Physical Property Pharacteristics And Favorable Block Prediction Of Volcanic Reservior In Xujiaweizi Fault Depression

The Xujiaweizi Fault depression is the largest igneous reservoir ever discovered in China which is located in the northern Songliao Basin.The igneous reservoir of Yingcheng Formation take a very important role in the field of deep buried gas prospecting in Songliao Basin.On the ground of low-porosity and low permeable sublayer of volcanic rocks,the studies on types and quality calculation of igneous reservoir are the problems demanding prompt solution.On the basis of completely collecting the test data of The Xujiaweizi Fault depression,we have given a further study on the reervior and calculated reservoir quality by numerical modeling.Study on the of the petrological characteristics, pore types and the diagenesis of volcanic rocks,shows that volcanic rocks types can be divided into two kinds,including lavas and pyroclastic rocks,the major volcanic rocks are rhyolite and ignimbrite which are the most important reserviors of gas.The reservior spaces include primary pore,primary facture,secondary pore and secondary fracture.While the favorable volcanic rock reserviors in this area are mainly composed of initial bubbles,micropores resulted from devitrification and secondary dissolution pores.The reservior guality are greatly effected by the diagenesis events including packing action,devitrify and dissolution.We have also discussed the pore-evolution by the evidence of geologic event and petrology,the result showed that the pore-evolution this area can be devide into five phases.Besides volcanic phase,the physical property of igneous reservoir are also affected by diagenesis of mudstone, the extent of organic material evolution deeply control dissolution porosity of volcanic rocks.Considering the impacts to reservior both by volcanic and diagenesis of mudston,making use of diagenesis numberical modeling,according to line map of volcanic phase,we have calculated reservoir quality on plane of Yingcheng Formation.The calculation results are accordance with actual verify by well test.By means of diagenesis numerieal modeling and reservoir quality Predietion in Xujiaweizi Fault depression,the studied fruit of the text can not only supply and prove the course theory of diagenesis but also can change present research situation about igneous reservoir,further the method and outcome have a very important affact on finding the developed region of benefieial reservoir and guiding the oil and gas prospecing.