含油气岩系中含铵矿物研究现状与前景

研究表明,在含油气岩系中,当有机质发生热演变而成熟、并逐渐向烃类转变的整个过程中,氮主要以NH+₄的形式释放出来而进入孔隙流体与周围介质 (成岩矿物 )相互作用,最重要的机制是NH+₄可取代粘土矿物 (如伊利石,I/S混层矿物等 )层间的K+而参与成岩作用,形成含铵矿物,这一过程中氮的地球化学性质发生了重要变化,含铵矿物中固定 -NH4的富集状况与有机质成熟度及烃类运移有关。通过研究成岩和油气生成、运移、聚集过程中氮的岩石地球化学行为及其控制因素,可将固定 -NH₄作为有机质成熟度和油气运移路径的一种新的、有意义的示踪剂。

Current Situation and Development in Study on NH4-bearing Minerals in Oil and Gas-bearing Rocks

Nitrogen,like carbon and oxygen,is one of important elements in Organic matt er cor molecule In the oil an d gas-bearing rocks, with the maturation and formation of into hydrocarbon from organic matters, nitrogen is released into pore fluids to form NH+₄ and interact s w ith diagenetic minerals(e.g.authigenic clay minerals). The most important mechan ism that is NH+₄ substitutes for K+ in interlayer sites of clay minerals ( e.g. illite, ilite/smectite) and forms the NH₄-bearing minerals. The significant ch anges of the geochemical properties of nitrogen have taken place during the diag enetic process. The concentrations of fixed-NH₄ in the NH₄-bearing minerals is closely related to maturation of organic matter and mig ration of hydrocarbon. The fixed-NH₄ concentration of authigenic clay minerals increase gradually with the organic maturation. The diagenetic clay minerals al ong the hydrocarbon migration pathways were able to “catch” more NH+₄ duri ng hydrocarbon migration and accumulation, and thus its fixed-NH₄ concentration is higher than other places.By means of many studies of the nitrogen lithogeochem isty and its influenced factors during diagenesis and hydrocarbon formation, migrati on as well as accumulaton, it shows that the new and potential use of fixed-NH₄ co ncentration as an indicator of organic maturity and hydrocarbon migration pathways.