Abstract Fewer studies have focused on subsurface deformation bands than on deformation bands in outcrops. In this work, we studied the subsurface deformation bands in high-porosity sandstones from the Shulu borehole in the Bohai Bay Basin. The Shulu borehole was drilled through the Xicaogu normal fault with a displacement of 140 m, and the recovered core contains deformation bands and fractures in the damage zones. This study focused on the structural characteristics of subsurface deformation bands with burial depths between 2504.4 m and 2506.2 m. The critical porosity limit of host sandstone for the formation of deformation bands and fractures was determined. The host sandstones in the Shulu borehole are predominantly arkose. The subsurface deformation bands in the Shulu borehole are suggested to be compactional shear bands. We find that the subsurface deformation bands have the identical characteristics to those in outcrops, except that they do not show a strong positive relief. These bands are characterized by protocataclasis and cataclasis and organized into localized and conjugate networks. Compared to the host rocks, the subsurface deformation bands show porosity reductions of 7.7-27.7% and permeability reductions of 1-3 orders of magnitude. Three porosity intervals of the host-rock with different deformation styles can be identified in the Shulu borehole core: 1) host sandstone with porosities greater than 14.3%, which completely develop deformation bands; 2) host sandstone with porosities less than 10.8%, which develop fractures; and 3) the transition zone, where the porosities of host sandstones are 10.8-14.3%, and the deformation styles are characterized by both deformation bands and fractures. The critical porosity limit of host rocks in terms of the formation of deformation bands and fractures suggests that the porosity is a major factor controlling the formation of fractures and deformation bands. Deformation bands and fractures have a counteraction effect on the fluid flow in the transition zone.

中文翻译：

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长石质砂岩孔隙度对变形带形成的临界控制——以渤海湾盆地束鲁穿越断层钻孔为例

摘要 与露头变形带相比，对地下变形带的研究较少。在这项工作中，我们研究了渤海湾盆地束鹿钻孔高孔隙度砂岩的地下变形带。束鹿钻孔穿过西草谷正断层，位移140 m，回收的岩心在损伤带包含变形带和裂缝。本研究重点研究了埋藏深度在 2504.4 m 至 2506.2 m 之间的地下变形带的结构特征。确定了形成变形带和裂缝的主砂岩的临界孔隙度极限。束鹿钻孔中的主砂岩主要是长石砂岩。建议疏鲁钻孔地下变形带为压实剪切带。我们发现地下变形带与露头中的变形带具有相同的特征，只是它们没有表现出强烈的正起伏。这些带的特点是原始催化裂化和催化裂化，并组织成局部和共轭网络。与围岩相比，地下变形带的孔隙度降低了 7.7-27.7%，渗透率降低了 1-3 个数量级。束鹿钻孔岩心可识别出三种不同变形方式的主岩孔隙度段：1）孔隙度大于14.3%的主砂岩，完全发育变形带；2) 孔隙度小于 10.8% 的主砂岩，发育裂缝；3) 过渡带，主砂岩孔隙度为 10.8-14.3%，变形方式具有变形带和断裂两种特征。围岩变形带和裂缝形成的临界孔隙度极限表明，孔隙度是控制裂缝和变形带形成的主要因素。变形带和裂缝对过渡带中的流体流动有反作用。