Innovators in Geosciences Series

Toward a Better Understanding of Micro and Nano-Pores and Geomechanics: Interview with Wen Zhou

Published
American Association of Petroleum Geologists (AAPG)

The dynamics of fluid behavior and structural movement on the nano-scale can be complicated and not always what was expected. New research that analyzes the well information and cores using new techniques and technologies is yielding important and useful results. Welcome to an interview with Wen Zhou, Chengdu University of Technology, who discusses recent research findings.

What is your name and your background in geology?

Figure 1.Evaluation of crack or fracture development characteristics in reverse faults zone of Ordos Basin: the figure shows the thickness of stratum and the distance to fault-zone are two factors limited the degree of development of cracks.
Figure 1.Evaluation of crack or fracture development characteristics in reverse faults zone of Ordos Basin: the figure shows the thickness of stratum and the distance to fault-zone are two factors limited the degree of development of cracks.
My name is Wen Zhou. From Sep 1979 to Aug 1983, I pursued my bachelor degree in Petroleum Geology from Department of Petroleum, Chengdu College of Geology. From Sep 1983 to Aug 2004, I worked as an assistant professor, lecture, and associated professor in Department of Petroleum, Chengdu College of Geology, and mainly engaged in research and teaching of Oil and Gas Field Subsurface Geology. I earned my Ph.D. degree in Oil-Gas Field Development Engineering from Sep 2002 to Aug 2004 in College of Energy Resources, Chengdu University of Technology.

From Sep 2004 to current, I have been the professor and academic leader in College of Energy Resources, Chengdu University of Technology, and mainly engaged in teaching and research of Oil and Gas Field Development Geology, Oil and Gas Field Development Engineering. Since Oct 2010, I have served as the Vice Director of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Executive Vice Director of the Office in Chengdu University of Technology.

What are some of your current research interests?

Figure 2.The channel sand body dimension and parameters optimization (including completion, stimulation, production) of SF23-1HF horizontal well from Jurassic Shazu tight sand formation, Xinchang area, Western Sichuan: according to the detailed dimension description of channel sand body and the stress orientation, the horizontal well drilling parameters (horizontal length and orientation) and multi-stage stimulation parameters (stage number, fracture spacing) were optimized, and reasonable production data were proposed, which almost matched with the field production.
Figure 2.The channel sand body dimension and parameters optimization (including completion, stimulation, production) of SF23-1HF horizontal well from Jurassic Shazu tight sand formation, Xinchang area, Western Sichuan: according to the detailed dimension description of channel sand body and the stress orientation, the horizontal well drilling parameters (horizontal length and orientation) and multi-stage stimulation parameters (stage number, fracture spacing) were optimized, and reasonable production data were proposed, which almost matched with the field production.
My research interests are in the area of evaluation theory and technology applied to unconventional oil gas reservoirs, including:

  1. Micro-pores characteristics of shale reservoirs
  2. Rock mechanics characteristics of shale reservoirs
  3. Engineering geology of shale reservoirs
What do you believe are some of the most important trends in petroleum technology of the last 2 - 5 years?
  1. The technologies based on rock mechanics and in-situ stress analysis applied to fracture prediction and description, the rock failure theory of shale, and microseismic fracture detection.
  2. The technologies based on tight reservoirs geometry and dimension assessment (including sand body configuration and etc.) applied to horizontal well development and deployment, completion parameters optimization and stimulation parameters optimization.
  3. Data mining techniques applied on horizontal well parameters optimization, production analysis, fracture-fluid flowback analysis, and sweet-spot identification.
  4. The shale pore structure characterization based on micro-pore characterization, digital core analysis, and 3D slices techniques, the fluid distribution characterization in shale reservoir micro-pore system, and the evaluation of shale gas oil bearing-property.
  5. The issue related to fluid flow mechanism in shale reservoir micro-pore system (including micro to Nano scale pore system, microfracture, and stress state), the issue related to fracture, stress, fluid-solid coupling flow mechanisms (geology-physics-mathematic model), and the issue related to micro-particles flow mechanisms in porous medium (physics-mathematic model).

