Fused breccia tuff occurs globally, but its formation mechanism is very controversial. Volcanic reservoirs have developed at the bottom of the Permian Fengcheng Formation in the Wuxia region of the Junggar Basin, and here, the lithology is fused breccia tuff. The reservoir porosity is mainly vesicles, but the development and relative filling of the vesicles vary spatially, resulting in strong reservoir heterogeneity. Through core and thin section observations and structural analysis, and combined with reconstructions of the paleosedimentary environment, we discussed in detail the formation mechanism of the fused breccia tuff reservoir. Our conclusions are as follows. In the high-temperature and high-pressure environment of the deep crust, intermediate acidic lava containing volatile components rapidly rose to the earth’s surface along a fault. The volatile components in the lava foamed strongly and then exploded due to the sharp decline of pressure and temperature. A small part of the volcanic dust and pyroclastic material was erupted into the upper atmosphere. Most of the magma became magmatic pyroclast, vitric pyroclast, rock debris, dust, and other matter. This material was in a semimolten state and overflowed into a nearby low-lying lake. The extremely high-temperature pyroclastic flow quickly vaporized the water into high-pressure water vapor, which was squeezed into the pyroclastic flow and became mixed with other volatiles in the foam. On cooling, the pyroclastic material solidified into rock, and the vesicles were preserved. In a later period, due to strong tectonic movement, faults and fractures developed, surface water penetrated into the vesicles along the faults and fractures, and silica and other substances were deposited, filling the primary vesicles. To quantify the development and relative filling of vesicles, drilling parameters were used to establish different geologic models, and wave equation forward modeling was used to obtain a relationship between the development and filling of vesicles, and the seismic amplitude. The 3D seismic amplitude attributes were then extracted to predict the extent of the reservoir, yielding prediction results consistent with the drilling observations.

中文翻译：

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准噶尔盆地乌夏地区二叠系熔融角砾凝灰岩储层形成机制及预测方法

熔融角砾凝灰岩在全球范围内均有分布，但其形成机制争议很大。准噶尔盆地乌夏地区二叠系风城组底部发育火山岩储层，岩性为熔合角砾凝灰岩。储层孔隙度以囊泡为主，但囊泡的发育和相对充填在空间上存在差异，储层非均质性较强。通过岩心和薄片观察和构造分析，结合古沉积环境重建，详细讨论了熔合角砾凝灰岩储层的形成机制。我们的结论如下。在地壳深部的高温高压环境中，含有挥发性成分的中酸性熔岩沿着断层迅速上升到地表。熔岩中的挥发性成分剧烈发泡，然后由于压力和温度的急剧下降而爆炸。一小部分火山尘和火山碎屑物质喷发到高层大气中。大部分岩浆变成岩浆火山碎屑、玻璃质火山碎屑、岩屑、灰尘和其他物质。这种物质处于半熔融状态，溢出到附近的低洼湖泊中。极端高温的火山碎屑流迅速将水汽化成高压水蒸气，高压水蒸气被挤压到火山碎屑流中，并与泡沫中的其他挥发物混合。冷却后，火山碎屑材料凝固成岩石，囊泡得以保存。后期由于强烈的构造运动，断层和裂缝发育，地表水沿断层和裂缝渗入囊泡中，沉积二氧化硅等物质，填充初级囊泡。为了量化囊泡的发育和相对充填，利用钻井参数建立不同的地质模型，并利用波动方程正演建模得到囊泡发育和充填与地震振幅之间的关系。然后提取 3D 地震振幅属性来预测储层的范围，产生与钻井观测一致的预测结果。利用波动方程正演模拟得到囊泡发育充盈与地震振幅的关系。然后提取 3D 地震振幅属性来预测储层的范围，产生与钻井观测一致的预测结果。利用波动方程正演模拟得到囊泡发育充盈与地震振幅的关系。然后提取 3D 地震振幅属性来预测储层的范围，产生与钻井观测一致的预测结果。