Geomechanical Characterization of the Wufeng and Longmaxi Shales: Mechanical and Velocity Anisotropy, Static and Dynamic Moduli

被引：0
作者：
Dong K. [1 ]
Ding J. [2 ]
Hou B. [3 ]
Wang X. [1 ]
Kou R. [4 ]
机构：
[1] Department of Geology and Geophysics, Texas A&M University
[2] College of Petroleum Engineering, China University of Petroleum-Beijing
[3] Harold Vance Department of Petroleum Engineering, Texas A&M University
来源：
SPE Reservoir Evaluation and Engineering | 2023年 / 26卷 / 02期
关键词：
Anisotropy - Compressive strength - Ductile fracture - Dynamics - Hydraulic fracturing - Microcracks - Seismic design - Seismology - Shear waves;
D O I：
10.2118/212844-PA
中图分类号：
学科分类号：
摘要：
The Wufeng and Longmaxi shales of Sichuan Basin, Southwest China have been the primary targets for shale gas development. Because hydraulic fracturing and seismic interpretation require detailed characterization of formation mechanical properties, a sufficient understanding of anisotropy and elastic behavior in Wufeng and Longmaxi shales is necessary. In this study, we conducted Brazilian and triaxial tests and ultrasonic velocity measurements to characterize tensile and compressive strengths and P- and S-wave velocities, respectively. Shale samples were cored at a range of orientations relative to bedding and tested at multiple confining pressures, which allowed a detailed study of mechanical and velocity anisotropy, static and dynamic moduli. Our experimental work shows that Wufeng and Longmaxi shales possess similar compressive strength and associated anisotropy with other shale formations but apparently weaker tensile strength anisotropy and velocity anisotropy. These two shales also exhibit much lower static moduli than dynamic values, which are interpreted to be caused by compliant pores such as microcracks and fractures. Comparison between Wufeng and Longmaxi shales reveals distinct levels of heterogeneity. Wufeng shale shows more pronounced heterogeneity regarding measured tensile and compressive strengths as well as elastic moduli. These general characteristics of Wufeng and Longmaxi shales provide valuable first-order understanding regarding anisotropy, heterogeneity, and elastic behavior. Utilizing this understanding could help improve hydraulic fracture design and seismic data interpretation. Copyright © 2023 Society of Petroleum Engineers.
引用
收藏
页码：261 / 270
页数：9
相关论文
共 73 条
[1]  
Ambrose J., Zimmerman R. W., Suarez-Rivera R., Failure of Shales under Triaxial Compressive Stress, the 48th US Rock Mechanics/Geomechanics Symposium, (2014)
[2]  
Bauer A., Bhuiyan M. H., Fjaer E., Et al., Frequency-Dependent Wave Velocities in Sediments and Sedimentary Rocks: Laboratory Measurements and Evidences, Lead Edge, 35, 6, pp. 490-494, (2016)
[3]  
Bieniawski Z. T., Hawkes I., Suggested Methods for Determining Tensile Strength of Rock Materials, Int J Rock Mech Min Sci, 15, 3, pp. 99-103, (1978)
[4]  
Brotons V., Tomas R., Ivorra S., Et al., Improved Correlation between the Static and Dynamic Elastic Modulus of Different Types of Rocks, Mater Struct, 49, 8, pp. 3021-3037, (2016)
[5]  
Chen J., Lan H., Macciotta R., Et al., Anisotropy Rather than Transverse Isotropy in Longmaxi Shale and the Potential Role of Tectonic Stress, Eng Geol, 247, pp. 38-47, (2018)
[6]  
Chen S., Zhu Y., Qin Y., Et al., Reservoir Evaluation of the Lower Silurian Longmaxi Formation Shale Gas in the Southern Sichuan Basin of China, Mar Pet Geol, 57, pp. 619-630, (2014)
[7]  
Deng J., Wang C., Zhao Q., Et al., Depositional and Diagenetic Controls on Macroscopic Acoustic and Geomechanical Behaviors in Wufeng-Longmaxi Formation Shale, Front Earth Sci, 9, (2021)
[8]  
Dewhurst D. N., Siggins A. F., Impact of Fabric, Microcracks and Stress Field on Shale Anisotropy, Geophys J Int, 165, 1, pp. 135-148, (2006)
[9]  
Dong D., Shi Z., Guan Q., Et al., Progress, Challenges and Prospects of Shale Gas Exploration in the Wufeng–Longmaxi Reservoirs in the Sichuan Basin, Nat Gas Ind B, 5, 5, pp. 415-424, (2018)
[10]  
Technically Recoverable Shale Oil and Shale Gas Resources: An Assessment of 137 Shale Formations in 41 Countries Outside the United States, (2013)
12345678