乌尔逊凹陷烃源岩细分层评价及生烃能力研究

Subdivision Evaluation and Hydrocarbon Generation Capacity of Source Rocks in Wuerxun Depression

摘要: “十三五”期间，海拉尔–依舒等外围盆地仍是大庆油田持续有效发展资源接替的重要领域，要增加0.22~0.5亿吨石油探明储量，乌尔逊–贝尔凹陷作为海拉尔盆地勘探最有前景的凹陷，为油田持续有效发展提供资源和技术保障。乌尔逊凹陷是海拉尔盆地两大主力富油凹陷之一，烃源岩研究仍停留在层段级别上，满足不了目前精细勘探的需求，还需要建立优质烃源岩识别与评价的标准，研究平面上的分布规律。本研究把层序地层学与有机地球化学相结合，将乌尔逊凹陷南二段细分为两个小层，南一段细分为八个小层；利用测井ΔLogR法计算TOC技术，对烃源岩进行分层、分级评价；同时建立乌尔逊凹陷优质烃源岩评价标准，研究确定乌尔逊凹陷优质源岩分布层系为K₁n₁₃~K₁n₁₆，其排油量的67%是由有机碳TOC > 2%的优质烃源岩所贡献。

Abstract: During the “Thirteenth Five-Year Plan” period, the peripheral basins such as Hailar-Ishu are still an important area for the sustainable and effective development of Daqing Oilfield. It is necessary to increase the proven reserves of 0.22 - 0.50 million tons of oil. As the most promising depression for exploration in the Hailaer Basin, the Wuerxun-Beir Sag provides resources and technical support for the sustainable and effective development of oil fields. The Wuerxun sag is one of the two main oil-rich depressions in the Hailaer Basin. The study of source rocks is still at the interval level, which cannot meet the current demand for fine exploration. It is also necessary to establish standards for the identification and evaluation of high-quality source rocks, and study the distribution law on the plane. In this study, the sequence stratigraphy combined with organic geochemistry is used to subdivide the southern part of the Wuerxun depression into two small layers, and the south section is subdivided into eight small layers. The TOC technique is calculated by ΔLogR method. The stratification and grading evaluation of the source rocks are carried out. At the same time, the evaluation criteria of high-quality source rocks in the Wuerxun sag are established. The high-quality source rocks in the Wuerxun depression are determined to be K₁n₁₃ - K₁n₁₆, and 67% of the oil discharge is determined by the contribution of organic carbon TOC > 2% of high quality source rocks.