地球化学
地毬化學
지구화학
GEOCHIMICA
2014年
5期
510-517
,共8页
干酪根%气体特征%模拟实验%三塘湖盆地
榦酪根%氣體特徵%模擬實驗%三塘湖盆地
간락근%기체특정%모의실험%삼당호분지
kerogen%gas characterization%simulation experiments%Santanghu Basin
针对三塘湖盆地的主力烃源岩二叠系芦草沟组泥质烃源岩开展封闭体系和半开放体系热模拟实验，前者将干酪根密封在金管中开展实验、后者直接对烃源岩样品进行压机半开放体系热解模拟，对实验中生成气体的组分和稳定碳同位素进行分析。实验结果显示，两种热解方法以无机气体生成为主，包括CO2、H2、H2S 和 N2等，其中 CO2含量最丰富，这与样品干酪根中丰富的氧含量一致。半开放体系模拟实验温度达到480℃时，气态烃的含量达40.64%，其中甲烷含量达到26.10%，封闭体系中随着模拟温度升高烃类气体产物的碳同位素呈现先变轻后变重的趋势，但同位素分馏程度不大， CH4气体的δ13C 值分布在-40.2‰~-46.6‰之间， C2H6分布在-34.3‰~-38.0‰之间， C3H8分布在-33.6‰~-36.0‰之间，而CO2气体δ13C值分布在-32.8‰~-28.8‰之间。三塘湖盆地针对气藏的勘探已经有所发现，但有关气藏的地球化学特征报道较少，该工作中的模拟实验结果可为三塘湖盆地深入的气藏地球化学勘探提供基础数据。
針對三塘湖盆地的主力烴源巖二疊繫蘆草溝組泥質烴源巖開展封閉體繫和半開放體繫熱模擬實驗，前者將榦酪根密封在金管中開展實驗、後者直接對烴源巖樣品進行壓機半開放體繫熱解模擬，對實驗中生成氣體的組分和穩定碳同位素進行分析。實驗結果顯示，兩種熱解方法以無機氣體生成為主，包括CO2、H2、H2S 和 N2等，其中 CO2含量最豐富，這與樣品榦酪根中豐富的氧含量一緻。半開放體繫模擬實驗溫度達到480℃時，氣態烴的含量達40.64%，其中甲烷含量達到26.10%，封閉體繫中隨著模擬溫度升高烴類氣體產物的碳同位素呈現先變輕後變重的趨勢，但同位素分餾程度不大， CH4氣體的δ13C 值分佈在-40.2‰~-46.6‰之間， C2H6分佈在-34.3‰~-38.0‰之間， C3H8分佈在-33.6‰~-36.0‰之間，而CO2氣體δ13C值分佈在-32.8‰~-28.8‰之間。三塘湖盆地針對氣藏的勘探已經有所髮現，但有關氣藏的地毬化學特徵報道較少，該工作中的模擬實驗結果可為三塘湖盆地深入的氣藏地毬化學勘探提供基礎數據。
침대삼당호분지적주력경원암이첩계호초구조니질경원암개전봉폐체계화반개방체계열모의실험，전자장간락근밀봉재금관중개전실험、후자직접대경원암양품진행압궤반개방체계열해모의，대실험중생성기체적조분화은정탄동위소진행분석。실험결과현시，량충열해방법이무궤기체생성위주，포괄CO2、H2、H2S 화 N2등，기중 CO2함량최봉부，저여양품간락근중봉부적양함량일치。반개방체계모의실험온도체도480℃시，기태경적함량체40.64%，기중갑완함량체도26.10%，봉폐체계중수착모의온도승고경류기체산물적탄동위소정현선변경후변중적추세，단동위소분류정도불대， CH4기체적δ13C 치분포재-40.2‰~-46.6‰지간， C2H6분포재-34.3‰~-38.0‰지간， C3H8분포재-33.6‰~-36.0‰지간，이CO2기체δ13C치분포재-32.8‰~-28.8‰지간。삼당호분지침대기장적감탐이경유소발현，단유관기장적지구화학특정보도교소，해공작중적모의실험결과가위삼당호분지심입적기장지구화학감탐제공기출수거。
This work was carried out to study the geochemical characteristics of gaseous pyrolysates from Permian argillaceous source rocks of Santanghu Basin, from the closed and semi-open systems, respectively. Kerogens prepared from the source rocks were sealed into golden tubes for the closed-pyrolysis, while the source rocks were used directly for the semi-open system. The composition and stable carbon isotope of the gas generated were analyzed. The results show that, for both pyrolysis systems, inorganic gas were the main products including CO2, H2, H2S, N2. The proportion of CO2 was the highest due to the abundant oxygen content in the kerogens; for the semi-open system, the relative percentage of gaseous hydrocarbons can be up to 40.64%, and the relative percentage of methane is as high as 26.10% when the temperature reaches 480 ℃. With the increasing temperature, the stable carbon isotope ratios of gaseous hydrocarbons from closed system first become lighter and then heavier, with the δ13C of CH4 ranging from -40.2‰ to -46.6‰, C2H6 -34.3‰--38.0‰, C3H8 -33.6‰--36.0‰ and CO2-32.8‰--28.8‰. Gas reservoir has been found in the Santanghu Basin, NW China, but little have been reported on the geochemical characteristics of the gas. Basic data are provided in this work for further petroleum exploration of the Santanghu Basin.
