Loading...

Experimental Investigation of Fluid Placement and Diversion for Matrix Acidizing

Eghdam, Alireza | 2016

643 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48759 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Ayatollahi, Shahabaldin; Shad, Saeed
  7. Abstract:
  8. Acidizing efficiency depends on various factors such as formation properties, reservoir and stimulation fluid types and injection scenario. Among these factors, heterogeneity of reservoir’s formation (layered reservoirs and permeability variation versus depth) strongly affect acidizing performance. Accordingly, applying a reliable technique that distribute stimulation fluid uniformly is essential. The aim of carbonate matrix acidizing is to improve fluid flow specially in low permeability zones. Stimulation fluid cannot enter into the low permeability layer due to existence of high permeability layers which are in contact with low permeability ones. So, the stimulation fluid should be diverted to the zones which need Stimulation. In this study a chemical diverting agent, Viscoelastic surfactant is used. The performance of this diverting agent depends on its ability to divert acid between two zones with different permeability values. The higher permeability difference between zones, the more efficiency the VES will perform. In addition to diverting agent quality, its concentration and injection scenario are other two key factors affect in successfulness of operation performance. In this work, first of all the optimum concentration of VES is determined by rheology measurements and considering additives effects. Then, the impact of additives, viscosity build up during rock and acid reaction are investigated. After obtaining the optimum concentration for diverting fluid, acid flood test on single core is done to determine the maximum pressure build up. According to the single core test results, parallel acid flood tests for layers with different permeability values are performed. At the last stage, a new method is presented to eliminate the limitations of high permeability ratio layers. In the single acid flood experiments, critical injection rate hypothesis was investigated and its value was determined. Dual injection tests had a good performances in permeability ratios up to 6.2 but increasing this ratio failed the test. According to the new method presented in this work a test was done successfully with permeability ratio of 27. A new diverting agent is used in this study. The performance of diverting fluid was investigated by rheological study beside the acid flood in single and dual cores for first time and a road map designed for testing these kind of materials. Regarding of rheology measurement results, flooding in plugs bellow 4 inches were successful and also the limitations in permeability ratio in previous works are eliminated by multi stage method
  9. Keywords:
  10. Permeability ; Rheology ; Acid Divertor ; Permeability Ratio ; Parallel Injection ; Acid Additives ; Viscoelastic Surfactant (VES)

 Digital Object List

 Bookmark

No TOC