Figure 3.Fluid distribution pattern in micro-pores of high (over) mature shale reservoir (without micro cracks): according to the characteristic of micro pores in shale (size and distribution of inorganic pore and organic pore) and the results of micro-scale tracer testing, rock wettability test and thermal evolution test of high maturity organic matter, the gas and water distribution pattern of shale in micro-scale porous system was established as: the organic pores are the micro ‘gas source’ in rocks, which are gas-bearing pores; the natural gas in organic pores was driven into the inorganic pores by overpressure through multiple paths as a ‘network’; the inorganic pores along the ‘paths’ are water wet, which are the gas-bearing pores with bound water; beside the flow ‘paths’ are water-bearing inorganic pores; the water content increases from organic matter to flow ‘paths’ to outside micro pores.
Figure 3.Fluid distribution pattern in micro-pores of high (over) mature shale reservoir (without micro cracks): according to the characteristic of micro pores in shale (size and distribution of inorganic pore and organic pore) and the results of micro-scale tracer testing, rock wettability test and thermal evolution test of high maturity organic matter, the gas and water distribution pattern of shale in micro-scale porous system was established as: the organic pores are the micro ‘gas source’ in rocks, which are gas-bearing pores; the natural gas in organic pores was driven into the inorganic pores by overpressure through multiple paths as a ‘network’; the inorganic pores along the ‘paths’ are water wet, which are the gas-bearing pores with bound water; beside the flow ‘paths’ are water-bearing inorganic pores; the water content increases from organic matter to flow ‘paths’ to outside micro pores.

What do you believe are some of the "must-know" geoscience knowledge breakthroughs of the last 10 years?
  1. Advances in microbial rock research, including the characteristics of 30-40 million years microbial rock, and issues related to earth geology, environment, and life; oil and gas reservoirs in microbial rock
  2. Hydrocarbon resources assessment of fine grain sedimentary rock (shale)
  3. Research progresses in deepwater natural gas hydrate (cause of formation, field investigation, and distribution evaluation)
  4. Research progresses in deep oil gas resources generation theory and evaluation (depth over 6000 meters)
Please describe some of the work that you and the people you direct have been involved in.

I listed several major works here: 1998-2007, "Evaluation Methods of Existing Stress Field Characteristics in Oil Gas Reservoirs"; 2005-2010, "Horizontal Well Parameters Optimization and Post-frac Evaluation of Tight Sand Formation in Western Sichuan Basin"; 2009-2014, "Evaluation Techniques of Continental Shale Oil and Shale Gas Reservoirs"; 2012-2016, "Shale gas Reservoir Characterization and Evaluation Techniques Study" (Professor Hu Qinhong from University of Texas at Arlington participate in the study).

I have two research teams now:

  1. Shale oil and gas reservoirs research team, team members include Yang Yu (associated professor), Deng Hucheng (associated professor), Xie Runcheng(associated professor), Liu Hongbo(associated professor), and Chen Wenling(Lecture).
  2. Carbonate oil and gas reservoirs research team, team members include Chen Yicai (associated professor), Wang Xinjian (associated professor), Meng Xianghao(lecture), Guo Ming(lecture).
Please describe some of your plans for the future.

Figure 4.The overlap map combined lithology and maximum main stress of TX53 single layer of XinChang Formation in Western Sichuan Basin: In the simulation of finite element stress field, the lithology distribution of the simulation layer (sandstone, mudstone distribution), fault zone, and fracture zone are considered (The simulation of stress field in fracture zone are significant advances been made). The horizontal maximum principal stress distribution is controlled by lithologic bodies (sand body boundary), fault zone, fracture zone distribution and their combination.
Figure 4.The overlap map combined lithology and maximum main stress of TX53 single layer of XinChang Formation in Western Sichuan Basin: In the simulation of finite element stress field, the lithology distribution of the simulation layer (sandstone, mudstone distribution), fault zone, and fracture zone are considered (The simulation of stress field in fracture zone are significant advances been made). The horizontal maximum principal stress distribution is controlled by lithologic bodies (sand body boundary), fault zone, fracture zone distribution and their combination.
From 2016 to 2020, I have two major research projects including:

