Research On The Volcanic Reservoir Characteristics And Favorable Areas Optimization Of Yingcheng Formation Of Changde Area

There are three deep gas fields in Daqing： Xushen，Changde，Shengping whichhave natural gas reserves2399.85x108m3. Through the Eleventh Five-Year Plan ofscientific and technological research，it has developed a production capacity of14x108m3. However，there is still an unused reserve of1123.94x108m3that is "lowgrade，low efficiency and low yield". During the period of Twelfth Five-Year Plan，the production capacity of Daqing natural gas should reach50x108m3. And meanwhileChangde gas field will be an important developing area.Based on some basic information such as drill core， well logging， seismic dataand so on， this subject conducts the sequence division and comparison of Yingchengvolcanic gas layer as well as recognition of volcanic lithofacies within subdivisionlayer which figures out plane distribution characteristics of volcanic lithofacies of thetarget area. Moreover，volcanic rock reservoir’s characteristics of petrophysicalproperties，the connections between lithology-lithofacies and physical property， rockreservoir characteristics and so on also get further analyzed and summarized. Finally，prediction method of volcanic rock reservoir fractures is explored with predictingeffective volcanic rock reservoirs and selecting favorable areas by optimized methods.Main results are as follows：1. Establish stratigraphic sequence division standard based on lithology，electric property and seismic response characteristics and unify the gas group divisionof Yingcheng Formation and Xushen gas field.2. Find that there are mainly two kinds of types of volcanic lithofacies in theYincheng area：eruption phase and overflow phase. Volcanic lithofacies，while theformer is the main type. Six volcanic bodies are recognized and fs6with an area of27.6km2owns the maximum distribution range.3. Yingcheng Formation No.1Member volcanic reservoir porosity is mainly3.2%～8.8%，and permeability is less than0.05mD，which is the low-permeability gasreservoir; Heat wave，hot debris flow，fall deposits and volcanic-clastic sedimentaryrock are development. Hot pyroclastic flow subfacies is better than heat wave and falldeposits subfacies.4. Reservoir spaces have diverse types and get developed generally. There arethree main composite types. The reservoir pore structure is classified into three classes.And the main class is Class II，followed by Class III while Class I only occupies afew. 5. Select two favorable areas as fs9，fs101well regions by optimization throughsetting20m as the lower limit of favorable Yingcheng Formation volcanic gas layersas well as combining distribution characteristics of reservoirs fractures.