鄂尔多斯盆地陇东地区复杂岩性铝土岩储层改造酸化液研究及应用

Research and application of acidizing fluid for complex lithology bauxite reservoir stimulation in the Longdong area of the Ordos Basin

鄂尔多斯盆地陇东地区铝土岩储层纵向岩性复杂,矿场改造过程中储层压不开及难压的问题突出。为解决陇东铝土岩施工压力高和储层难破裂的难题,提出在酸溶水铝石之外以黏土矿物为主要目标的酸液研发思路,创新形成了多效耦合活性酸体系。缓速机理及电离实验表明,多效酸是一种多元弱酸,在溶液中可形成多级可逆平衡体系并存在6种型体,主要通过多级电离特性来达到对岩石矿物的缓速效果;溶蚀实验表明,多效酸体系对Ⅱ、Ⅲ类铝土岩岩心溶蚀率达20%~42%;螯合测试实验表明,多效酸能有效抑制氟化钙沉淀的产生;通过对主剂活性酸及助剂缓蚀剂的优化与评价,优选了一套多效酸体系。在矿场完成的先导性试验表明,降压可达10~22 MPa,初步显示出较好的降压改造效果。

The vertical lithology of bauxite reservoirs in the Longdong area is complex,and the problems of fracturing failure and difficulty during the fracturing process are prominent.In order to solve the problems of high construction pressure and difficulty in fracturing reservoirs in Longdong bauxite,an acid research and development approach with clay minerals other than acid soluble bauxite as the main target has been proposed,and a multi effect coupling active acid system has been innovatively formed.The retarding mechanics and ionization experiments indicate that multi-functional acids are a type of weak acid that can form a multi-level reversible equilibrium system in solution and have six types.They mainly achieve a slowing effect on rocks and minerals through multi-level ionization characteristics.The dissolution experiment shows that the dissolution rate of the multi effect acid system on class II and III bauxite rock cores reaches 20%-42%.The chelation test experiment shows that the multi effect acid can effectively inhibit the production of calcium fluoride precipitation.By optimizing and evaluating the main active acid and auxiliary corrosion inhibitors,a multi-functional acid system was optimized.The mine has completed pilot tests,with a pressure drop of up to 10-22 MPa,indicating a good effect of pressure reduction transformation.