Measurement of Reaction Rate of Gelled Acids and Calcite with the Rotating Disk Apparatus

Yunhu Liao,Hao Liang,Dezheng Zhang,Jianfeng Peng,Yunlei Gong

doi:10.4236/nr.2017.88035

Abstract

An investigation has been made to study the reaction kinetics of gelled acids with calcite using a rotating disk apparatus. The rheological experiments revealed that all gelled acids behaved as non-Newtonian shear thinning fluids. With the rotating disk apparatus, the reaction kinetics parameters, activation energy, and effective diffusion coefficients were determined. It was found that the reaction of gelled acid with calcite was mass transfer limited at low polymer concentration and moving toward surface reaction limited at higher polymer concentration. And the diffusion rate marginally decreased, with increasing the polymer concentration.

Highlights

In carbonate formations, acidizing treatments provide a means of removing the damage from the wellbore area and an opportunity to improve the near-wellbore permeability
It was found that the reaction of gelled acid with calcite was mass transfer limited at low polymer concentration and moving toward surface reaction limited at higher polymer concentration
The reaction of gelled acids with calcite in the rotating disk apparatus is shown in Equation (1): CaCO3 + 2H+ → Ca2+ + CO2 + H2O

Summary

Introduction

In carbonate formations, acidizing treatments provide a means of removing the damage from the wellbore area and an opportunity to improve the near-wellbore permeability. Gelled acids, which have been widely used to increase the viscosity of acid in the formation, can enhance diversion and achieve deep acid penetration and longer fractures. The reaction rate is used to determine the distance that acid can penetrate from the wellbore at a given pumping rate before it is completely spent [1] [2]. The reaction of gelled acids with calcite in the rotating disk apparatus is shown in Equation (1): CaCO3 + 2H+ → Ca2+ + CO2 + H2O (1). The slowest step controls the overall reaction rate [3]

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Conclusion