Quantitative estimation of inter layers heterogeneity characteristics of volcanic reservoir： taking one member of Yingcheng formation in Xudong area for an example

Abstract：Due to few researches on volcanic reservoir heterogeneity, and in order to deeply un- derstand the structural characteristics of reservoir in micro-scale and provide reference to the effective exploitation of volcanic reservoir, the characteristics of inter layer heterogeneity of volcanic reservoir were quantitatively studied. one member of Yingcheng cretaceous formation In this research, the volcanic gas reservoir of in Xudong area, Xushen gas field was taken as an example. At the same time, the genesis and impact factor of inter layer heterogeneity of vol- canic reservoir and its influence to the reservoir development are also discussed. In this process, 56 core analysis data and 275 statistics of samples of reservoir properties were ana- lyzed, and 32 well log interpretation data were used. Methods of geological statistics and arith- metical operation means were used. The methods of core analyses combined with methods of well logging results statistics used to study the characteristics of inter layers heterogeneity of volcanic reservoir are presented. The results show that the inter layer heterogeneity of studied horizon volcanic reservoir in the aimed area was the strongest in terms of mass, whereas the in- ter layer heterogeneity of the YCII1 single layer, which was the leading layer, was the weakest among the four layers with a vertical permeability of more than half the cross range permeabili- ty. As a whole, variations of reservoir permeability in cross range were far bigger than those in vertical direction. The impact factors of inter layer heterogeneity of volcanic reservoir include the structural functioning, volcanic eruption characteristics, volcanic lithology, volcanic litho- facies and diagenesis, where the structural functioning and diagenesis took the dominant roles. Taking the variation coefficient of permeability as an index, the reservoir development condi- tions were researched. The results show that the reservoir development often occurred in the areas where the variation coefficient of permeability was smaller than 0.5. Then in areas where the permeability variation coefficients were between 0.5 and 0.7, reservoir development took the second role. All the strong inter layer heterogeneity of volcanic reservoir mainly distributed in the northwest and southeast of the study area, should be fully considered while designing and developing the process.