高密度甲酸钾完井液在酸液中的析出机理及配方优化

Precipitation mechanism and formulation optimization of high-density potassium formate completion fluid in acid solution

关键词:  甲酸钾完井液  酸液配伍性  析出机理  高密度  无固相完井液 

Key words:  potassium formate completion fluid  acid compatibility  precipitation mechanism  high density  solid free completion fluid

摘要:

目的 在高温高压碳酸盐岩油气藏开发过程中,高密度甲酸钾完井液与酸液混合会产生白色沉淀物。优化完井液性能,以实现高密度甲酸钾完井液与酸液良好的配伍性。方法 通过分析甲酸钾完井液与酸液析出沉淀规律、固相沉淀物组成、甲酸钾在酸液中解离度和KCl在酸液中的溶解度,揭示了甲酸钾完井液在酸液中的析出机理。结果 酸液的酸性环境增大了甲酸钾的解离度、降低了KCl的溶解度,溶液中K⁺与Cl-产生吸附,并最终以KCl晶体析出。结论 基于上述析出机理,优化构建了一套完井液配方,密度在1.10~1.50 g/cm³可调,与酸液配伍好,高温稳定性良好。 

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. Conclusion sBased 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.