徐家围子断陷营城组火山岩及气藏分布

YINGCHENG-FORMATION VOLCANIC ROCKS AND GAS RESERVOIR DISTRIBUTION IN XUJIAWEIZI FAULT DEPRESSION

徐家围子断陷营城组火山岩是该区深层天然气勘探的重要领域.根据钻井揭示结果,并结合地质、地球物理综合分析,探讨了徐家围子断陷营城组多期次火山岩分布规律,明确了储层发育的控制因素,分析了气藏富集的控制因素,预测了气藏分布.研究结果表明：营城组火山岩可划分为两段六期,火山口区沿断裂带展布,酸性火山岩与中基性火山岩在火山口区展布规模差异大;火山岩储层受岩性、岩相控制,酸性火山岩优于中基性火山岩,平面上火山口区最优,远火山口区最差;纵向上受期次控制,各期次上部发育优质储层;酸性火山岩火山口区、近火山口区气藏主要受构造控制,为岩性—构造气藏,远火山口区发育致密岩性气藏,中基性火山岩气藏整体为致密岩性气藏.研究成果为深层天然气勘探指明了方向,取得了良好的勘探效果。

The volcanic rocks in Yingcheng Formation （K1yc） of Xujiaweizi Fault Depression are the key field of the natural gas exploration in the deep layers of the region.Based on the drilling results in combination with the geological and geophysical analyses,the distribution rules of the multiple-stage volcanic rocks in the formation are discussed and then the controlling factors of the volcanic reservoir development are known,the gas accumulation controlling factors are analyzed and the corresponding reservoir distribution is predicted.The study results show that the volcanic rocks can be divided into two members and six stages.The craters are distributed along the fault belts and there is a big difference of its size between the acidic volcanic rocks and intermediate-basic volcanic rocks ; the volcanic rock reservoirs are controlled by the lithology and facies.The acid volcanic reservoirs are better than the other.The crater reservoirs are the best on horizon,while the ones far away from the craters are on the contrary; the reservoirs are controlled by the stages vertically and the high-quality reservoirs are developed in the upper parts of the stages; the gas reservoirs nearby the acidic volcanic craters and proximal regions are controlled by the structures and then the structural-lithologic gas reservoirs are accumulated,while the tight gas reservoirs are enriched in the distal facies.The gas reservoirs in the intermediate-basic volcanic rocks are tight gas reservoirs in a whole.All the achievements stated above have shown the clear direction for the deep natural gas exploration,and moreover the much better exploration effects are obtained.