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中国现阶段干酪根高演化阶段裂解气和原油裂解气探明储量占总储量26%以上,有必要系统研究该类天然气的形成、分布特征及下一步勘探方向。在大量源岩高演化生烃模拟和原油裂解模拟实验基础上,结合国内外裂解气研究成果,进一步分析了原油、海相—湖相泥岩及湖相煤系源岩裂解气的成因特征,并提出了5种成藏模式。原油裂解一般认为地温大于150℃以上时发生,实验证实一些地区在高于190℃才开始形成裂解气;烃源岩裂解气主要是干酪根芳甲基和终端甲基断裂,海相泥岩在RO值接近3%时裂解生气潜力接近枯竭,湖相煤系源岩在RO值为2.5%～5%时仍有较大的生成甲烷潜力,该阶段生气量占总生气量20%以上,而湖相泥岩裂解潜力介于二者之间,相对而言煤系源岩裂解气最具有潜力。裂解气主要具有古隆起原油裂解气、古风化—岩溶斜坡源岩裂解气、致密砂岩煤系源岩裂解气、特殊储集体裂解气、煤层—页岩源内裂解气5种成藏模式,古老海盆古隆起和斜坡、海陆过渡相盆地致密砂岩、中新生代湖相盆地特殊储集体是重要的勘探方向。
At present, the proven reserves of pyrolysis gas and cracked gas of crude oil in the evolution stage of kerogen in China account for more than 26% of the total reserves. It is necessary to systematically study the formation and distribution characteristics of this kind of natural gas and the exploration direction in the next step. Based on a large number of high-level source rock hydrocarbon generation simulations and crude oil cracking simulation experiments, combined with the research results of pyrolysis gas at home and abroad, the genetic characteristics of crude oil, marine facies-lacustrine mudstone and lacustrine coal seam source rock are further analyzed. Five kinds of accumulation models are proposed. It is generally believed that cracking of crude oil occurs when the ground temperature is higher than 150 ° C. Experiments have shown that pyrolysis gas begins to form in some areas above 190 ° C. Pyrolysis gas from the source rock is mainly composed of krypton methyl and terminal methyl. When the value is close to 3%, the potential for pyrolysis is close to exhaustion, and the coal source rocks in the lacustrine coal phase still generate large methane potential when the RO value is 2.5% ~ 5%. The amount of gas generation in this phase accounts for more than 20% Phase mudstone pyrolysis potential lies in between the two, relatively speaking, coal-derived source rock pyrolysis gas has the most potential. The pyrolytic gas mainly consists of paleo-uplift pyrolysis gas, paleoclimate-karst slope source rock pyrolysis gas, tight sandstone coal source rock pyrolysis gas, special reservoir pyrolysis gas, and coal seam-shale source pyrolysis gas. The ancient basin Tight sandstone of paleo-uplift and slope, transitional facies of the sea-land transition and special reservoirs of the Meso-Cenozoic lacustrine basin are important exploration directions.