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渤海湾盆地歧口凹陷超压对有机质热演化、有机酸生成和水岩反应具有明显的抑制作用。在化学动力学模型中加入超压因子增加反应活化能,即可用于超压条件下有机质热演化和成岩作用的模拟。歧口凹陷深层(>3500m)主要为沙河街组(始新—渐新世)。在沙河街组沉积末期沙河街组三段(沙三段)就进入晚成岩阶段A1期,烃源岩开始生烃,生、储、盖层发育史与圈闭发育史匹配良好,油气藏开始形成。在东营组沉积时期(渐新世)—新近纪,沙河街组大部分地层处于晚成岩阶段A1—A2期,是其主要成藏期。现今沙河街组一段、二段和三段的上部仍处于晚成岩阶段A1—A2期,有利于油气藏的形成。然而,沙三段的下部在歧口凹陷的北部地区已进入晚成岩阶段BC期,镜质组反射率Ro≥1.3%,烃源岩处于高过成熟阶段,储层物性较差,不利于成藏,但在南部地区的沙三段下部还处于晚成岩阶段A1-A2期,生、储、盖层发育,是油气聚集的有利地区。
The overpressure in the Qikou Depression of Bohai Bay Basin significantly inhibited the evolution of organic matter, the formation of organic acids and the water-rock reaction. By adding overpressure factor to the chemical kinetic model to increase the reaction activation energy, it can be used to simulate the thermal evolution and diagenesis of organic matter under overpressure condition. The deep Qikou depression (> 3500m) is mainly composed of Shahejie Formation (Eocene-Oligocene). In the late stage of Shahejie Formation sedimentation, the third member of Shahejie Formation (Es3) entered late stage of diagenesis stage A1, hydrocarbon generation began to occur in source rocks, development history and trapping history matched well with hydrocarbon reservoir, caprock, form. During the sedimentary period of Dongying Formation (Oligocene) - Neogene, most of the strata in Shahejie Formation are in the late-diagenetic stage of A1-A2, and are the main hydrocarbon accumulation periods. Nowadays, the upper part of the first, second and third sections of Shahejie Formation is still in the late diagenetic stage of A1-A2, which is favorable for the formation of oil and gas reservoirs. However, the lower part of Es3 in the northern part of Qikou sag has entered the late diagenetic stage BC, the vitrinite reflectance Ro ≥ 1.3%, the source rock in the over-mature stage, poor reservoir properties, is not conducive to However, in the lower part of Es3 in the southern area, it is still in the stage of late diagenesis A1-A2, with the development of genesis, reservoirs and caprocks, which is a favorable area for oil and gas accumulation.