  1. "Characterization and Evaluation Techniques of High Mature Marine Shale Gas Reservoir in China (Sichuan Basin Silurian Longmaxi Formation, Cambrian Niutitang Organic Rich Shale Formation)". This project is focused on:
    1. High mature shale micro-pore system characterization (type, size, cause of formation etc.), especially the generation and features of organic pore in different evolution stage, and quantitative characterization methods for micro porous medium
    2. High mature shale micro-pore structure characterization (by adsorption method, high pressure Hg injection method and digital core technique etc.) and characterization techniques (capillary pressure curve, micro pore-throat diameter distribution, typical pore structure parameters, shale reservoir classified based on pore structure parameter)
    3. Study on micro-scale fluid distribution characteristics of shale porous system, including the micro-pore model establishment based on quantitative parameters, tracer techniques, fluid distribution model and molecular model in micro pores
    4. Natural fracture characterization and evaluation based on rock mechanics parameters analysis (logging identification, distribution evaluation); Evaluation of shale rock brittleness and stress field; Mechanism of fracture generation and propagation; Fracture network connection and coupling model.
  2. "Characterization and Evaluation of Deep Carbonate Hydrocarbon Accumulation in Petroleum Basin in Western China". This project is focused on:
    1. Characteristics and evaluation of hydrocarbon generation potential of deep source rocks in basins (Mainly refers to the Sichuan Basin, Ordos Basin, Tarim Basin Precambrian, Cambrian, Ordovician deep source rock); The criteria and evaluation techniques of effective source rocks under high evolution conditions; The issue of existing hydrocarbon under deep buried (over 6000 meters) and high evolution conditions.
    2. The issue of whether deep carbonate reservoirs exist or not; Mechanism of pores generation (reserve), and the controlling factor analysis (Reef-facies strata, palaeokarst stratum and dolomite strata).
    3. Mechanism of oil and gas (mainly natural gas) migration in deep basin, and the relationship between gas and source rock through tracing technology.
    4. Understanding of the basic geologic conditions of forming large - scale deep carbonate oil and gas fields.
Are there any articles or books that you would like to recommend?

  1. Zhou W., Xu H., Yu Q., Xie R.C., Deng K. 2016. Shale Gas Bearing Property Difference Between Wufeng -Longmaxi Formation and Niutitang-Qiongzhusi Formation of Sichuan Basin and Surrounding Areas and its Cause Analysis, Lithologic Reservoirs, 27(6): 8-12.
  2. Zhou, Q., Dilmore, R., Kleit, A., Wang, J. Y. 2016. Evaluating Fracture-Fluid Flowback in Marcellus Using Data-Mining Technologies. SPE-173364-PA. SPE Production & Operations. http://dx.doi.org/10.2118/173364-PA
  3. Xu H., Zhou W., Xie R.C., Da L.N., Xiao C., Shan Y.M., Zhang H.T. 2016. Characterization of Rock Mechanical Properties Using Lab Tests and Numerical Interpretation Model of Well Logs. Mathematical Problems in Engineering, Article ID 5967159, 13 pages.
  4. Cao Q., Zhou W., Deng H.C., Chen W.L. 2015. Classification and Controlling Factors of Organic Pores in Continental Shale Gas Reservoirs Based on Laboratory Experimental Results. Journal of Natural Gas Science and Engineering, 27, 1381-1388.
  5. Zhou W., Deng H.C., Zhao G.L. 2009. Quantitative Evaluation of Crack Distribution in the Upper Slip Failure Region of the Upper Cretaceous Shuibiba Formation in Daleel Oilfield, Oman. [J]. Journal of Minearal and Rock, 29 (4): 53-59.
  6. Zhou W., Yan C.H., Wang S.Z. 2007. Evaluation method and application of present ground stress field of oil and gas reservoir [M]. Chengdu: Geology Publishing House.
  7. Zhou W. 1998. Evaluation Method of Fractured Oil and Gas Reservoirs [M]. Chengdu: Sichuan Science and Technology Press.

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