莺歌海盆地“暗点”型气藏地震识别技术研究

莺歌海盆地乐东区深层与东方区具有类似的成藏条件,是高温高压领域获取下一个重大勘探突破的最现实区域.但是该区已钻遇的“亮点”型储层物性差,普遍表现为低孔-特低渗特征,而区域基础规律研究表明,区域潜在甜点储层在地震上应该表现为“暗点”型特征.但是,“暗点”型储层在叠后地震资料上无法有效识别,如何准确预测“暗点”型储层是乐东区勘探新突破的重点攻关方向.本文针对“暗点”识别难的问题,提出了基于叠前地震资料的储层预测技术.从岩石物理出发系统性地梳理该区“暗点”型储层的地球物理特征,总结出其具有“叠加无反射、近道弱波峰、远道弱波谷、道集极性反转”的规律,根据该规律建立了Fstack属性重构算法,利用该算法开展甜点储层筛选并进行“暗点”储层预测,结合道集资料、反演结果等地球物理信息,最终确定潜在“暗点”型气层的分布范围.钻井结果证实该技术对乐东区深层潜在“暗点”型储层具有很好的预测效果.

Seismic recognition techniques of dark spot gas reservoirs in Yinggehai basin

There is a similar accumulation condition in the deep of the Ledong district and Dongfang district,which is the most realistic area for more exploration breakthroughs in the High-Temperature and High-Pressure(HTHP)fields in Yinggehai basin.The physical properties of bright spot reservoirs in Ledong are poor,most of them are low porosity and low permeability reservoirs.The study of regional rock physical law shows that the potential desserts reservoir in Ledong district should be characterized by“dark spot”features which are difficult to directly identify on seismic profiles.In order to solve the problem of difficult identification of“dark spot”reservoir,this paper puts forward a“dark spot”reservoir prediction technology based on pre-stack seismic data.First of all,we systematically sort out the geophysical characteristics of the“dark spot”type reservoir,it has different amplitude characteristics on partial angle stack seismic data.According to this rule,This paper defines the“Fstack”attribute,and establishes the calculation formula of the attribute.Combined with the regularities of distribution of the attribute anomaly and the comprehensive analysis of geophysical information such as inversion,the distribution range of the“dark spot”gas reservoir can be determined finally.And the drilling results prove that the technology has a good predictive effect on the deep potential“dark spot”reservoirs in Ledong district.