油气重力异常的特征与分离

The feature and separation of hydrocarbon gravity anomaly

华东有色地质勘查局814队, 镇江212005

The 814 Team, East China Bureau of Nonferrous Geological Exploration, Zhenjiang 212005

本文根据柴达木盆地SB和NBS两地区高精度重力测量成果, 探讨了天然气(油)藏上的重力低值异常(或称负重力效应)的特征、成因与分离方法。本文指出：在有天然气(油)藏的地区, 因含油气层与含水层之间、储集层与盖层之间以及由于长期烃渗漏结果, 自油气藏本身到地表与四周围岩之间都存在着负密度差, 因而绝大多数油气藏上均有重力低值异常显示, 只不过有些异常信息较弱而已, 目前关键问题是要进行高精度采集, 以发现与油气相关的信息；另一方面要提高解释水平, 要善于识别与区分油气和非油气异常, 并设法从叠加场中将油气异常分离出来。

In accordance with the high-accuracy gravity measuremens in the SB and NBS areas of Tsaidam Basin, the feature,genesis,and separtion of low-value gravity anomly above oil and gas mpls are discussed. It is pointed out that in the areas containing oil and gas pools, negative density contrast exists between the hydrocrbon and the surrounding rocks. So the low-value gravity anomalies apperar above most oil and gas pools. Some anomalies are just very weak. At present, the key problem is to carry out high-accuracy acquisition so as to discover information related to oil and gas. Moreover, the inter pretation level of technicians should be raised. It is necessary to recognize and distinguish hydrocarbon anomaly and non-hydrocarbon anornaly and separtate the anomalies from the supermposed field.