陆西地区清水河组一段储层特征及差异性分析

为了厘清陆梁隆起西部清水河组一段砂（砂砾）岩储层特征及控制因素，指导甜点储层的勘探，通过大量岩石薄片、铸体薄片、扫描电镜、X衍射分析，并结合岩芯观察、物性及压汞分析，对清水河组一段砂岩和砂砾岩储层进行了对比研究。研究认为，两种储层宏、微观特征差异明显。（1）砂岩储层主要为中细粒长石岩屑砂岩，主要分布于研究区的北西侧；砂砾岩储层主要为细砾岩和砂质细砾岩，主要分布于研究区的北东侧。（2）砂岩储集空间以原生孔隙为主，斜长石溶蚀孔隙为辅；砂砾岩储集空间主要是粒间方解石溶孔。（3）砂岩储层平均孔隙度14%，砂砾岩为11%，砂岩储层物性好于砂砾岩储层，但孔喉结构砂砾岩储层较好，以大孔偏粗歪度为主。（4）砂岩受压实作用影响较强，北部构造高部位的河道砂岩（如夏盐8井区）因埋深较浅，压实较弱、物性较好；砂砾岩储层早期受强烈的碳酸盐胶结作用而致密化，储层物性受控于断层发育处的溶蚀作用。

Analysis on the Characteristics and Variations of Member 1 of the Qingshuihe Formation in the Luxi Region

To elucidate the reservoir characteristics and controlling factors of Member 1 of the Qingshuihe Formation (Qingshuihe Member 1), which lies to the west of the Luliang uplift, and to guide the prospecting of "sweet spots" in the reservoir, a comparative analysis between the sandstone and glutenite reservoirs of Qingshuihe Member 1 was performed through the analysis of a large numbers of rock thin-sections and casting thin-sections via scanning electron microscopy and X-ray diffraction, combined with the analysis of rock core observations, petrophysical properties, and mercury porosimetry. Significant differences were found between the microscopic and macroscopic characteristics of these reservoirs. (1) Sandstone reservoirs are mainly comprised of medium-to-fine grained feldspar lithic sandstones that are primarily distributed within the northwestern side of the research area, whereas glutenite reservoirs are mainly composed of fine conglomerate and sandy fine conglomerate that are mainly distributed in the northeastern side of the research area. (2) Reservoir spaces in sandstone are mainly comprised of primary pores, with plagioclase dissolution pores supplementing these spaces, whereas the main reservoir space in glutenite is comprised of intergranular calcite dissolution pores. (3) The average porosity of sandstone and glutenite reservoirs are 14% and 11%, respectively, indicating that sandstone reservoirs have better petrophysical properties than glutenite reservoirs. However, glutenite reservoirs have better pore-throat structures, as most of their pores are large and have coarse skewness. (4) Sandstones are strongly affected by compaction. The tectonically elevated Hedao sandstones in the north (e.g. the Xiayan-8 well) experienced weaker levels of compaction due to their shallow burial depths, and thus have better petrophysical properties. Intense carbonate cementation during the early stages of glutenite reservoir development led to the compaction of these reservoirs, and the petrophysical qualities of these reservoirs are determined by the effects of dissolution around locations where such faults developed.