西峰油田长8储层的酸敏性评价

Acid sensitivity evaluation at Chang8 reservoir in Xifeng Oilfield

针对西峰低渗油藏在酸处理过程中存在井间差异的问题,从低渗砂岩储层的特殊地质特征出发,以西峰油田长8储层为例,首先选取不同矿物组成的岩样模拟酸化作业条件进行实验评价,并与已有常规酸化实验评价进行对比;其次对酸岩反应前后孔隙结构变化进行对比研究;最后对岩石酸敏性机理进行分析。结果表明,不同黏土矿物的溶蚀率不同,较低渗透率的岩心酸敏损害程度一般较高;酸化后铁沉淀较为严重,应对其进行相应的预防。因此一方面根据地质特征使用与之配伍的酸液配方,另一方面要具体考虑不同井层间的孔隙充填物成分,减小酸处理过程中的井间差异。

This paper is aimed at the problem that there are differences between wells during acid treatment at Xifeng low permeability reservoir. From analysing particular geologic characteristic of low permeability sandstone reservoir, taking Chang8 reservoir in Xifeng Oilfield as an example, firstly, selecting the rock sample with different mineral association, we simulate the acidating operation to evaluate the experiment and to compare with conventional test evaluation. Secondly, we comparatively study the changes in pore structure before and after acid reaction with the rock. And finally, the mechanism of acid sensitivity is analyzed. The results indicate that different clay mineral has different corrosive rate and cores with low permeability have high extent of damage after acid treatment. The problem of iron precipitation is serious after acidification, so measures must be taken to prevent the iron precipitation. Therefore, on the one hand, compatible acidizing fluid in accordance with geologic characteristic should be chosen and, on the other hand, composition of pore filling between layers in different wells should be specifically considered in order to reduce the difference between layers.