The 1

st

and 2

nd

Members of Shahejie Formation in A oilfield in Shijiutuo uplift

Bohai Bay Basin

are rare proli-fic thick reservoirs with complex lithologies.Six lithologies are identified

mainly including limy sandstones

oolitic dolomites

dolomitic sandstones.There are various factors challenging reservoir description of the A oilfield

including complex lithologies

poor quality of seismic data

and sparse appraisal wells

large difficulty of fan delta reservoir description

and poor understanding of reservoir spatial distribution.This paper applied a well-logging and seismic comprehensive method

i.e.‘four step’ method

using ECS logging

core and seismic data.It consists of reservoir rock typing based on sedimentary facies

sedimentary modeling based on paleo-geomorphy restoration

reservoir framework reconstructing based on fine isochronous stratigraphy and reservoir prediction based on facies constraints.By using this four step method

sandbodies of 5 phases are identified and mapped in the 1

st

and 2

nd

Members of Shahejie Formation.In addition

good-quality reservoirs are predicted by using seismic technique

and 9 new development wells are proposed for emplacement on the Ⅰ-2 sand body with type Ⅰ reservoirs.This ‘four step’ method is very useful in estimating producible oil reserves

layer division

and well pattern optimization in similar oilfields.