Zhao Wenzhi

Zhao Wenzhi (Chinese: 赵文智, last name Zhao, born August 1958) is a Chinese petroleum geologist and explorer who has made remarkable contributions to the theories and discoveries of lithology-related hydrocarbon accumulations with large scale, natural gas relaying generation in high to over mature geothermal evolutional stage, Jurassic coal measure-derived hydrocarbon reservoirs, and sag-wide oil-bearing distribution, etc. He is an academician of the Chinese Academy of Engineering. He is currently the President of PetroChina Research Institute of Petroleum Exploration and Development (RIPED), and Deputy General Manager of PetroChina Exploration & Production Company. Zhao was voted one of China’s top 35 scientists in 2007 and ranked 14.

Profile

After having received his BS degree in Petroleum Geology from Northwestern University in Xi’an, 1982.Zhao went to Research Institute of Petroleum Exploration & Development (RIPED), where he completed his MS in 1984. He joined the faculty of the institute immediately afterwards. Zhao gained his PhD in Mineral Resource Prospecting and Exploration from RIPED in 2003. Zhao has been engaged in the research on oil and gas accumulation & distribution theory as well as exploration practice in onshore China for nearly 30 years. He has accumulated rich experience and knowledge in hydrocarbon generation, accumulation and distribution in the superimposed petroliferous basins, petroleum resources evaluation and play assessments, petroleum system analysis and strategic study on the future oil & gas supply and demand in China. His first major contribution, made in the late 1980s, was about the distribution patterns of Jurassic coal measure-derived hydrocarbon reservoirs in Turpan-Hami basin in NW China, which help to propose the favorable exploration regions and targets that led to the breakthrough of commercial oil flow from the Jurassic interval after nearly 30 years of exploration stop. Afterwards, he put forth the new geological theories like natural gas relaying generation, sag-wide oil-bearing distribution and lithology-related reservoirs with large-scale, etc. These concepts have been widely applied to the exploration practice in the past 10 years, which made great contributions in discovering several large oil/gas fields particularly in the hydrocarbon-rich source kitchen areas of Ordos, Songliao, Tarim and Sichuan basins in onshore China. Zhao has published over 100 technical papers both at home and abroad so far. He is also the first author of 6 academic books. Zhao has received several honorable and scientific & technological awards for his contributions, among them the Prize for Outstanding Young Scientists of Sun Yueqi Foundation (1994), the Golden Hammer Medal of China Geological Society (1994), National Early Career Awards for Scientists and Engineers (1998), Li Siguang Geological Science Medal (2003), the First Prize of National Scientific and Technological Progress Award (2007), the Prize for Energy Technological Achievements of Sun Yue-qi Foundation (2007), the Prize for Scientific and Technological Innovation of Ho Leung Ho Lee Foundation (2009). Zhao is currently holding as the chairperson of the Petroleum Geology Committee of Chinese Petroleum Society; member of China National Committee for ICGP (UNESCO International Geological Correlation Program) and adjunct professor of Northwestern University, China University of Petroleum, and Jilin University. He served two terms (2001–2011) as chief scientist of natural gas project of the State Basic Research Program of China (also called 973 Program).

