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通过流体在岩石内部孔隙中运移与反应的实验方式,开展0.2%乙酸与4种类型碳酸盐岩的溶蚀实验,对溶蚀作用的控制因素及溶蚀效应进行研究。结果显示碳酸盐岩溶蚀量与温度呈反比、与压力成正比,且温度效应大于压力效应,因此浅埋藏低温环境是碳酸盐岩规模溶孔形成的有利条件。定量对比溶蚀前后孔隙体积和渗透率的变化,以及岩石内部孔隙演化,指出孔隙结构明显控制碳酸盐岩溶蚀效应和溶孔演化。孔隙型白云岩的孔隙分布具均质性,经历溶蚀后,孔隙体积和渗透率相应增加,且增加的是基质孔隙,储集空间类型保持为孔隙型;孔隙型灰岩由于初始孔隙和组构非均质性强,溶蚀导致孔隙体积和渗透率增加均较显著,但增加的是裂缝型孔隙,储集空间类型演化为缝洞型;溶蚀对裂缝-孔隙型白云岩和裂缝型灰岩的渗透率改善显著,渗透率增加2~3个数量级,且主要增加沿溶缝发育的孔(洞),储集空间类型演化为缝洞型。
The experiment of 0.2% acetic acid and 4 types of carbonate rocks was conducted to study the controlling factors of dissolution and the dissolution effect through the experiment of fluid migration and reaction in the pores of rock. The results show that the carbonate dissolution rate is inversely proportional to the temperature and proportional to the pressure, and the temperature effect is greater than the pressure effect. Therefore, shallow burial and low temperature environment are favorable conditions for the formation of carbonate pores. Quantitative comparison of changes in pore volume and permeability before and after erosion, as well as the evolution of porosity inside the rock, indicates that the pore structure significantly controls carbonate dissolution and pore evolvement. Pore-type dolomite has homogeneous pore distribution. After erosion, the pore volume and permeability increase correspondingly, and the matrix porosity increases and the type of reservoir space remains as pore type. Due to the initial porosity and structure The heterogeneity is strong and dissolution leads to the increase of pore volume and permeability. However, the increase of fractured pores and the evolution of the reservoir space type to the fracture-cave type; the dissolution to the fractured-pore dolomite and the fractured limestone Permeability improved significantly, the permeability increased by 2 to 3 orders of magnitude, and mainly increased along the pore hole (cave) developed, the type of reservoir space evolved into a fracture-hole type.