The Evaluation Of Deep Source Rocks And The Analysis Of Nature Gas Genesis In Yingtai Fault Depression

In2003, Jilin Oilfield had shift strategic in the direction of oil and gas exploration. JilinOilfield according Yingtai fault depression's to the source rock and reservoir conditions,positioning it as a replacement area of deep oil and gas exploration of the southern SongliaoBasin. And deployed the well Longshen101, Longshen2. They both get high-yield gas flowin the Yingcheng volcanic reservoirs. So some questions about the source rocks and thegeneration of the natural gas are very important for the exploration and deployment ofYingtai fault depression.Therefore the hydrocarbon generation potential of hydrocarbon from source rock ofYingtai fault depression was researched qualitatively and quantitatively in this paper.Theresult of source rocks qualitative evaluation shows that the main source rocks of Yingtaifault depression is Yingchang Formation and Shahezi Formation and the abundance of themare at the middle-good level. Most of the are type Ⅱ1and Ⅱ2, a small amount of type Ⅲ.They are all at high mature or over mature level. So they are good gas source rocks.According to the logging geochemistry, predicted Toc of the study area and drawing the Toccontour map of Yingcheng and Shahezi Formation. In some areas of the study area (WellLongshen1) are developed magma intrusions. So we combined the heat conduction modeland the chemical kinetics model together, take the evaluation of intrusions on the source rocksevolution. The result shows that intrusions has an effect on making the stage of hydrocarbongeneration early. At that time the cap was not formed, so the natural gas had been lost. But therange of the intrusions is small, so there is little effect on the total resource. Yingtai faultdepression had generated total11.2×1012m3gas, the Yingcheng Formation had generated6.78×1012m3, Shahezi Formation had generated4.46×1012m3. The ratio of gas that Shaheziand Yingcheng Formation had generated is1:1.5. So the Yingcheng Formation is the main gassource rocks. According to light hydrocarbon indicators can judge that the gas of Yingtai faultdepression has the characteristics of condensate co-existing gas and high-temperaturepyrolysis gas. According to carbon isotope can judge the gas of Yingtai fault depression ismainly condensate co-existing and coal type gas.