Abstract
The reservoirs in the western South China Sea oilfield are characterized by low permeability, poor pore connectivity, high laminated content, severe pollution, and prominent interlayer contradictions. For this reason, the water injection dilation technology exploits it. This paper examines the impact of water-injection technical parameters on the dilation of low-permeability reservoirs in the western South China Sea. In this paper, tests on uniaxial compressive strength, Kaiser acoustic emission effect, and true triaxial rock mechanics waterflood dilation physical simulation are conducted. Through uniaxial compressive tests, it is found that the uniaxial compressive strength of the rock in the target reservoir is 35.36 MPa, the elastic modulus is 10.39GPa, and the Poisson ratio is 0.15. The Kaiser acoustic emission test indicates that the vertical stress gradient of the target reservoir is 2.22 MPa/100 m, the maximum horizontal principal stress gradient is 2.04 MPa/100 m, and the minimum horizontal principal stress gradient is 1.67 MPa/100 m. Through a true triaxial rock mechanics simulation of water injection dilatation, it is found that the effect of water injection dilatation can be improved by pre-treating samples with stepped pore pressure, low injection rates, a cyclic oscillatory injection mode, and increased liquid viscosity. Using CT (Computed Tomography) scanning results and CT reconstruction of the sample, the maximum volume porosity can be increased to 7.13%. The test’s results can guide field construction of water-injection dilation.
Data availability
All data generated or analysed during this study are included in this published article [and its supplementary information files]. We have uploaded the raw data, except for those that can be represented in the paper, to the supplementary information files.
References
Jianzhong, L. I. U. et al. Progress and prospects of oil production engineering technologies in offshore oilfields of CNOOC[J]. China Offshore Oil Gas. 36 (5), 128–136 (2024).
SUN Fujie. Status and prospects of efficient development and EOR technologies in China offshore oilfields[J]. China Offshore Oil Gas. 35 (5), 91–99 (2023).
Chen, H. et al. Application and research into dilatation and injection enhancement technology for unconsolidated sandstone injectors in an offshore oilfield. Pet. Sci. Bull. 8(05), 649–659 (2023).
Samieh, A. M. & Wong, R. C. K. Modeling the responses of Athabasca oil sand in triaxial compression tests at low pressure. Can. Geotech. J. 35(2), 395–406 (1998).
Wong, R. C. K. Strain-induced anisotropy in fabric and hydraulic parameters of oil sand in triaxial compression. Can. Geotech. J. 40(1), 489–500 (2003).
Yuan, Y., Yang, B. & Xu, B. Fracturing in the oil sand reservoirs. In S.P.E.- 149308- MS. Paper presented at Canadian Unconventional Resources Conference. 15–17 November, Calgary, Alberta, Canada (2011).
Wong, R. C. K., Barr, W. E. & Kry, P. R. Stress-strain response of Cold Lake oil sand. Can. Geotech. J. 30(2), 220–235 (1993).
Yuan, Y., Xu, B. & Yang, B. Geomechanics for the thermal stimulation of heavy oil reservoirs. In SPE 150293 (2011).
ASTM International. Method for consolidated drained triaxial compression test for soils: ASTM D7181-11 (ASTM International, 2011).
Xin, Y. et al. Research on optimisation and application of rock dilation technology in offshore oilfields. Technol Superv. Pet. Ind. 41(10), 66–70. https://doi.org/10.20029/j.issn.1004-1346.2025.10.013 (2025).
Xu, B. & Wong, R. C. K. Coupled finite-element simulation of injection well testing in unconsolidated oil sands reservoir. Int. J. Numer. Anal. Methods Geomech. 37(18), 3131–3149 (2013).
Xu, B., Yuan, Y. & Wong, R. C. K. Modeling of the hydraulic fractures in unconsolidated oilsands reservoirs. BitCan Geosciences & Engineering Inc, ARMA-10-123 (2010).
Duncan, J. M. & Chang, C. Y. Nonlinear analysis of stress and strain in soils. J. Soil Mech. Found. Div. 96, 1629–1653 (1970).
Ulusay, R. The ISRM Suggested Methods for Rock Characterization, Testing and Monitoring: 2007–2014 (Springer, 2014).
Xu B. Consideration of geomechanics for in-situ bitumen recovery in Xinjiang, China. In SPE 165414 (2013).
Rowe, P. W. The stress-dilatancy relation for static equilibrium of an assembly of particles in contact. Proc. R. Soc. Lond. A Math. Phys. Sci. https://doi.org/10.1098/rspa.1962.0193 (1962).
Bolton, M. D. The strength and dilatancy of sands. Géotechnique 36(1), 65–78 (1986).
