Synthetic rock samples are widely used during oil exploration and production in rock physics, rock mechanics and petrophysics to simulate natural rock in the case of the lack of adequate natural rock samples or an alternative solution
mimicking natural rock characteristics. Hence, the synthetic rock samples can help to investigate hydrocarbon accumulation and migration, geophysical characteristics and the physical and chemical mechanisms in reservoir rocks. We review the experimental methodologies used to construct synthetic rock samples including cementation, sintering, cold/hot pressing, 3D printing and the cooling-pressing process. Based on these methodologies, synthetic samples are used to mimic sandstone, fractured porous rocks, shales, carbonates and gas hydrate. Synthetic rock samples can be used in experiments on seismic scattering, anisotropy, attenuation, seismo-electric effects, wave-induced fluid flow mechanism, shale brittleness and sweet point analysis, elastic/electric/mechanic properties of gas hydrate, etc. Synthetic rock samples present more and more similarity to natural rocks in pore structure, porosity, permeability, pore characteristics, mineral components, fluid saturation, micro-structure, etc. When focusing on unconventional reservoir rocks, such as tight sandstone, fractured rocks, shales, carbonates and gas hydrate, synthetic rocks with controlled parameters can provide samples with a single variable to investigate fluid flow, elastic properties, electromagnetism properties, mechanical properties. These can be used to quantitatively characterize the fluid flow transportation, elastic wave propagation, electromagnetism field, rock failure and other physical or chemical mechanisms, hence help to reduce the ambiguity and improve the accuracy in hydrocarbon exploration and production. Together with natural rocks, using synthetic rocks can reveal the effects of rock properties on rock physics characteristics. However, the application of synthetic rocks for rock mechanics laboratory study still has some limitations. The rock mechanics properties related to pore structure, mineral components, grain size, cementation, etc., synthetic rocks are not yet reliable enough to simulate natural rock mechanics characteristics. Meanwhile, the main targets for petroleum exploration and production are becoming unconventional reservoirs with more complex reservoir properties. Hence the feasibility and accuracy of simulating reservoir rocks with comprehensive complexities should be closely examined during laboratory study based on synthetic rocks. In general, synthetic rock still has some intrinsic drawbacks compared to natural rock (simple pore structure, different cementation, comparatively high porosity and permeability, etc.). Techniques for construction synthetic rock should be updated to improve the similarity between synthetic and natural rocks and to enhance the feasibility of using synthetic rock for laboratory study and industrial production.
Key words：
synthetic rock; rock physics; synthetic sandstone; fractured media; synthetic shale; gas hydrate; wave-induced fluid flow; anisotropy; brittleness
DING Pinbo, WEI Jianxin, DI Bangrang, LI Xiang-yang. Progresses of rock physics laboratory study based on synthetic rock samples. Petroleum Science Bulletin, 2021, 04: 576-594. doi: 10.3969/j.issn.2096-1693.2021.04.040
