Diagenetic Field Analyses And Reservoir Porosity Predictions On Shahejie NO.3Member And NO.4Member In Damintun Sag

Today, because of the reduced shallow-layer petroleum exploration targets and thedecreasing oil production, a growing number of petroleum explorations have been directing atsubtle traps in deep layer. Howerver, reservoir quality becomes poorer during being burieddeeply with higher temperature and pressure. Therefore geologists are eager to make clear thereservoir quality and favourable reservoir distribution in deep layer. We attempt to usediagenetic modeling technology, analyze diagenetic field of Shahejie N0.3Member and N0.4Member in Damintun Sag, and meanwhile predict rservoir quality and different reservoirdistribution, which are hoped to guiding next exploration.Diagenesis is one of the important factors which controls the forming and distributing offavorable reservoirs. Through diagenetic field analysis, we can know whenever the diageneticphase and diagenetic facie of any layer and any area. Today’s diagenetic field analysis resultof Damintun Sag has been shown as follows.At Rong Shengpu Subsag the bottom part ofShahejie N0.4Member is middle diagenetic phase B with tight compaction facie, other partsare middle diagenetic phase A2with dissolution and cementation facie, reservoir quality ispoor. The bottom part of the fourth member of Shahejie N0.3Member is among middlediagenetic phase A1and A2with good reservoir quality. Diagenetic intensity of other parts ofShahejie N0.3Member are small, which are between early diagenetic phase B and middlediagenetic phase A1with dissolution facie and good reservoir quality.Two main factors of always influencing Reservoir quality are sedimentary facies anddiagenesis. Base on sedimentary facies, different sedimentary facies’ reservoir porosityprediction models of Shahejie N0.3Member and N0.4Member were established. As thepredicting result showed, the reservoir porosities of the fourth member of Shahejie N0.3Member is bigger than14.0%, and Shahejie N0.4Member is less than12.0%in which theslope area is better. Finally, Reservoir of Shahejie N0.3Member and N0.4Member weredevided into two kinds, Ⅲ kind is the favorable reservoirs for deep-layer petroleumexplorations.