Lin, B. T. et al. Experimental study on dilation mechanism of micro-fracturing in continental ultra-heavy oil sand, Fengcheng Oilfield. Oil Drill. Prod. Technol. 38, 359–364 (2016).
Lin, B. T. et al. Prediction on the reservoir dilatation results by squeeze preprocessing in SAGD wells. Oil Drill. Prod. Technol. 40(3), 341–347 (2018).
Lin, B. T. & Jin, Y. Evaluation of the influencing factors of dilatancy effects by squeezing liquids in SAGD wells in the Fengcheng Oilfield of Xinjiang Oilfield. Pet. Drill. Tech. 46(6), 71–76 (2018).
Wang, Q. Q. et al. Effects of SAGD well squeeze dilatation on the circulating preheating and production. Oil Drill. Prod. Technol. 41(3), 387–392 (2019).
Ren, Y. et al. Mechanism of capacity dilation and enhanced water injection of deep tight sandstone- by taking X oilfield in the eastern South China as an example. Pet. Geol. Eng. 36(6), 82–87 (2022).
Li, X. L. et al. Roadway portal and self-moving hydraulic support for rockburst prevention in coal mine and its application. Phys. Fluids 36(12), 124136. https://doi.org/10.1063/5.0243798 (2024).
Jianhaia, M. & Sun, J. Calculation of formation stress using logging data. WLT 26(4), 347–351 (2002).
Hai-chao, S. H., Yuan-fang, C. H., Jing-yin, W. A. & Yi-zhong, Z. H. Principal direction differential strain method for in-situ stress measurement and application. Xinjiang Pet. Geol. 29(2), 250 (2008).
Wang, X. & Han, S. Application of acoustic emission technique in surrocking rock tectonic stress test. Coal Chem. Ind. 39(10), 93–96 (2016).
Wang, X. et al. Mechanical manifestation characteristics and damage evolution law of unloading perturbation damage in surrounding rock of deep roadways. Geomech. Geophys. Geo Energy Geo Resour. 11, 35. https://doi.org/10.1007/s40948-025-00956-0 (2025).
Chen, H. et al. Dilation potential analysis of low-permeability sandstone reservoir under water injection in the West Oilfield of the South China Sea. Processes 12(9), 2015 (2024).
Wu, S. et al. Experimental and numerical investigations on low-permeability sandstone under water injection-induced dilation in the west oilfield of the South China Sea. Processes 12(11), 2393 (2024).
Li, Z. Similitude and Modeling (Theory and Applications) (National Defence Industry Press, 1982).
Liu, S. M. et al. Experimental study of effect of liquid nitrogen cold soaking on coal pore structure and fractal characteristics. Energy 275(7), 127470. https://doi.org/10.1016/j.energy.2023.127470 (2023).
Qin, X. H. et al. Experimental study of relation between in-situ crustal stress and rock elastic modulus. Rock Soil Mech. 33(6), 1689–1695 (2012).
Acknowledgements
This work would not be possible without financial support from the National Natural Science Foundation of China (No. 52574008, 52204048); the Key Research and Development Program of Shaanxi (grant number 2025CY-YBXM-164) and the Joint Research Project of Research institutes of CNOOC (China) Co., Ltd. “Research on Physical Dilation and Injection Technology of Injection Well in Offshore Oilfield” (No.: YSLH-SZ 01 2023). Thank CNOOC Research Institute Co., Ltd. for providing technical support for marine low-permeability sandstone rock dilation. Thank the Department of Geology at Northwest University for providing us with an indoor test site, experimental technology, and support for numerical simulation technology.
Author information
Authors and Affiliations
Contributions
Conceptualization, Huan Chen, Yanfang Gao; Methodology, Dengke Li, Huan Chen, Yanfang Gao; Validation, Huan Chen, Xuelin Liang, Yanfang Gao; Formal analysis, Dengke Li, Zhi Huang; Investigation, Yanfang Gao; Resources, Huan Chen; Data curation, Dengke Li, Xuelin Liang; Writing—original draft, Dengke Li; Writing—review & editing, Dengke Li; Visualization, Zhi Huang; Supervision, Huan Chen, Yanfang Gao; Project administration, Yanfang Gao; Funding acquisition, Huan Chen, Yanfang Gao. All authors have read and agreed to the published version of the manuscript.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
Li, D., Chen, H., Liang, X. et al. Physical simulation test of true triaxial rock mechanics for waterflood dilation in offshore oilfields. Sci Rep (2026). https://doi.org/10.1038/s41598-026-42750-2
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-42750-2
