研究了埋藏-成岩-抬升变形过程中盖层封闭性的演化特点,开展了构造变形过程中盖层破裂实验。认为泥岩在高演化阶段封闭性变差并不具有普遍性,在深埋条件下和构造稳定区,高演化泥岩仍可具有良好的封闭性;构造抬升是盖层封闭性发生破坏的主要因素;力学实验表明,膏盐岩盖层在极小的埋深(1000m左右)下就有很强的塑性,其极限强度很低,应变很大,是优质盖层;泥岩盖层在浅埋藏条件下,容易产生破裂,但在深埋条件下(围压超过50MPa),泥岩表现出塑性流变,仍然具有较好的封闭条件;泥灰岩破裂强度随着埋深的变化不明显,始终表现为比较强的脆性,高压下容易产生破裂。
It has been studied about sealing capacity evolution of cap rock in the process of buried, diagenesis and uplift. The broken test of cap rock modeling tectonic deformation has been done. According to the test, we consider that it is not a common rule which the sealing capacity of mud stone becoming poor at high evolutionary stage, it has good sealing capacity under deep buried conditions in tectonic stable area. Uplift is the main factors that destroy the sealing capacity of cap rocks. Stress test shows that gypsum rock has strong ductile under little buried depth(about 1 000 meters). The gypsum rock is good cap rock with low ultimate strength. Under shallow buried condition, mudstone is subject to crack. However, it shows ductile and good sealing capacity under deep buried condition (confine pressure beyond 50 MPa). The rupture strength of muddy limestone has indistinct change with buried depth. It always shows brittle, and be subject to crack under high pressure.