松辽盆地滨北地区油气勘探方向探讨

Strategy for next step oil & gas exploration in Northern Songliao Basin

松辽盆地滨北地区目前已发现深层和中浅层两套烃源岩:深层断陷层序的沙河子组和营城组发育的暗色泥岩和含煤地层及中浅层坳陷层序发育的青山口组和嫩江组暗色泥岩。该区发育有中浅层砂岩、深层砂砾岩和火山岩储集层,嫩一段、嫩二段泥岩及青一段泥岩为区域性盖层。根据地层层序和构造特征分析,认为本区勘探应遵循以下原则:①注重深层、兼探中浅层;②坳陷层序以找油为主,断陷层序以找气为主,断陷层序中应特别注意寻找类似于XS1井的火山岩气藏;③以滨北地区的逆断层带为线索,重点寻找前古近纪形成并保存下来的油气藏和新近纪以来形成的油气藏。

There are two successions of source rocks in the northern Songliao Basin, which are dark shale and coal developed in the faulted sequences of Shahezi （K1s） and Yingcheng （K1y） Formation and dark shale in the depressed sequences of Qingshankou （K2qn） and Nenjiang （K2n） Formation. Reservoir rocks include sandstone and conglomerate in the overall sequence and volcanic rocks in the lower succession of basin fillings. Regional cap rocks are the mudstones of K2 n1＋2 and K2 qn1. According to basin filling signature, tectonic evolution, and exploration experiences, the authors predict three kinds of preferred oil and gas potential targets for next step exploration. The first is volcanic reservoirs similar to the highproductive Well XS1 drilled in Daqing. The second is unconformities related to those seismic reflections of T5, T4 and T3. The upper and lower sequences of the basin fillings are different concerning tectonic evolution, stratigraphy and relevant hydrocarbon-bearing features. Oil is predominantly contained in the upper and gas is expected to be in the lower. The third is reverse fault belts which include both pre-Cenozoic reservoirs and reservoirs formed since Neogene.