声波时差在研究非均质盖层综合封闭能力中的应用

The application of acoustic time in studying the sealing capability of inhomogeneous caprock

大庆石油学院,黑龙江大庆 163318

Daqing Petroleum Institute, Daqing 163318. China

为了利用声波时差资料研究非均质盖层毛细管综合封闭能力,在盖层毛细管封闭机理及影响因素分析的基础上,首先利用实测泥岩排替压力与声波时差之间的关系建立了求取实际地层中泥岩排替压力的公式;然后再利用砂岩和泥岩排替压力之间的关系,推导了求取砂岩排替压力的公式。通过砂、泥岩排替压力和砂、泥岩在非均质盖层中所占厚度的比值,利用串连原理建立了非均质盖层毛细管综合封闭能力的研究方法。将此方法应用于松辽盆地北部徐家围子地区登二段非均质盖层毛细管综合封闭能力的研究.结果表明.该地区泥岩盖层具有良好的毛细管综合封闭能力.对天然气的聚集保存十分有利。

In order to study the capillary sealing capability of in-homogeneous caprock by acoustic time, based on the analysis of capillary seal mechanism of caprock and its influence factors, a method for a large amount of displacement pressures of mudstone through the relation between and measured displacement pressure was presented. With the displacement pressure of sandstone and mudstone and the rati-o between thickness of sandstone or thickness of mudstone and thickness of inhomogeneous caprock, according to serial connection principle. The method was applied to study the comprehensive capillary seal ability of inhomogeneous caprock of k₁d₂ in Xujiaweizi region in the north of Songliao Basin. The research result shows that the mudstone caprock of K₁d₂ has the best comprehensive capillary sealing capability in Xujiaweizi region and it is the most favorable to gas accumulation and preservation.