Experimental study on late gas generation characteristics of the Middle Devonian sapropelic source rocks of in Northwestern Sichuan Basin

被引：0
|
作者：
Tian H. [1 ,2 ]
Wu Z. [1 ]
Gai H. [1 ,2 ]
Wang X. [1 ,2 ]
机构：
[1] State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, CAS, Guangdong, Guangzhou
[2] Center for Excellence in Deep Earth Science, CAS, Guangdong, Guangzhou
来源：
Oil and Gas Geology | 2023年 / 44卷 / 01期
关键词：
deep natural gas; gas from kerogen cracking; late gas generation; methane carbon isotope; Middle Devonian; Northwestern Sichuan Basin; sapropelic source rock;
D O I：
10.11743/ogg20230104
中图分类号：
学科分类号：
摘要：
The Paleozoic source rocks in southern China contain mainly Type Ⅰ - Ⅱ kerogen and are currently over-mature with vitrinite reflectance（Ro）greater than 2. 0 %. Accurate evaluation of the gas generation potential of Type ⅠⅡ kerogen after oil generation and expulsion and geochemical characteristics of over-mature gases are of great significance to natural gas exploration of deep and ultra-deep Paleozoic gas pools in southern China. In view of this，the mature Devonian source rock samples（Ro≈1. 1 %）collected from the Guanwushan Formation in Northwestern Sichuan Basin are applied for gold tube pyrolysis experiments，and the gas generation potential of Type Ⅰ-Ⅱ kerogen at the high-to-over mature stage and the geochemical characteristics of over-mature gas generated are investigated in combination with existing documents. The results show that the residual oil content of the studied samples is 140 mg/gTOC and has a gas generation potential of 220 mL/gTOC at present，indicating high gas-generation potential. Furthermore，the amount of gas from kerogen cracking is at least 140 mL/gTOC and that of gas from residual oil cracking is at best 80 mL/gTOC，indicating that kerogen-cracking gas is the main source of late gas generated from the sapropelic source rocks under high oil expulsion efficiency. Meanwhile，the geochemical characteristics of the late gases generated from the sapropelic source rocks are obviously affected by oil expulsion efficiency. For example，the dryness coefficient of the gases is high，and the methane carbon isotope grows heavier rapidly with increasing methane yield. At Ro≈3. 50 %，the carbon isotope of methane is close to that of the original kerogen（with a mere carbon isotopic fractionation difference of 0. 5 %）. The results obtained above will be of scientific basis to the evaluation of natural gas exploration potential and the identification of natural gas sources in the deep and ultra-deep Paleozoic reservoirs in southern China. © 2023 Editorial Department of Oil and Gas Geology. All rights reserved.
引用
收藏
页码：46 / 54
页数：8
相关论文
共 55 条
  • [1] Jinxing DAI, Yan SONG, Houfu ZHANG, Main factors controlling the foundation of medium-giant gas fields in China［J］, Science in China Series D：Earth Sciences, 40, 1, pp. 1-10, (1997)
  • [2] GALIMOV E M., Sources and mechanisms of formation of gaseous hydrocarbons in sedimentary rocks［J］, Chemical Geology, 71, 1/3, pp. 77-95, (1988)
  • [3] HILL R J，, RUBLE T E，, Et al., Unconventional shale-gas systems：The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-as assessment［J］, AAPG Bulletin, 91, 4, pp. 475-499, (2007)
  • [4] BEHAR F, VANDENBROUCKE M, TEERMANN S C，, Et al., Experimental simulation of gas generation from coals and a marine kerogen［J］, Chemical Geology, 126, 3, pp. 247-260, (1995)
  • [5] CORVI P J., Simple kinetic models of petroleum formation. Part Ⅲ ：Modelling an open system［J］, Marine and Petroleum Geology, 12, 4, pp. 417-452, (1995)
  • [6] DAI Jinxing, WEI Yanzhao, ZHAO Jingzhou, Important role of the formation of gas accumulations in the late stage in the formation of large gas fields［J］, Geology in China, 30, 1, pp. 10-19, (2003)
  • [7] DAI Jinxing, ZOU Caineng, TAO Shizhen, Et al., Formation conditions and main controlling factors of large gas fields in China ［J］, Natural Gas Geoscience, 18, 4, pp. 473-484, (2007)
  • [8] MA Yongsheng, GUO Xusheng, GUO Tonglou, Et al., Discovery of the large-scale Puguang gas field in the Sichuan Basin and its enlightenment for hydrocarbon prospecting［J］, Geological Review, 51, 4, pp. 477-480, (2005)
  • [9] MA Yongsheng, CAI Xunyu, ZHAO Peirong, Et al., Distribution and further exploration of the large-medium sized gas fields in Sichuan Basin［J］, Acta Petrolei Sinica, 31, 3, pp. 347-354, (2010)
  • [10] JARVIE D M., Shale resource systems for oil and gas：Part 2—shale-oil resource systems, Shale Reservoirs—Giant Resources for the 21st Century, pp. 89-119, (2012)
123456