徐家围子断陷深层天然气盖层特征及封盖性评价

Cap-Rock Characteristic and Sealing Ability Evaluation of Deep Xujiaweizi Fault Depression

利用钻井、测井和分析测试资料,结合天然气气藏剖面可知:徐家围子断陷共发育两种类型盖层,即泥岩和火山岩。通过对徐家围子断陷深层天然气盖层识别标志、分布、封闭能力及对天然气成藏与分布控制作用的分析表明:徐家围子断陷深层天然气发育泉一、二段,登二段两套区域性盖层;营一段顶部局部性盖层和营一段、三段内的隔层。区域性盖层和局部性盖层分布范围广、厚度大、排替压力较高、封闭能力强,控制着徐家围子断陷深层天然气的区域聚集与分布;隔夹层分布范围小、厚度薄、排替压力低、封闭能力弱,仅控制着天然气在储集层中的局部聚集与分布。

By use of drilling, logging and analysis data, combined with gas reservoir profile, it is concluded that there are two types of cap-rocks in Xujiaweizi fault depression, that is, mudstone and volcanic rock. By analyzing the identification mark, distribution and seal ability of cap-rock of deep gas in Xujiaweizi fault depression and its controlling action to gas accumulation and distribution, it is considered that there are two sets of regional cap-rocks （K1q^1＋2 and K1d^2）, local cap-rock （K1yc^1） on top, and interlayers in K1yc^1 and K1yc^3 of deep gas in Xujiaweizi fault depression. Regional and local caprocks are widely distributed with large thickness, higher displacement pressure and strong seal ability, which control regional accumulation and distribution of deep gas in Xujiaweizi fault depression; Interlayers are limited distributed with thin thickness, low displacement pressure and weak seal ability, which only control local accumulation and distribution of gas in reservoir.