The Accurate Reservoir Characterization Of The Fluvial Sandstone And The Distribution Of The Remaining Oil In North Dagang Oilfield

The complicated fault- blocks fluvial reservoir in the north Dagang Oilfield was taken as the study object in this thesis. Multi-discipline such as reservoir geology , geophysics , reservoir engineering, modern oil well testing and indoor experiments were integrated to develop a set of research ideas and technologies on the remaining oil distribution in the complicated fault- block, which will offer reference to the similar research.. The main understanding and conclusions are as follows: 1. The accurate isochronostratigraphic correlation was carried out according to the characteristic of the fluvial reservoirs in this area, while various correlation methods were adopted for the comparative depositional types. Five sandbody gradual-changing types and correlation models were summarized. 2. Eleven kinds of microstructure types were developed based on systematic study, which resulted from the differential compaction and tectonic stress after depositional period. Meanwhile the distribution mechanism of the remaining oil was studied by the hydrodynamic method and numerical simulation. 3. The fault seal property was studied combined with static geological data, reservoir engineering and dynamic testing method, which led to six types of fault models on micro-fault sealing property and the study approaches and technologies for the quantificational study of fault seal property. The systematic study on fault sealing property has not been searched in references. Some helpful probes have been done in this study. 4. The reservoir depositional microfacies, reservoir architecture and the geometry characteristic of the sand body are analyzed systematically; meanwhile, the rock -electrical characteristic of different sedimentary body,the channel lateral migration direction and the reservoir horizontal distribution are researched. At the same time, study of the heterogeneity of the layer-in, interformation and horizontal and its controlling to the underground fluid movement are also carried on. 5. Based on previous study, reservoir flow units are closely analyzed and initially include the dynamic testing data into the classification criteria, of which made the criteria more reasonable. Four types of flow units in the study area are identified, furthermore, the relationship between petrophysical facies and flow units are discussed. 6. The alteration of the reservoir and fluid property after water injection are studied systematically, of which indicate that the pore-throat size,ratio and micro heterogeneity,porosity and permeability altered. The mechanism and formation of the reservoir alteration are analyzed from the point of the basic reservoir characteristic and the physical and chemical function between the injection water and formation. Using the fractal dimension theory to study the change of the well-logging before and after injecting water. 7. Utilizing the technology of facies-constrained modeling, 3D visualized geological model is set up. According to field data, several realizations have been selected to make the geological model approach the underground geological body in the most part. 8. The research on remaining oil during the late stage of oilfield development in this thesis is comparatively systematism at present. According to the real reservoir state of the working area, geological model is simplified, and proposed that the main factor of remaining oil forming include reservoir and development no-balance. Quantitatively research on distribution form and potentials of surplus oil are carried out from the view of macroscopy and microcopy .