The Logging Response Characteristics and Identification of Yingcheng Formation Volcanic Rocks in Changling Fault Depression,Songliao Basin

There are maily developing six kinds volcanic rocks in Changling fault depression: volcanic breccia、tuff,tuff lava,rhyolite,basalt and andesite by data of 26 wells.There are the different logging responses amang the different volcanic rocks,natural gamma values are increasing from the basic,intermediate to acid rock,and in the acidic rocks,the natural gamma of pyroclastic rocks with high tuffaceous is greater than volcanic lava.the difference of acoustic logging is almost no difference,but the density logging value is reduced.The distribution range of the neutron porosity of Rhyolite is larger,the distribution range of the neutron porosity of andesite and basalt are more concentrated,while the distribution range of the neutron porosity of the tuff and tuffaceous are also larger.We can use three-porosity and natural gamma logging cross plot to identify the volcanic,which,the effect of the acoustic and natural gamma cross plot is the best identifying volcanic rocks,it is easy to identify the basic rocks,intermediate rocks and acid rocks,and it can also be better distinguished between pyroclastic rocks and volcanic lava in acid rocks.In addition,acoustic and density cross plot is the better,it is easily to identify basic rock,intermediate rock and acid rock.