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致密砂岩具有一定的各向异性。本文通过不同方向样品的声速测量及相关配套实验对致密砂岩进行了孔隙结构及各向异性分析,同时与页岩进行了对比。结果表明,致密砂岩样品所表现出的各向异性主要是由沉积环境差异形成的成分层、薄互层造成,具有典型的TI介质特征。不同方向杨氏模量随围压增加而增大,泊松比变化不明显。各向异性系数均随有效压力增加而减少,同时ε与γ和δ之间存在一定的线性关系。最后总结了不同地区的各向异性规律,为不同地区选择适合的评价模型奠定了基础。本次研究可为致密砂岩的测井评价、地震资料解释及压裂开发提供实验依据。
Tight sandstone has some anisotropy. In this paper, the pore structure and anisotropy of tight sandstone were analyzed by sound velocity measurement and related experiments in different directions, and compared with shale. The results show that the anisotropy exhibited by the tight sandstone samples is mainly caused by the difference of depositional environment and the formation of thin interlaminar layers, which has the typical characteristics of TI media. Young’s modulus in different directions increases with the increase of confining pressure, Poisson’s ratio does not change obviously. The anisotropy coefficient decreases with the increase of effective pressure, and there is a certain linear relationship between ε and γ and δ. Finally, the law of anisotropy in different regions is summarized, which lays a good foundation for choosing suitable evaluation models in different regions. This study can provide experimental evidence for logging evaluation of tight sandstone, interpretation of seismic data and development of fracturing.