地层碱化的试验研究

LABORATORY STUDY ON FORMATION ALKALINE TREATMENT

提出了地层碱化的新措施,研究了与本措施有关的岩石的碱溶和沉积、原油的乳化和破乳两个问题.用溶液元素分析法研究了静态条件下岩石碱溶规律,得出矿物碱溶顺序为;蒙脱石>高岭石> 伊利石> 正长石> 石英> 绿泥石,这表明碱化适宜地层为高粘土含量的高温低渗砂岩地层.用浊度法研究了 pH值和电解质对碱溶产物沉积的影响.结果表明,当 pH值降至 9～10或遇Ca2+、Mg2+时,碱溶产物析出凝胶或无机沉淀.用不稳定系数法研究了不同因素对原油乳化和破乳的影响,得出注碱乳化配方.该配方由适当碱浓度和最佳盐含量组成,pH值降低或遇ca2+、Mg2+,可促进注碱乳化原油破乳.此外,通过多点测压渗流装置模拟了油水井碱化过程,证实碱化具有近井增注、远井调剖效果.

This paper deals with rock dissolution and deposition in aqueous alkaline solutions and emulsification and demulsification performance of crude oil. Rock dissolution was researched by analysing the elements (Si, Al and OH ) in supernatants under static condition. The result shows that the degree of mineral dissolution was in following order: Montmorillonite>Kaolinite>Illite>Ortho-clase>Quartz>Chlorite. The alkaline treatment is suitable for sandstone formation of high clay content, high temperature and low permeability. By using turbidity as an index, the effect of pH value and electrolyte on deposition of rock dissolution product was studied. The product could turn out to be inorganic precipitation or gel shutoff agent when it coincided with Ca2+ ,Mg2+or pH value was declined to 9~10. With the method of Unstability Index, the effects of the concentration of alkali and salt, temperature and electrolyte on emulsification and demulsification performances of crude oil were discussed. The effects of injection-increasing near wellbore and profile-improving far from wellbore of alkaline treatment were confirmed by flow experiments.