The Effects of High Pressure on Oil-to-Gas Cracking during LaboratorySimulation Experiments Chen Zhonghong,* Ma Zunjin, Zha Min, Sha Xiaoy, Zhang Shouchun and BaoYoushu. Journal of Petroleum Geology, Vol. 37(2), April 2014, pp 143-162. The effects of high pressures on the yield and kinetics of gas generatedby the cracking of crude oil were investigated in laboratory simulationexperiments. Samples of a low maturity nonmarine oil were recovered from thePaleogene Shahejie Formation in the Dongying depression, Bohai Bay Basin,eastern China. The oils were cracked to gas under different pressure and temperatureconditions in an autoclave. Initial temperatures of 300 °C were increased to650 °C at rates of either 30 or 100 °C/h. Reaction products were analysed atthe end of each 50 °C temperature increase. Pressure conditions were either 0.1MPa (i.e. atmospheric) or 20 MPa. Results show that high pressures inhibit ordelay oil to gas cracking and retard the initiation of the cracking process.The temperature at which oil was cracked and the activation energy of theformation of C1–5 hydrocarbons increased under high pressure conditions,demonstrating the effects of pressure on the kinetics of the oil to gascracking process. High pressures and high temperatures inhibited the conversion of C2-55 hydrocarbons to methane during secondary cracking. In addition, highpressures retarded the generation of N2, H2 and CO during cracking of oil. Thepresence of water increased the yields of total cracked gas, C2–5 hydrocarbonsand CO2 in high-pressure conditions. The simulation results show that CO2 and C2–5 hydrocarbons have similar yields during oil-to-gas cracking. Using the kinetic parameters determined from the laboratory experiments,the yield and production rate of gas generated during the cracking of oil fromMember 4 of the Paleogene Shahejie Formation in the Minfeng-Lijin sag (Dongyingdepression) were calculated. The results indicate that only limited volumes of natural gas in this area werederived from the cracking of oil, and that most of the gas was derived from thethermal decomposition of kerogen.
牛 38 井湖相烃源岩镜质体反射率负异常与有机组分含量相关性 陈中红 , 等。西安石油大学学报(自然科学版), 2009 , 24 ( 1 ): 29-34. 对东营凹陷牛 38 井古近系沙河街组有机碳富集的沙三中、下层段烃源岩(有机碳含量平均值分别达到 2.0% 、 4.0% )进行了大量样品的分析测试及研究,发现该层段烃源岩存在明显的 R o 抑制现象(负异常)。研究结果表明, R o 异常值与壳质组含量、腐泥组含量呈正向线性统计关系,而与镜质组含量呈负向线性统计关系,与惰质组关系不明显。在剖面分布上, R o 抑制层段对应较高含量的壳质组与腐泥组。 H 含量及 H/O 比呈负向线性统计关系,与 O 含量呈正向线性统计关系。单从有机成因角度分析,高含量富氢的壳质组、腐泥组是 R o 出现负异常的主要原因。针对该盆地的深层油气勘探应考虑到可能出现的 R o 负异常现象。 关键词: 东营凹陷 烃源岩 R o 异常 成熟度 镜质组反射率 Relationship between the SUPPRESSION OF VITRINITE REFLECTANCE OF LACUSTRINE SOURCE ROCKS from NIU-38 WELL in Dongying sag AND the contents of organic components Chen Zhonghong, etc. Journal oc Xian Shiyou University, 2009 , 24 ( 1 ): 29-34. (China University of Petroleum, Dongying, Shandong, 257061) The member 3 of Shahejie Formation, main source rock section of Well Niu-38 is closely surveyed and analyzed to investigate the obvious suppression of vitrinite reflectance ( R o ) of the lacustrine source rocks. The abnormal value of R o is from 0.01%~0.25%. The stat. show positive linear relation between the abnormal value of R o and exitinite and sapropelinite contents, and the stat. show negative linear relation between value of R o and hydrogen content, H/O, and positive linear relation between value of R o and oxygen content. The section of suppression of R o is corresponding to high contents of exitinite and sapropelinite. The results shows: high contents of hydrogen-rich exitinite and sapropelinite is the controlling factor for the suppression of vitrinite reflectance, and the suppression appeared when liptinite content is over 40% (hydrogen content is about 2%).