖氣賦存狀態(tài)　出處：《中國地質大學(北京)》2017年博士論文　論文類型：學位論文

【摘要】：高-過成熟(Ro2.0%)是川渝鄂地區(qū)下古生界海相及南華北盆地下二疊統(tǒng)海陸過渡相富有機質頁巖的重要特征之一。論文分析了川渝鄂地區(qū)下古生界海相和南華北盆地下二疊統(tǒng)海陸過渡相頁巖中天然氣的地球化學異常和頁巖氣成因,探討了下寒武統(tǒng)頁巖中氮氣來源和富集機理,建立了頁巖氣演化階段模型及高含氮頁巖氣成因模式,提出了頁巖氣來源及賦存狀態(tài)的同位素判識方法,主要取得了以下認識:(1)高-過成熟頁巖中天然氣地球化學特征往往出現煤型氣與油型氣難以區(qū)分的異�，F象。海相與海陸過渡相高-過成熟頁巖中天然氣地球化學的主要差異在于頁巖氣中的非烴組分,特別是體現在CO_2含量及其碳同位素組成的差異。海陸過渡相頁巖氣主要分布在CO_2含量大于5%且δ~(13)C(CO_2)值小于-10‰的范圍內,而海相頁巖氣則主要分布在CO_2含量小于5%且δ~(13)C(CO_2)值大于-15‰的范圍內。(2)通過對秭地1井下寒武統(tǒng)和南華北盆地下二疊統(tǒng)頁巖氣中烷烴碳同位素倒轉的成因分析,認為兩個地區(qū)頁巖氣同位素倒轉主要是頁巖氣在高-過成熟階段與水及含鐵金屬發(fā)生反應引發(fā)的瑞利分餾所導致。四川盆地代表性的龍馬溪組頁巖氣鉆井數據表明,頁巖氣中甲烷、乙烷碳同位素倒轉程度與地層壓力系數及初始產氣量具有良好的正相關關系,對頁巖氣藏保存程度具有指示意義。(3)在分析了研究區(qū)頁巖氣地球化學特征的基礎上建立了頁巖氣演化階段模型。結合川渝鄂地區(qū)下寒武統(tǒng)頁巖氣地質特點建立了三種高含氮頁巖氣成因模式,即有機質熱解成因模式、大氣成因模式和復合成因模式,并對以上模式的主控因素進行了分析,對下寒武統(tǒng)頁巖氣勘探具有指導意義。(4)建立了頁巖氣來源和賦存狀態(tài)的同位素判識方法,通過研究川渝鄂地區(qū)海相頁巖氣來源組成發(fā)現,隨著頁巖成熟度的增加,頁巖氣中油裂解氣的比例降低。對南華北盆地海陸過渡相頁巖氣中游離氣和吸附氣含量進行計算并對比測井解釋結果發(fā)現,該方法計算結果與測井解釋結果具有良好的可對比性。論文系統(tǒng)研究了高-過成熟頁巖中天然氣地球化學成因及模式,延伸了頁巖氣地球化學的地質應用,對我國頁巖氣勘探實踐具有一定的參考意義。
[Abstract]:) is one of the important characteristics of the Lower Paleozoic marine facies in Sichuan, Chongqing and Hubei areas and the southern North China basin underground Permian transitional facies rich in organic matter shale. The paper analyses the Lower Paleozoic marine facies and the South North China Basin in Sichuan, Chongqing and Hubei regions. Geochemical anomalies of natural gas in the transitional facies shale of the Permian sea and land and the origin of the shale gas, The source and enrichment mechanism of nitrogen gas in Lower Cambrian shale are discussed. The evolution stage model of shale gas and the genetic model of high nitrogen content shale gas are established, and the isotopic identification method of source and occurrence state of shale gas is put forward. The main results are as follows: (1) the geochemical characteristics of natural gas in the overmature shale often occur abnormal phenomenon that it is difficult to distinguish the coal-type gas from the oil-type gas. The geochemistry of natural gas in the marine and oceanic transitional facies and the over-mature shale. The main difference in science lies in the non-hydrocarbon components of shale gas, In particular, the difference in CO_2 content and carbon isotopic composition shows that the marine and continental transitional shale gas mainly distributes in the range of CO_2 content greater than 5% and 未 ~ (13) C _ (13) C _ (C) _ (CO _ (2)) value less than -10 鈥，

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