Abstract: After the offshore heavy oil field with complex fluvial facies enters the middle and late stage of development,influenced by many oil-bearing series,serious interlayer heterogeneity and large viscosity difference,the distribution of remaining oil is more complex,many problems gradually exposed,such as prominent injection production contradiction,control reserves of single well are too high,large difference between interlayer and plane reserve production,fast comprehensive water cut rise,fast production decline,etc.It is necessary to carry out overall infilling to improve oil recovery.Due to unclear development time,large well spacing,cluster pattern and other development characteristics of offshore heavy oil field,the whole infilling faces many technical difficulties.By taking Bohai A oilfield as an example,starting from the reservoir engineering and key drilling and production technologies of offshore heavy oil integral infilling,the whole infilling technology system of offshore heavy oil including micro displacement mechanism of non-linear seepage,quantitative prediction of remaining oil distribution in large well spacing combined production,and multi-platform drilling approaching wellbore monitoring method was obtained.Through application of comprehensive adjustment in Bohai A oilfield,the average oil recovery rate was greatly increased.