泥岩超压释放深度和次数及其主要影响因素

Release depth and times of overpressure of mudstone and its influential factors

在泥岩超压形成机制和条件研究的基础上,通过泥岩超压形成与演化规律的研究,建立了一套泥岩超压释放深度和次数的研究方法,利用此方法通过理论计算对泥岩超压释放深度和次数的主要影响因素进行了研究,得到泥岩超压是其压实过程中的阶段产物,只有当压实成岩达到一定程度后方可形成,当超过泥岩破裂极限后便发生破裂超压释放,超压降低以致消失。泥岩超压释放主要受压实速率和欠压实程度的影响,随着压实速率和欠压实程度增大,泥岩超压释放深度逐渐减小,压实速率对泥岩释放深度的影响较欠压实程度对泥岩超压释放深度的影响大,尤其是当压实速率小于0.0005时,这种影响程度更大。泥岩超压释放次数也主要受压实速率和欠压实程度的影响,随压实速率和欠压实程度增大,泥岩超压释放次数增多,在压实速率小于或等于0.001和欠压实程度(声波时差)小于500μm/s时,泥岩超压释放次数增大幅度相对较小,在压实速率大于或等于0.001和欠压实程度(声波时差)大于500μm/s时,泥岩超压释放次数增大幅度相对较大。

Based on the research of formation mechanism and conditions of overpressure of mudstone, a research method on the relation between depth and times of overpressure of mudstone was established under the formation and evolution law of overpressure of mudstone. This method was utilized to study the factors that influence the release depth and times of overpressure of mudstone by theoretical calculating; we found overpressure of mudstone is the periodical product in the compacting process which can only form when the compaction diagenesis comes to certain extent. When it exceeds the mudstone collapse limit, it will release by collapse, which will reduce or vanish. The overpressure of mudstone release depth are mainly influenced by the compaction velocity and uncompaction degree, the overpressure of mudstone depth reduce with the increase of compaction velocity and uncompaction degree, the effect that compaction velocity on the mudstone release depth is greater compared with that of uncompaction has on the mudstone overpressure release depth, especially when the velocity is less than 0. 000 5. The times of overpressure of mudstone are also mainly influenced by the compaction velocity and uncompaction degree, the times will become more with the increase of compaction velocity and uncompaction degree. When the compaction velocity is less or equal to 0. 001 and uncompaction degree （SDT） is less or equal to 500μm/s, the overpressure of mudstone times increase greater, while on the contrary it increase lesser.