Scientific Contributions

Lithology-related oil/gas reservoir with large-scale theory

Zhao organized the study of lithology-related oil/gas accumulation theory and evaluation technology from 1997 to 2005, focusing on hydrocarbon accumulation with large scale in the flat and tectonic low areas in faulted sag-type, depression-type and foreland-type sedimentary basins. He has established the theory of large-scale lithology-related oil/gas accumulations with medium-low abundance, which helps to expand the exploration activity from the limited structural highs to the wide-ranged depressions. As a result, abundant oil and gas reserves have been discovered in the areas which were formerly considered unfavorable for oil/gas accumulations. Zhao has paid long effort for years on the research of possibility of oil/gas pool formation in the flat and tectonic low areas where are commonly occupied by the hydrocarbon-rich source kitchens in onshore non-marine sedimentary basins of China. After careful investigations of the petroleum geological conditions of several oil wells in the synclinal low area of Songliao basin from 1997 to 2000, he proposed sag-wide oil-bearing theory in hydrocarbon-rich sags and depressions. He also pointed out that geologists should think outside of the box, expanding the exploration activity from the traditional structural plays to the whole sag and depression. These opinions were widely accepted by the executive exploration organizers at CNPC domestic business units, which made great contributions in discovering several large oil-gas fields in the hydrocarbon-rich depression areas of Ordos, Songliao, Tarim and Sichuan basins. Since 2003, Zhao was appointed as chief vice-Project Manager to organize the research project of study and practice of "lithology-related large scale oil/gas accumulation theory", focusing on research of oil and gas accumulations with large-scale particularly in the flat and tectonic low areas of depression-type sedimentary basins. He firstly pointed out that the deltaic and fluvial sandbodies can reach the depo-center areas with large distributional area during certain stages in open lacustrine sedimentary basins, where the source rock and reservoir often form sandwich-type association in big scale. Such opinion broke the previous understandings and provided a theoretical basis for carrying out exploration work in areas of previously considered poor prospects for oil and gas accumulation, and has made great contributions in discovering large oil and gas reserves in source rock-occupied synclinal areas of several onshore sedimentary basins in China. At the same time, he has also done some fundamental research on the mechanism of oil/gas accumulations in the flat and tectonic low areas where the buoyancy induced by oil or gas/water contact is poorly weak. Hence, he confirmed as early as in 1995–1997 that the large oil/gas accumulations might possibly exist in the synclinal areas where the association of source rock and reservoir is well developed. He also organized to develop the key assessment technologies on lithology-related reservoirs which cover two-level evaluations including play and trap. This technology package has definitely played an important role in discovering large scale oil and gas reserves in synclinal areas in recent years. To recognize his contributions in this field, Zhao was awarded with the first-class prize of State Scientific and Technological Progress Award in 2007.

Natural Gas Relaying Generation in High to Over –mature Stage

Zhao has paid long study on the formation and exploration of natural gas in the high to over mature geo-thermal evolutional region, which resulted in the generation of natural gas relaying generation theory. This theory paved the way to the gas exploration in the strata which were previously thought not worth for further exploration, By using this theory, several key exploration wells were drilled separately in Tarim and Sichuan Paleozoic interval, which have led to significant discoveries of large natural gas accumulation, like well Gucheng-6 obtaining high flow of natural gas from over mature Ordovician carbonate in eastern Tarim and well Gaoshi-1 getting huge accumulation in the over mature Sinian to Cambrian carbonate in central Sichuan. Since 2001, as the chief scientist of National 973 natural gas fundamental research program, Zhao conducted research on the gas generation and accumulation which was derived from the dispersed liquid hydrocarbons retained in source rocks. He designed and did a series of kinetic simulation experiments of hydrocarbon generation and expulsion, focused on the quantity of dispersed liquid hydrocarbons retained in the source rocks, major timing of liquid HC cracking, exploration potential and identification of natural gas in high to over mature stage. Based on the results, it is found that the dispersed liquid hydrocarbons retained in the source rocks can reach 40% to 60% of the total liquid HC generation, and could generate a large amount of gas during high to over mature stage （Ro：1.6%~3.2%）and therefore, form considerable scale natural gas reservoirs. The Paleozoic of Tarim and Sichuan basins have reached high to over thermal evolution stage (Ro: 3.0% ~ 4.0%), and no potential for gas discovery is believed to exist, if using the previous knowledge. Due to the emergence of new natural gas relaying generation model, the exploration efforts in the over mature Paleozoic intervals were intensified. So, a number of natural gas reservoirs have been discovered and isolated in Lungudong, Tazhong and eastern Tarim areas. A super-giant gas field with the total GGIP greater than one trillion cubic meters has been discovered in the Sinian-Cambrian carbonate in central Sichuan basin, which has been verified by geochemical correlation to come from the cracking of liquid hydrocarbon in high to over mature stage. This theory makes a great contribution to speed up the natural gas exploration and low carbon economy development in China. Natural gas relaying generation theory was regarded as one of the significant achievements, since the state science and technology plan on natural gas research project conducted nearly 30 years ago. Hence, he was honorably awarded with Second Prize of National Scientific and Technological Progress in 2008.

