Study On Biogenic Gas Generation Period Method And Its Application In Song Liao Basin

Based on biogenic gas exploration and microorganism kinetics studing, the phsic, chemical and geological condictions which biogenic gas generation needed are discussed, combine the geological conditions of research, these conculsions can be clear: both advantangeous factors and disadvantageous factors exist in Song Liao basin. The advantageous factors are geographical position, basin scale, quick subsiding rate of the Cretaceous stratum, thickness of source rock, low temperature of plaeo- lake bottom, advantageous source-reservoir-cap rock assemblage, moderate alkalinity acidity, reducing environment, rich in organic matter, and rich in alga and weak tectogenetic movement after the Cretaceous; the disadvantageous factors are high geothermal gradient and freshwater deposit.Chemical kinetic model and biochemical kinetic model used to appraise biogenic gas generation period and generation amount are firstly established both here and abroad, two type models also successfully applied to appraise biogenic gas resource of Song Liao basin. Chemical kinetic model is established and its kinetic parameters are also demarcated, basic frequency of activation energy of geological samples is from 90 KJ/mol to 100KJ/mol, and that of CK samples is from 80 KJ/mol to 90KJ/mol. So under the low temperature, and if methanogen flourish, the biogenic gas can generate. If there is good reserivor and caprock, the biogenic gas reserivor can be formed. Biochemical kinetic model is established and the kinetic parameters are demarcated. The application of two type kinetic models shows that, he biogenic gas generation rate increases with the buried depth firstly, and then decreases when reaches to the maximum (the corresponding buried depth is 600m).A method to calcualt natural gas diffusion amount is also established, it is also applied to Song Liao basin, and the corresponding softeare is also exploered, which aim to the multi-source rocks. Combined with the chemical kinetic model and biochemical kinetic model, the loss amount of biogenic gas of Song Liao basin is calculated, which ranges from 53.66 to 133.76×10¹²m³.Using the dynamic accumulation method to count resource amount, the resource amount calculated by chemical kinetics is more than that calculated by biochemical kinetics, and the range is from 1.10×1012m3 to 3.02×10¹²m³. The resource amount calculated by material balance method ranges from 235.5×10¹²m³ to 470.8×10¹²m³. Based on the resorce appraisement, advantageous areas are predicted. A partition scheme is given, two type of source-reservoir-cap combinations are given in vertical. The lowercombination contains n2 stratum which is cap rock and qn1～n2 stratums which are source rock and reserivor.The upper combination contains m1 stratum which is cap rock and n3～m1 stratums which are source rock and reserivor. The desserts of lower combination are east and south Sanzhao sag, Heiyupao Sag, Erzhan～Alaxin region and Honggang oil field are the deserts of both two combinations.