Potential Development Study of Thin Interbedded Reservoirs Based on Detailed Reservoir Characterization and Classification Evaluation

Abstract

In the early development phase of Offshore Oilfield A, the field was developed using a sparse well pattern, large well spacing, and commingled production of long intervals. Upon entering the high water-cut stage, the field faced severe interlayer interference, prominent injection-production conflicts, rapid water cut rise, and accelerated production decline. There is an urgent need to clarify the distribution patterns of remaining oil and implement late-stage development adjustments. Results: (1) Building on advances in detailed characterization of thin interbedded reservoirs in the high water-cut stage of the Penglai Oilfield, a fine characterization technology for thin interbedded reservoirs was established based on sedimentary simulation constraints. Guided by the principles of "sedimentary constraints, hierarchical dissection, well-seismic integration, and model guidance," this technology achieves precise quantitative reservoir characterization. (2) By integrating macro- and micro-scale analyses of the geological, reservoir, and development characteristics of the A Oilfield, the reservoir classification system for thin interbedded reservoirs was optimized. A quantitative interpretation technology for high-salinity water-flooded layers was developed, enabling—for the first time—quantitative evaluation of the production performance of various reservoir types in thin layered reservoirs during the high water-cut stage. (3) The target recovery factor for Type I reservoirs was determined to be 46%–50%. Although currently in the "ultra-high water cut and ultra-high recovery" stage, the recovery factor under the existing well pattern is 39%, indicating significant potential for improvement (7%–11%). Type II and III reservoirs exhibit lower current recovery degrees and hold considerable potential. (4) Based on the subdivision and recombination of layers in thin interbedded reservoirs, further research was conducted on key technologies, including optimized deployment of horizontal wells based on the genetic architecture of main sand bodies, well pattern optimization for non-main layers, and secondary infilling techniques. This established an efficient adjustment model for the high water-cut stage of thin interbedded reservoirs in the A Oilfield. Field practice shows that the successful application of this development adjustment technology system has increased the initial productivity of oil wells in the A oilfield by 3-5 times and enhanced the recovery factor by 8%～12%. This system has provided crucial technical guarantees for the safe and efficient development of Bohai oilfields during the "13th Five-Year Plan" period and offers strong technical support for their medium-to-long-term development.