川西南地区须三段底部岩性特征及识别  

LITHOLOGICAL CHARACTERISTICS AND ITS RECOGNITION OF T_3x_3 IN SOUTHWEST SICHUAN BASIN

作　　者：邢会民[1] 韩永刚[2] 余彬 李斌[2] 罗谋兵[2] 

机构地区：[1]西南石油大学 [2]四川石油管理局地质勘探开发研究院

出　　处：《天然气工业》2007年第11期46-48,共3页Natural Gas Industry

摘　　要：四川盆地西南部上三叠统须二段为区域上的主要产层，其顶部裂缝发育，钻井中易井漏、垮塌，一般设计在距须二段顶3～5m下油层套管固井。因此，卡准须三段底部已成为录井技术的关键环节。为此，从沉积环境、岩性、厚度分析了须三段的地层特征，表明具有岩性复杂、厚度变化大、砂体不稳定、无标志层等4个特点。首次将须三段划分为上、中、下3个亚段，并指出须三段底部的砂岩主要为深灰色岩屑粉砂岩、细砂岩，与中部和上部岩屑相比，石灰质、石英含量增加，白云石岩屑含量明显增加。这是判断须三段底部的主要标志。按照这些主要标志录井，已成为川西南部地区须二段下入油层套管的卡层依据。The Xu 2 section of Upper Triassic T3x2 in Southwest Sichuan Basin is a locally main producing payzone with very developed fractures at the top of the reservoir, which will derive in the leakage and collapse in the process of the drilling, generally, the casing will be designed and put into 3—5 m from the bottom of T3x3 to T3x2 for well cementation. Therefore, it is the key cycle of the logging technique to determine the bottom of T3x3 accurately. So, the paper analyzed the strata features of T3x3 in terms of sedimentary environment, lithology, and thickness, and put forward that T3x3 had four properties, such as complex lithology, strong thickness variation, unstable sandstone, as well as no horizon marker. The paper divided T3x3 into three sublayers, including the upper, middle and lower for the first time, and brought forward that the sandstone in the lower of T3x3 primarily consisted of dark-grey lithic siltstone and packsand. Compared with the upper and middle sublayers, its calcareous and quartz contents increased, and the doloclast contents distinctly increased, which was the main symbol differentiating the lower of T3x3. The logging on these main symbols has become the main evidences putting the casing into the oil layer of T3x2 in Southwest Sichuan Basin.

关 键 词：四川盆地 西南 晚三叠世 岩性识别 录井 

分 类 号：P618.13[天文地球—矿床学]