华北海陆过渡相泥岩可溶有机质组成特征

Composition characteristics of soluble organic matter in marine-continental transitional mudstone in North China

通过溶剂抽提和气相色谱/质谱(GC/MS)分析,对华北海陆过渡相泥岩可溶有机质组成进行研究。结果表明华北太原组—山西组泥岩的溶剂抽提率介于0.02%~0.23%,太原组抽提率略高于山西组,但均低于华南龙马溪组海相页岩;甲醇溶剂抽提率最高,正己烷溶剂抽提率最低;泥岩可溶有机质由大量的杂原子化合物和少量的脂肪烃组成,杂原子化合物中酯类最多,其次为醇类及卤代烃,脂肪烃以烷烃及脂环烃为主;太原组泥岩中的酯类含量略低于山西组,霍西泥岩中醇类含量较高,豫东泥岩中脂肪烃稍多;正己烷抽提物主要为酯类和醇类,氯仿抽提物主要为酯类、卤代烃和醇类,丙酮抽提物主要为醇类,甲醇抽提物主要为酯类、脂肪烃、醇类和醛类。研究认为泥岩中醇类含量、脂肪烃和卤代烃含量在一定程度上可以指示沉积环境受古海洋影响的强烈程度,可作为页岩气藏储层沉积相划分的参考或依据。

The composition of soluble organic matter in marine-continental transitional mudstone in North China was studied based on solvent extraction and gas chromatography-mass spectrometry(GC-MS)analysis.The results show that the solvent extraction rate of mudstone of the Taiyuan formation-Shanxi formation in North China is between 0.02%and 0.23%,and the extraction rate of the Taiyuan formation is slightly higher than the Shanxi formation,but lower than marine shale of the Longmaxi formation in South China.Methanol has the highest extraction rate and n-hexane has the lowest.Mudstone soluble organic matter consists of a large number of heteroatom compounds and a small amount of aliphatic hydrocarbons.Esters are the most in heteroatom compounds,followed by alcohols and halogenated hydrocarbons.The aliphatic hydrocarbons are mainly alkanes and alicyclic hydrocarbons.In contrast,the content of esters in the mudstone of the Taiyuan formation is slightly lower than that of the Shanxi formation,the content of alcohols in the Huoxi mudstone is higher,and there are a little more fatty hydrocarbons in the mudstone of Eastern Henan;Hexane extracts are mainly esters and alcohols,chloroform extracts are mainly esters,halogenated hydrocarbons and alcohols,acetone extracts are mainly alcohols,and methanol extracts are mainly esters,aliphatic hydrocarbons,alcohols and aldehydes.It is concluded that the contents of alcohols,aliphatic hydrocarbons and halogenated hydrocarbons in the mudstone can be used to indicate the effectiveness of the paleoocean on the sedimentary environment to a certain extent,which may form a reference or basis for sedimentary facies division of shale gas reservoirs.