Petroleum exploration in the Ordos Basin gradually expanded to the edge of the basin, but encountered difficulties on the southwestern edge. Compared with mature exploration areas inside the basin, the nature of reservoir fluids in the southwestern area is more complex. In order to better understand the oil/gas system in this area, this study conducted a detailed research on the geochemical characteristics of potential source rocks and reservoir fluids in this area.

The results show that although the Chang 7 oil group in the study area developed thicker mudstone and has a high abundance of organic matter, the low degree of thermal evolution limits its hydrocarbon production. The Chang 8 oil in the study area is the result of lateral migration of products from mature source rocks inside the basin, which can be explained by the similar biomarker characteristics and gradually changing nitrogen compounds between them. Anaerobic biodegradation is an important factor that complicates the fluid properties in the study area. It not only thickens part of the oil, but also produces secondary biogenic natural gas, mainly methane.

鄂尔多斯盆地的石油勘探逐渐扩展到该盆地的边缘，但在西南边缘却遇到了困难。与盆地内部成熟的勘探区相比，西南地区储层流体的性质更为复杂。为了更好地了解该地区的油气系统，本研究对该地区潜在烃源岩和储层流体的地球化学特征进行了详细研究。

结果表明，虽然研究区长7油组发育较厚的泥岩，有机质含量较高，但热演化程度低限制了其烃类的产生。研究区的长8油是盆地内成熟烃源岩产品横向运移的结果，这可以用相似的生物标志物特征和逐渐变化的氮化合物来解释。厌氧生物降解是使研究区域的流体性质复杂化的重要因素。它不仅使部分石油增稠，而且还产生次生生物天然气，主要是甲烷。