黄骅坳陷古近系深层烃源岩成烃演化特征

Hydrocarbon generation from Paleogene deep source rocks in Huanghua Depression

黄骅坳陷古近系深层烃源岩普遍存在超压现象。热压模拟实验、烃源岩自然演化和勘探实例研究表明,深层烃源岩演化明显受到超压的抑制。板深35井中的烃源岩虽然都处于超压系统内,但R0值与深度关系不连续,分为不平行的5个梯度段,低R0值梯度段对应高TOC、S2和(或)S1含量段,高R0值梯度段对应低TOC、S1和S2含量段。在超压早期发育、原始有机质丰度高和有机质热演化产物大量滞留的情况下,超压对有机质的热演化具有明显的抑制作用。

Overpressure developed in the Paleogene of Huanghua Depression. Obvious overpressure constraint of deep source rock evolution was found through high temperature and pressure simulation experiment, natural thermal evolution and geological case studies. The R0 profile in Well BS35 is discontinuous with 5 nonparallel segments situated in over-pressured system, low R0 gradients coincide with high TOC, S2 and/or S1 contents, high R0 gradients coincide with low TOC, S1 and S2 contents. This demonstrates that early developed overpressure, high original TOC contents of source rocks and the retention of the pore fluids, are the 3 important factors affecting overpressure constraint of organic-matter maturation, which is quite important for clearly understanding petroleum exploration.