Acknowledgements
This research is supported jointly by the Liaohe Oilfield Branch Company, PetroChina, the China Natural Science Foundation (Nos. 40772121, 40172066 and 40314141) and China National 973 Projects (Nos. 2009CB219302). Colleagues of the Liaohe Oilfield Branch Company enthusiastically helped us with data and sample collection. It would have been almost impossible for us to finish this article without them. We would also like to deliver our appreciation to Dr. K. Hari for modifying the manuscript word by word.