Simulation Experiments On The Actions Between Volcanic Fluids And Source Rocks In The Songliao Basin

Recent years, with the deepening of exploration on Songliao basin, research on the deep volcanic rock associated oil and gas reservoir of Songliao basin saw great progresses. More and More exploratory wells and commercially gas flow wells carried out herein demonstrated that the deep volcanic rock oil and gas reservoir in the inner Songliao basin will be a potential oil and gas exploration region, which has been emphasized by a great deal of petroleum geologists.It was found that the deep strata of Songliao basin were featured by volcanic rocks interbedded with source rocks based on investigation of geological data. Characteristics of volcanic rocks implied that fierce volcanism occurred in this region. In the inner Songliao basin, deep volcanic rock and the interbedded source rocks cropped out at 2 formations, namely the Lower Sha Hezi Formation, the upper 1st, 2nd and 3rd Member of the Yingcheng Formation. Sha Hezi Formation and the 2nd Member of the Yingcheng Formation were source rock strata, while the rest were volcanic rocks. By aiming at discussing interactions of volcanic fluids represented by volcanic rocks and interbedded source rocks, a series of hydrocarbon generation simulated experiment were carried out on the Yingcheng Formation source rocks, and the product generated after the experiments were analyzed as well.Two groups of simulated experiments were carried out in this paper; one was the source rocks hydrocarbon generating simulation experiment under fluid system (source rocks with adding volcanic fluids), the other was under drying system (source rocks without adding volcanic fluids). By comparing the yield of gas produced under the two grouped experiments combined with the gas component, the stable carbon isotope ratios of gas products and the generated liquid hydrocarbons, some recognition were concluded:①The volcanic fluid has effect on the gas yield, compared with drying system,there is a critical temperature point between 350℃and 450℃,when the temperature is lower than the critical temperature point,the gas yield is increasing, when the temperature is greater than the critical temperature point,the gas yield is decreasing.②Volcanic fluid prompted the generation of CO2 of the gas component, but inhibited the production of H2 and C1-C5 series light hydrocarbon.③Based on the stable carbon isotope ratio of generated CO2, the effect of volcanic fluid resulted in a negative excursion of the CO2 carbon isotope ratio.④Under the temperature range of simulated experiment, more liquid hydrocarbons were produced under the action of volcanic fluids.⑤G C and GC-MS analysis of the liquid hydrocarbons demonstrated that there is no obvious difference between the composition of liquid hydrocarbons produced under the two different simulated systems, underlying that the existence of volcanic fluids has no effect on the composition of the liquid hydrocarbon product.