FINE RESERVOIR CHARACTERIZATION AND ITS APPLICATION TO EARLY DEVELOPMENT OF AN OFFSHORE OILFIELD: A CASE STUDY FROM THE SAND BODY X OF BOZHONG A OILFIELD

The Neogene shallow-water deltaic reservoir, which bears many intercalations, changes quickly both vertically and horizontally in the Bohai Oilfield. Predicting the reservoir distribution and optimizing the location of horizontal wells need to be solved in the early stage of development in order to reduce the well number to the minimum. The shallow-water deltaic deposit in the Bozhong A oilfield is selected as an example in this case of study. According to the data of cores, logging and seismics, the deposits are divided into several genetic units under the guidance of high resolution sequence stratigraphy. In the study area, distributary channels, mouth bars and river sediments are well developed. The depositional sequence includes 1 short-term cycles and 4 ultra-short-term cycles, reflecting a progradational sequence as the sea-level decline to exposure, and then a retrogradational sequence as the sea level rising again to the flooding surface. According to the deposition pattern and sequence characteristics, 3 kinds of contact relationship of the composite sand body are identified. Moreover, single-channel sand body and distribution of interlayers are predicted. The sand body X is separated into three upon structures. Combining with the production characteristics of horizontal wells, suggestions are made for optimization of horizontal wells under the four development modes.