构造生烃

生烃是岩石中所含的有机质产生流体有机化合物的化学反应。岩石有机质化学反应存在两种系统：封闭系统和开放系统，随着埋深加大，烃源岩越来越致密，岩石的化学反应逐渐由开放系统转变为封闭系统。目前的生烃理论仅仅是开放系统下烃源岩成熟与生烃理论，烃源岩成熟与生烃是不匹配的。封闭系统下烃源岩成熟与生烃是不匹配的，烃源岩成熟但不生烃，而是形成另外一种成熟的固体有机质。大多数情况是烃源岩为半封闭系统，烃源岩处于欠生烃状态。构造运动形成的断层和裂隙将烃源岩与疏导层沟通，烃源岩迅速由封闭、半封闭系统转变为开放系统。这种生烃系统的转变形成短时间内过量生烃，笔者将这种生烃作用命名为构造生烃，意味着构造运动期即为主生烃期，伴随着多次构造运动可以形成多个幕式生烃高峰。构造生烃理论开拓两个极其重要的勘探领域：第一，新构造勘探。以往认为已经过了生、排烃期的构造得以解放，如渤海湾郯庐断裂带第四纪圈闭不是过了主生烃期，而是正处于构造生烃的过生烃高峰期。以PL19-3为代表的油气运聚强度只有构造生烃能够解释；第二，超深勘探，特别是天然气勘探。深层勘探的下限将大大延伸，生烃门限，特别是生气门限将大大加深，仅生烃而言万米都不是天然气勘探的极限。

Hydrocarbon generation by structural movements

Hydrocarbon generation is a kind of chemical reaction and organic material in source rock forms fluid hydrocarbon. There are two types of chemical reaction systems： open system and closed system. The source rock becomes denser as burial depth increased, and chemical reaction system becomes closed system. Current generation theory is just a hypothesis that maturity of source rocks in open system matches hydrocarbon generation. However, it is not happened in closed system. Maturity of source rock is progressively degraded without hydrocarbon generation in closed system; the organic material of source rocks formed another kind of solid organic material. In most eases source rocks are in semi-closed system and hydrocarbon generation is not much. Since faults and fractures formed by structural movements in short time connected source rocks and permeable beds, chemical reaction system changed from open system to closed system rapidly and caused excessive hydrocarbon generation in short time. This process was named as hydrocarbon generation formed by structural movements which means main hydrocarbon generated in the period of structural movements and each movement is related to a peak of hydrocarbon generation if several movements exist. The new theory can be applied to find new reservoirs from traps which was supposed to have past hydrocarbon generating period and the gas generation threshold was extended.