Architecture characterization and completion mode selection for the reservoirs of distributary channel of shallow-water delta

To increase the single-well production rate and oil reservoir recovery factor of BZ19-4 Oil field, the reservoir architectures of underwater distributary channel of shallow-water delta were dissected and the completion modes of horizontal wells were investigated in this paper. Based on the seismic, core, mud log and logging data, the architecture of distributary channel of shallow-water delta in the Lower Member of Minghuazhen Formation in the study area was characterized layer by layer with the vertical stage as the focus according to the architecture mode. Then, the allocation relationship model between the horizontal well trajectory and the aggradation layer was established on the basis of the architecture characteristics. And finally, combined with the characteristics of narrow and thick banded sandbody, the well completion mode was optimized. It is indicated that underwater distributary channel of shallow-water delta can be divided into three architecture layers, i.e., complex channel, single channel and aggradation body inside the channel. The complex channel can be identified on the basis of seismic data, and it is 400-1 100 m wide and 10-40 m thick. The single channel can be identified by using combination mode analysis and boundary identification, and it is 250-350 m wide and 2-9 m thick. The internal architecture unit of the single channel can be identified by means of rock electric characteristic investigation and mode cognition, and two architec-ture units are identified, including aggradation body and aggradation layer. The upper part of shallow-water delta aggradation layer is connected effectively with its underlying thick reservoir in the completion mode of horizontal well with deep-penetration perforation. It provides the suggestions for the stimulation of oil wells.