Abstract: Abnormal pressure is one of the critical issues in oil-gas reservoir formation, and its development range indicates the main
direction of oil-gas migration and thus is important to the prediction of favorable exploration areas. Based on a case study in the
Dongying sag, a new method for the prediction of abnormal pressuredevelopment range is established by using hydrocarbon
geochemistry. First, combined the measured pressure with the geophysical data, the present pressure development characteristics in the
Dongying sag were analyzed to determine the division and scope of pressure systems. Second, according to the statistical features of
hydrocarbon geochemical parameters within the pressure systems, their relationship with pressure development were analyzed. Results
show that the sterane C29S/R, sterane C27/C29 and Pr/Ph ratios are positively correlated to pressure coefficient in abnormally high
pressure zones. Geochemical parameters were screened for the division of abnormally high pressure zones and the correspondingvalue
rangeswere determined. This new methodology was further applied in the Dongying sag. Results show that the development scope of
abnormally high pressure is larger than the present abnormally high pressure zone either horizontally or vertically. The main extension
areas locate in the slope zone. This provides new important information for predicting favorable exploration targets.

Key words: abnormallyhighpressure, developmentrange, geochemistry, characterizationparameters, accumulationstages, DongyingSag