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Abstract The Bohai Sea possesses abundant heavy oil reserves, a significant portion of which is characterized by thin layers and complex oil-water systems. The development of these thin-layer heavy oil reservoirs faces two primary challenges: firstly, how to enhance well productivity to mitigate the high development costs inherent to offshore environments; secondly, how to improve recovery factors under conditions of a sparse well pattern to achieve the economic goal of "higher productivity with fewer wells." Consequently, targeting a typical Bohai Sea offshore heavy oil field featuring thin interbedded layers and multiple oil-water systems, technological innovation and field practice have been undertaken to explore an economically viable development strategy for such reservoirs. Field J exemplifies these challenges: thin individual layers (2-7m for main pay zones) necessitating numerous horizontal wells for layered development, numerous vertical sub-layers (5-8 sets) prone to premature breakthrough of injected fluids, and high in-situ oil viscosity (234-345 mPa·s) leading to low productivity under conventional methods. To address these issues, laboratory 3D physical simulation experiments were conducted to quantitatively study interlayer steam injection heating efficiency and steam chamber propagation. This was combined with reservoir engineering methods and numerical simulation to investigate balanced steam allocation techniques, followed by field trials, yielding significant insights for developing thin, multi oil-water system heavy oil reservoirs. Based on the aforementioned research, field trials were implemented, leading to key technological innovations: Firstly, physical simulation confirmed that, for vertical/deviated wells under various interlayer conditions, segmented steam injection significantly improves the uniformity of the steam intake profile across layers and enhances heating efficiency compared to blanket injection. Secondly, based on the principle of hydrodynamic similarity and using the interlayer heating radius equilibrium coefficient as an evaluation metric, a balanced steam allocation and control method for multi-layer heavy oil reservoirs was established. This method reduced the interlayer steam intake variation coefficient from 0.53 to 0.37 during steam injection and increased cyclic oil production from 42 m³/d to 55 m³/d. Thirdly, an enhanced recovery strategy was proposed: "initial CSS(6 cycles) followed by transition to a thermal-chemical composite steam drive after reservoir pressure decline, coupled with real-time allocation control." Numerical simulation indicates this strategy can improve the recovery factor by 3.4% and increase cumulative oil production by over 80,000 m³ compared to a fixed steam injection scheme. Currently,60 thermal recovery wells have been put into operation in the oilfield, using steam huff and puff segmented balanced steam injection development. Since its commissioning, the overall production of the oilfield has been stable, with an average daily production of 65 tons per well during peak periods. This research has successfully supported the development of the world's first offshore thin-layer heavy oil field with multiple oil-water systems. It establishes a novel development model: "Steam Stimulation in Offshore Heavy Oil Reservoirs with Multiple Oil-Water Systems Using Large-Spacing Deviated Wells," providing crucial technical guidance for the efficient development of offshore heavy oil resources.