花土沟油田下油砂山组-上干柴沟组藻灰岩储层特征

Characteristics of algal limestone reservoirs in Xiayoushashan-Shangganchaigou Formations in Huatugou oilfield, western Qaidam basin

花土沟油田下油砂山组 -上干柴沟组藻灰岩储层主要有藻纹层灰岩、藻泥晶灰岩、亮晶鲕粒灰岩、亮晶介屑灰岩、亮晶藻团粒灰岩和陆屑泥晶灰岩等 ,其中前两类的储层物性较好。藻灰岩储层的形成主要受沉积环境的稳定性、早期淋溶和晚期胶结 -充填作用的控制。藻灰岩储层在测井曲线上显示出较高的自然伽马值 ,在地震剖面上表现为强反射特征。利用这些特征可以进行藻灰岩储层的横向展布分析。经几口井的试油 ,藻灰岩储层都有油气显示 。

Algal limestone reservoirs in Xiayoushashan Shangganchaigou Formations in Huatugou oilfield in western Qaidam basin mainly consist of algal laminated limestone,algal micrite,oosparite,sparry coquina,sparry algal lump limestone and terrigenous clastic micrite,of which the former two types of limestone have relatively good reservoir properties.The formation of algal limestone reservoirs has mainly been controlled by the stability of sedimentary environment,early eluviation and late cementation filling.Algal limestone reservoirs appear to have relatively high gamma ray value in well logs and strong reflectance signatures in seismic profiles.These characteristics can be used to determine lateral distribution of algal reservoirs.Formation testings in several wells have got oil/gas shows in algal limestone reservoirs,verifing that this type of reservoirs has good prospectiveness.