油气运移过程中的“高速刹车”稠化机理探讨——以渤海湾盆地东营凹陷南坡东段为例

Mechanism of “high-speed braking” effect on heavy oil formation during hydrocarbon migration: a case study of the eastern part of southern slope of Dongying Sag, Bohai Bay Basin

杜振京

DU Zhenjing

中国石化 胜利油田分公司 油气勘探管理中心, 山东 东营 257000

Management Center of Oil and Gas Exploration, Shengli Oilfield Company, SINOPEC, Dongying, Shandong 257000, China

油气在运移过程中由于聚集成藏而产生"高速刹车"现象，大分子物质发生阻塞无法通过，而只有小分子物质可以继续运移。王146地区位于渤海湾盆地东营凹陷南坡东段构造鞍部，该地区沙河街组四段储层中的原油地面黏度相比低部位的丁家屋子构造带和高部位的八面河构造带要高。利用"高速刹车"效应来解释这一现象的出现，并分析了该区超稠油油藏的形成机理；同时，从砂体厚度、地层倾角和地层异常压力变化特征3个方面，探讨了"刹车效应"形成的地质条件，并根据研究区3个构造带原油的主峰碳、∑C21-/∑C22+以及降解程度的差异性，为原油"高速刹车"稠化机理的存在找到了有利的地球化学证据。

The phenomenon of "high-speed braking" occurs due to the accumulation of oil and gas during hydrocarbon migration. Then the macromolecular substances are blocked and cannot pass through, while the small molecules can continue to migrate. The well Wang 146 area is located in the eastern part of the southern slope of the Dongying Sag in the Bohai Bay Basin. The viscosity of crude oil in the fourth member of the Shahejie Formation in this area is higher than that of the Dingjiawuzi structural belt in the lower part and the Bamianhe structural belt in the higher part. The "high-speed braking" effect was used to explain the occurrence of this phenomenon, and the formation mechanism of ultra-heavy oil reservoirs in this area was analyzed. At the same time, the geological conditions for the formation of the "brake effect" were discussed from three aspects: sand body thickness, formation inclination, and the characteristics of abnormal formation pressure. The differences in the main peak carbon, ∑C21-/∑C22+, and the degree of crude oil degradation in the three tectonic belts of the study area can be used as favorable geochemical evidence for the formation of heavy oil caused by the "high-speed braking" effect during crude oil migration.

https://doi.org/10.11781/sysydz202001126