Abstract:
Objective During the development of high temperature and high pressure carbonate oil and gas reservoir, white precipitate will be produced when high-density potassium formate completion fluid is mixed with acid solution.The study is aiming to optimize the performance of completion solution and achieve good compatibility with acid fluid.
Methods Through analyzing the precipitation rule of potassium formate completion fluid and acid fluid, the composition of solid precipitate, the dissociation degree of potassium formate in acid solution and the solubility of potassium chloride in acid fluid, the precipitation mechanism of potassium formate completion fluid in acid solution is revealed.
Results The results show that the acid environment affects the increase of dissociation degree of potassium formate and the decrease of solubility of potassium chloride. Potassium ions and chloride ions in the solution are adsorbed and eventually precipitated with potassium chloride crystals.
Conclusions Based on the above precipitation mechanism, the formula of potassium formate completion fluid compatible with acid solution is optimized. Its density is adjustable from 1.10 g/cm3 to 1.50 g/cm3 and its high temperature stability is good when it is compatible with acid solution.