【Introduction】

   Water flood technique is widely used in the development of oilfields in China. 87% of its reserves is developed by water injection. Now most of oilfields come into the stage of development with high water cut, the average water content over all oilfields in the country has reached 81.4%. Long practices demonstrate, that after the oilfields were put in water injection, the physical properties of reservoirs undergo great changes, which are dependent on different properties of reservoirs and injected water. The problems associated with determination of remaining oil distribution by well logging become complicated due to the changes in oil formation in the water flood process. This book contains 64 papers on these studies.