热采条件下砂岩储层矿物转化的实验研究

研究了中国渤海湾北部油藏区砂岩储层中粘土矿物在高温、高压流动 条件下矿物组 分和体系结构的变化，原样包含石英、长石及粘土矿物等。提供了两组岩芯流动实验的结果 ，测试了样品在150℃、200℃、250℃，pH值为9、11、13下的反应结果，并对实验前后的样 品做了X射线衍射分析、电子探针分析。实验结果表明，粘土矿物的转化和迁移是造成储层 伤害的一个重要原因，一些离子对矿物反应有重要的影响作用。如何在开采过程中有效防止 易膨胀粘土及易迁移粘土的生成是保持储层渗透性的关键。实验结果可用于砂岩储层的注热 水/汽开采过程。

Experimental Study on Mineral Transformation in Sandstone Reservoir under EOR Conditions

The changes in clay mineral compositions and system fabrics in reservoir sandstone were studied under the high temperature－pressure and fluid circulation condition. The original samples contain quartz, feldspar and clay m inerals. Two core samples were taken for experiments at the temperatures of 150 ℃, 200℃, 250℃ and the pH values of 9, 11, 13. We find that the condition with a temperature of 250℃～300℃ and a pH of 9 is good for enhanced oil recovery ( EOR). The samples were also studied by means of X-ray diffraction and electron m icroprobe analysis. The results suggested that the transformation and migration of the clay minerals is the most important factor that causes damage of reservoir. Some tra nsitional products such as illite, zeolite, gibbsite and montmorillonite, were f ound. It's also detected that some ions in the injection water heavily infl uence EOR because they control the clay minerals reactions. How to prev ent the appearance of swellable and migratable clays is the key to protect perme ability of the reservoir. The results of this paper can be applied to the process of the steam injection or flood injection in reservoir sandstone.