Abstract: The revolution of the unconventional petroleum (e.g., tight oil and gas, shale oil and gas) at the start of the 21st century has changed our understanding of the traditional petroleum system paradigm. The over-simplified "layer-cake" and discrete "source, reservoir and cap" model established from the classic petroleum system model is no longer effective in simulating the enrichment patterns and favorable distribution of unconventional oil and gas. Coupled forward stratigraphic and petroleum system modeling can fully considers the heterogeneities of various petroleum system elements during the basin filling process, and can generate more refined geological models for numerical simulations. Such a coupled approach may be used to more effectively predict the formation process and favorable distribution of deep and unconventional oil-gas reservoirs, providing a simulation tool for quantitative evaluation of the whole petroleum system in a basin. Taking the ultra-deep Sinian Dengying Formation in the central Sichuan Basin as an example, with sparse drilling data and low-quality seismic data, a process-based forward stratigraphic modeling method was used to simulate the tectono-sedimentary evolution process of the Dengying Formation, and to generate a refined three-dimensional heterogeneous sedimentary model. Based on existing understanding of the tectonic and thermal evolution history of the Dengying Formation and the characteristics of the Sinian and Cambrian source rocks, we carried out petroleum system modeling of the Dengying Formation using the refined sedimentary model and predicted the direction of oil-gas migration and favorable accumulation areas within the Dengying Formation. Compared with the simulation results from the classic "layer-cake" basin model, the coupled stratigraphic and petroleum system modeling takes full consideration of the sedimentary heterogeneities of the Dengying Formation, and is able to simulate oil-gas accumulations within lithological traps developed by lithofacies changes within the Dengying Formation. The simulated oil-gas enrichment locations and magnitudes are more consistent with actual exploration discoveries compared with that from the traditional basin and petroleum system modeling.

Key words: forward stratigraphic modeling, petroleum system modeling, Sinian Dengying Formation, deep oil-gas, Sichuan Basin

摘要： 21世纪初开始的非常规油气(致密油气、页岩油气)革命改变了人们对传统油气系统范式的认知。基于经典含油气系统模式所建立的"蛋糕式"简单且独立的"生-储-盖"分层模式已无法有效模拟非常规油气的富集规律和有利区分布。盆地沉积充填正演模拟与含油气系统耦合模拟相结合,可充分考虑盆地沉积充填过程中各含油气系统要素的非均质性,能够形成较精细的地质模型,预测深层和非常规油气的成藏过程与有利区分布,为盆地全油气系统的定量研究提供有效的模拟手段。以四川盆地中部超深层震旦系灯影组为例,在资料匮乏和精度不高的情况下,利用基于过程约束的沉积正演模拟方法模拟灯影组的构造-沉积演化过程,建立灯影组精细的沉积相/岩相非均质性地质模型,在明确灯影组构造-热演化史以及震旦系—寒武系烃源岩发育特征的基础上,开展灯影组的沉积-成藏耦合数值模拟,预测了灯影组的油气运移方向及有利聚集区。与传统的简单层状模型的模拟结果相对比,盆地沉积充填-成藏耦合的数值模拟更充分地考虑了灯影组沉积的非均质性,能模拟灯影组内部由于沉积相变而在岩性圈闭内形成的油气聚集,模拟得到的油气富集位置和规模与实际勘探发现更吻合。

关键词: 地层正演模拟, 含油气系统模拟, 震旦系灯影组, 深层油气, 四川盆地