Diagenetic Field Analyses And Reservoir Quality Predictions In The Middle-Shallow Strata Of North Songliao Basin

Considering effects of time, temperature, fluid medium and pressure on diageneses, Based on the old Diagenetic Modeling System, this paper modified and improved its geologic model, and recompiled the modeling system. This paper completed the diagenetic numerical modeling and the diagenetic field analyzes to the Middle-Shallow Strata of North Songliao Basin using the new modeling system.The results of field analyze of the Middle-Shallow Strata of North Songliao Basin showed that the mature area of organic matter of K2qn1 centralizes in the Central Depression. The mature area of organic matter of K2qn1 came into great quantity hydrocarbon generation from the K2qn, and overpressure relief was happened. The reservoir of K1q4 and K1q3 is between middle diagenetic phase A1 and middle diagenetic phase A2 at deep area, and its diagenetic facies were dissolution facies and dissolution and cementation facies at that time, and secondary pores developed. On the side, tectonic movements were intensive, and developed lots of faults, and petroleum accumulated extensively of Fu-Yang Reservoir at that time. The overpressures of K2qn1 reached to the limited level and leaked off, and Fu-Yang Reservoir petroleum accumulated extensively again at K2m, when the source rocks and reservoirs were developed .The diagensis intensity at present keeps the state of K2m, and the reservoir of K1q4 is between early diagenetic phase and middle diagenetic phase A2, and have good quantity, while and the reservoir of K1q3 is middle diagenetic phase B at deep area, whose reservoir quantity is worse.Reservoir quantity is mainly controlled by sedimentary facies and diagenses. Reservoir porosity and permeability prediction models were established on the base of considering the two the factors, and the reservoir quantity of K1q4 and K1q3 are predicted. The average error between measured and predicted porosities is 2.78% on condition that the average pore-fillings of the reservoir are 16%. Base on recounting the reservoir porosity and permeability data of Fu-Yang Reservoir, the limited porosity and permeability of commercial reservoirs of Fu-Yang Reservoir are determined and the effective reservoir areas are predicted. The results show that most of the reservoir of K1q4 and K1q3 develops effective reservoir, and the reservoirs at the deep area in Qijia-gulong depression and Sanzhao depression lost commercial value because of bad quantity.