Abstract:

The conglomerate reservoirs inKaramay Oilfield have entered the development phase of high waterˉcut after forty years of water flooding. An accurate identification of waterˉflooded zones as well as a quantitative classification of wateringˉout level is the key and difficult issue to be considered in the adjustment of development strategy in this maturing oilfield. This paper documents a study that takes the conglomerate reservoirs in the Kexia Formation of the Liuzhong block as an example. It analyzes factors that affect the reservoir parameters by using the pressure coring data of three wells that were the focus of development adjustment in 2006 and by combining the actual geological characteristics of conglomerate reservoirs. It also selects logs that match well with the geoˉlogical characteristics and production pattern of the conglomerate reservoirs. Models for the interpretation of physical properties，lithology，water production rate，and water drive index of the Kexia Formation are established based on methods like cross plotting and multivariate linear regression. Three parameters，namely the water production rate，the oil saturation，and the water drive index，are chosen to be the main factors for aquantitative determination of wateringˉout level. Combining these factors with qualitative resistivityˉidentification chart for wateredˉout zones，the study offers rules and methods for qualitative identification of wateredˉout zones in this kind of reservoirs. The application of the method to the Kexia Formation yielded a coincidence rate of as high as 84.36%，well beyond the required accuracy. A set of technologies for quantitative identification of wateredˉout zones in conglomerate reservoirs is finally developed to improve the accuracy of wateredˉout zone identification.

Key words: waterˉflooded characteristic parameter, water drive index, quantitative identification, wateredˉout zone, Kexia Formation in the Liuzhong block, conglomerate reservoir, Karamay oilfield