Jurassic coal measure-derived hydrocarbon reservoir theory

As one of the long-time researchers on Jurassic coal measure-derived hydrocarbon reservoirs in NW China, Zhao took Turpan-Hami basin as the breakthrough point to summarize the basic petroleum geological conditions and distributional regularity of oil/gas accumulations. After doing a comprehensive research and assessment on the favorable plays and drilling targets in 1987, he took the responsibility to write the pre-drilling research report to proof the location of drilling the first scientific exploration well (SEW) in onshore China, and he suggested the Shanshan local structural high is the best place to drill a wildcat in Turpan-Hami basin. In 1989, the well Taican-1 got the commercial oil flow of 25.9 cubic meters per day in the Jurassic interval, which was the first breakthrough, since the exploration activity had long been stopped in 1950s-1960s. Up to date, Turpan-Hami basin has established a medium oil/gas production unit under PetroChina management with the annual production reaching 3 million tons of oil equivalents. Since the discovery of Shanshan oil field, Zhao had been keeping research on the whole Jurassic strata in NW China in particular, and summarized the favorable conditions for coal measure-derived oil/gas accumulations as the followings: ①the Jurassic prototype basin must exist to accumulate abundant and good-quality source kitchen with coal beds and coaly seams dominantly developed where both the oil-prone and gas-prone maceral materials are rich accumulated; ②the successive basin are moderately developed sitting on the Jurassic prototype basin, which is necessary not only to keep the source rock in an appropriate maturation, but also to maintain the reservoir having certain amount of porosity; ③the good association of source rock-reservoir-cap rock are well reserved for late occurrence of oil/gas migration and accumulation and ④certain degree of tectonic compression is needed to push the oil expulsing in quantity from the coal measure source rocks which have strong absorption on the oil and gas. Based on his research, Zhao proposed six favorable regions for doing further exploration in 1995 in NW China, which have been proved by a number of exploration wells and discoveries to be the best regions where traps the major oil/gas accumulations of Jurassic and Jurassic source rock-related in NW China. According to statistics, so far the proved oil and gas reserves discovered in Zhao’s predicted six zones have exceeded 1.5 billion tons of oil equivalents, which has yearly provided more than 15 million tons of oil equivalents. It is also confirmed that there is no oil and gas reserve output outside these 6 zones. Due to his contribution in pushing exploration of Jurassic coal measure-derived oil/gas reservoirs, he won the First Prize of provincial-level Award (CNPC) in 1995, and an award for significant discoveries of Oil & Gas Fields from CNPC in 1997.

“Sag-wide Oil-Bearing Theory ”in the Hydrocarbon-rich Depression

"Sag-wide Oil-Bearing Theory" in the hydrocarbon-rich depression was the conclusion drew by Zhao and his research team in 2004, after he paid long research of nearly 10 years. This theory is the extension of the “Source kitchen Control Accumulation” and “Composite Plays of Hydrocarbon Accumulations” conducted by previous Chinese geologists in the 1970s-1980s. Sag-wide oil-bearing theory means that there is everywhere for oil/gas accumulation occurrence in the source-rich sag and depression, due to the frequent contact of reservoir and source rock, and formation of lithological traps as well. This theory emphasizes that the following conditions are necessary for sag-wide oil-bearing pattern formation: ①existence and widespread distribution of good quality source rocks; ②large-scale sandwich-type association of source rock interbedding with reservoirs;③suitable geothermal evolution leading to huge amount of hydrocarbon generation and expulsion to provide sufficient source for accumulation in all porous sandbodies. Based on his research, the major mechanism for the sag-wide oil-bearing distribution in the flat and tectonic low areas is: ①the pressure difference between source and reservoir caused by the oil/gas generation and provide the major force to drive the hydrocarbon moving in the permeability-low reservoirs;②the density difference of hydrocarbons between source beds and reservoirs, which help oil/gas moving quantitatively in the diffusive way from the source to the reservoir and ③the strong heterogeneity and discontinuity of reservoirs, which help to reduce oil/gas’s energy escaping from the traps and keep the accumulation stable even in the poor sealing condition environment. The major contribution of this theory to the further and future exploration activity is to expand the exploration play from previous local limited structural highs to the whole sags or depressions where are occupied by good-quality source rocks. It is revealed by Dr. Zhao that the formation of lithology-related reservoirs is mainly controlled by three “surfaces”, e.g. the maximum lake flooding surface, unconformities and faulted surface. And most of the hydrocarbon accumulations are dominantly distributed in “five zones”, e.g. favorable sedimentary faces zone, lithological or stratigraphic pinch out belts, slope-breaks at syn-depositional stages, fracture zones and secondary pore zones. The theory also pointed out that further exploration in the hydrocarbon-rich sags or depressions should cover the whole sags and depressions and focus on searching for sweet points.

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External links

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