摘要:
碎屑岩压裂缝是一种岩石受到纵向或侧向应力时,碎屑岩中颗粒接触点处承受较大的压强而产生的颗粒内部裂缝,这种裂缝的分布大部分限于碎屑颗粒的内部,从而有别于由构造应力产生的构造裂缝。对我国西部地区油气盆地中碎屑岩压裂缝的研究表明,这种压裂缝的发育程度与粒级、碎屑颗粒组分、填隙物含量有密切的关系。它多发育于粗砂岩和砾岩中,发育压裂缝的碎屑颗粒主要为刚性颗粒及凝灰岩岩屑和火山岩岩屑,在相同粒级和碎屑颗粒组份构成相当情况下,压裂缝发育程度与岩石中填隙物所占的百分数成反比关系,填隙物占岩石的百分数越少,压裂缝越发育。此外这种压裂缝在没有构造应力而仅有纵向岩柱压力的条件下也可以产生,从而为油气聚集提供了新的储集空间和渗流通道,拓宽了深部油气勘探的领域;同时对提高油气采收率也有重要的意义。
Abstract:
Crushed fracture in clastic rock is created under great press from the gravity of over layer or giant stress by sides, as the contact point of the grain bear big intensity of pressure than others. As the crushed fracture are distributed only within the grain, it can be distinguished from the fracture created by tectonic stress. By studying the crushed fracture in clastic rock of the oil & gas-bearing basin in the western China, it can be seen that the development degree of the crushed fracture has close relation to grain size, type of detrital minerals and the amount of interstitial material. The crushed fracture is easier developed in the coarse-sand rock and conglomerate, and the grains that developed crushed fracture are mostly rigid or come from tuff and lava. Under the same grain size and type of detrital minerals, the development degree of crushed fracture has close relation with the scale of interstitial material in rock. As the fracture can be created in the press of the gravity of overburden rock, and the fracture provide space for oil and gas, it will enlarge the field of petroleum exploration, at the same time, it have great significance in improving oil recovery.
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