Image Descripion: Chenglin Liu was investigating outcrop oil shows in the Colorado State, USA in October 2015.

Primary research in hydrocarbon generation is yielding new insights into the natural gas geochemical characteristics of conventional and unconventional reservoirs, along with discoveries relating to the geomechanical processes. Welcome to an interview with Chenglin Liu, China University of Petroleum-Beijing, who discusses enlightening new findings regarding the relationship between salinity and hydrocarbon geochemical characteristics.

What is your name and your background in geology?

My name is Chenglin Liu, and I have been working in petroleum geology for 22 years. I received my B.A. degree (1994) in petroleum geosciences and my Ph.D. (2004) in mineralogy, petrology, and mineral deposit geology from the China University of Petroleum-Beijing. From September 2008 to September 2009, I conducted postdoctoral research on petroleum resource assessment methodologies with the U.S. Geological Survey. In July 1994, I joined the Langfang Branch, Research Institute of Petroleum Exploration and Development, China National Petroleum Corporation, where I worked as a natural gas research geologist for 10 years. Since July 2004, I have been Associate Professor, Professor and Director of the Petroleum Geology Faculty of Geoscience College at the China University of Petroleum-Beijing, where I am continuing my petroleum geology research and teaching. From April 2012 to April 2016, I also worked with the Institute of Geomechanics, Chinese Academy of Geological Sciences, as a research geologist. Since March 2003, I have been conducting China national petroleum assessments with the Strategic Research Center of Oil and Gas Resources, Ministry of Land and Resources.

What are some of your current research interests?

My current research interests cover conventional and unconventional petroleum accumulation mechanism. I am studying natural gas geochemical characteristics and their origins in saline lacustrine source rocks. In addition, I am conducting research on shale oil accumulation mechanisms and their spatial distributions and the bitumen evolution process and its link with metal elements.

What do you believe are some of the most important trends in petroleum technology of the last 2 - 5 years?

In my research domain, I believe that the most important trends in petroleum technology include

1. hydrocarbon generation simulations in closed and open systems under various temperature, pressure, and medium conditions, which are key to studying hydrocarbon generation potential in saline lakes, deep and superdeep overpressure environments, and environments rich in metals and other elements
2. fine sedimentary rock reservoir observations and petroleum accumulation simulations at micrometer-nanometer scales, which are key to studying tight oil and gas generation, migration, accumulation, and preservation mechanisms
3. unconventional petroleum resource assessment methodologies and software systems, which are key to estimating shale oil and other unconventional petroleum resources and their distribution with higher confidence

What do you believe are some of the "must-know" geoscience knowledge breakthroughs of the last 10 years?

Knowledge in the geosciences has made rapid progress over the last 10 years. In my opinion, there have been five important geoscientific breakthroughs, including

1. the reconstruction of palaeocontinent and palaeogeography during the supercontinent evolution, which influenced the global petroleum resource potential and distribution predictions
2. palaeontology evolution, carbon recycling and organic-rich source rock formation mechanisms, which stimulated more potential petroliferous area discoveries
3. shale oil and gas formation and distribution mechanisms, which promoted global shale oil and gas exploration and development
4. deep ocean petroleum accumulation and distribution mechanisms, which quickened the world's ocean petroleum exploration and exploitation
5. Paleozoic offshore carbonate natural gas accumulation mechanisms, which proceeded giant gas field discoveries in China and other countries

Please describe some of the work that you and the people you direct have been involved in.

Currently my research team is focusing on the link between salinity and hydrocarbon geochemical characteristics. We have found that most natural gas from the Paleogene and Neogene saline lacustrine facies has higher dry coefficients and carbon isotopes of methane, ethane and propane in the western Qaidam Basin in NW China. It is inferred that these gas geochemical characteristics are related to the salt minerals and salinity in the Paleogene and Neogene formations. There are two unsolved issues:

1. How does salinity affect the organic matter richness, type and thermal maturity?
2. What is the natural gas generation mechanism of the source rocks under different chloride concentrations?

My research team has been supported by the China National Natural Science Fund Project (41272159) of Chloride Concentration's Effects on the Composition of Natural Gas Generated from Source Rocks from 2013 to 2016. Based on field geological investigations, sample tests, and simulation experiments of the influence of chloride concentration on the gas generation process of the source rocks, we believe that various biological types, organic productivity, and preservation conditions formed a three-interval model of organic matter enrichment during the Paleogene and Neogene saline lake development, and that the thermal maturities of the source rocks are also influenced by the formation's salinity, which increases the apparent activation energy and reduces the hydrocarbon generation rate in the western Qaidam Basin. Furthermore, supported by the China National Natural Science Fund Project (41572099) of Paragenesis Mechanism of Anthraxolite and Vanadium from 2016 to 2019, we are working on the genesis and distribution relationship between bitumen and metal elements. In addition, my team has been working on shale oil enrichment and distribution in the Cretaceous Qingshankou Formation, Songliao Basin, NW China.

Please describe some of your plans for the future.

My future plans include four goals:

1. trying to improve the teaching outcomes in the Oil and Gas Field Exploration course for undergraduates and the Petroleum Exploration Project and Assessment course for graduate students and guiding my graduate students to complete their dissertations
2. finishing our study of the effects of chloride concentration on the composition of natural gas generated from source rocks by the end of this year
3. conducting research on the paragenesis mechanism of anthraxolite and vanadium from 2016 to 2019, including the lower Ordovician anthraxolite geological conditions in the northern Qaidam Basin, hydrocarbon generation and vanadium mineral evolution simulation under different temperature, pressure and medium conditions, and the paragenesis model and main controlling factors of anthraxolite and vanadium occurrence; and
4. applying for other scientific projects and writing more papers and books related to my research interests

Are there any articles or books that you would like to recommend?

I would like to recommend "Evaporites: Sediments, Resources and Hydrocarbons" by Professor John K. Warren, who offered a comprehensive synthesis of the low temperature (sedimentary) realm of evaporate evolution. It is an excellent guidebook for saline lacustrine mineral and petroleum geology research. In addition, I would recommend "Petroleum Formation and Occurrence" by Professor Bernard Tissot and Pofessor Dietrich Welte, which is a classic textbook for graduates and a classic guide for petroleum geologists and geochemists. Other suggested articles are as follows:

Ma, Y., Zhong, N.N., Li, D.H., et al., 2015: Organic matter/clay mineral intergranular pores in the Lower Cambrian Lujiaping Shale in the north-eastern part of the upper Yangtze area, China: A possible microscopic mechanism for gas preservation. International Journal of Coal Geology, 137: 38-54.

Liu, C.L., Li, H.H., Zhang, X., et al., 2016: Geochemical characteristics of the Paleogene and Neogene saline lacustrine source rocks in the Western Qaidam Basin, Northwestern China. Energy & Fuels, 30: 4537−4549.

Liu, C.L., Wang, Z.Z., Che, C.C., et al., 2014: The reserve-growth model of oil fields in the Bohai Bay basin, China. AAPG Bulletin, 2014, 98 (12): 2611–2628.

Liu, C.L., Che, C.C., Zhu, J., et al., 2012: Comparison of petroleum resources assessments of China by the U.S. Geological Survey and China's National Petroleum Assessment. AAPG Bulletin, 96(8): 1415–1427.

Liu, C.L., Charpentier, R.R., Jin, S., 2011: Comparison of two methods used to model shape parameters of Pareto distributions. Mathematical Geosciences, 43(7): 847-859.