Study On Self - Steering Acidic Acidic Acid Production In Carbonate Horizontal Wells

In recent years, VES self-diverting acid has been more and more used in horizontal well acidizing operation for carbonates due to its excellent diverting effect, low damage and wide application conditions. The field operation, however, often relies on experience. For the key questions such as what’s the fluid placement difference between HCl and VES self-diverting acid, whether wormhole gets enough penetration distance, we have no answer.This study is based on the property of VES self-diverting acid, combining with the characteristic of acid placement and horizonatal well acidizing in carbonates and considering the effect of viscosifying behavior of VES self-diverting acid to the amount of inflow into reservoir to form the horizontal well VES self-diverting acid acidizing model for carbonates. Through the study of the thesis, mainly gets the following results and understanding:(1) The relationship between viscosity of the reacted self-diverting acid and pH value and the Ca mass fraction through laboratory experiment is studied, based on which builds the mathematic model of diverting behavior.(2) The model of diverting behavior is coupled with TSC model to build wormhole propagation model for self-diverting acid. Simulation result shows that wormhole propagation will be affected by viscosifying action of VES self-diverting acid, dissolution pattern, acid volume and optimum injection velocity will also be affected by heterogeneity.(3) The wormhole propagation is introduced into the exsisting horizontal acid fluid placement model, then combine stimulation forecast model to form the horizontal well VES self-diverting acid acidizing model for carbonates. Simulation result shows that damage skin distribution, horizontal interval length, injection displacement and injection volume will affect acidizing result of VES self-diverting acid. Suggestions on necessity of using VES self-diverting acid and operation parameters in VES self-diverting acid acidizing design are given.The research result of this paper is valuable especially for improving the effectiveness of horizontal well VES self-diverting acid acidizing design and scientific guidance for field application of VES self-diverting acid in horizontal well matrix acidizing.