EFFECT OF LONG-CORE ACID FLOW TESTING ON OPTIMIZATION OF SANDSTONE ACIDIZING DESIGN

Acid core flow testing,which core is typically short core plugs,is a common method for studying sandstone acidization.In this study,The long core plug is used in acid core flow testing.The flow testing results with long core show that the pad chlorhydric acid and lower concentration fluorhydric acid are useful to improve acidization effectiveness.Analysis of spent acid indicates that the setting of hydrated silica will be produced during acidizing under high temperature conditions.However,according to short core acid flow testing,higher concentration acid is helpful to increasing permeability.Comparing the testing results of long core and short core,the conclusion has been obtained that acidizing design based only on short core studies is misleading.This paper also gives an introduction to the effectiveness of sandstone acidizing based on long core acid flowing testing by several field examples.