The integrative research of 3D geological modeling and reservoir numerical simulation
With the rapid development of computer, the integration research of geological modeling and numerical simulation is more and more emphasized in oilfield. In this paper, the flow mathematical model is established, which considers starting up pressure gradient for low permeability reservoir. Based on the research of the geology characteristics, fine stratigraphic correlation and sedimentary facies, the 3D geological model is established through integrated research considering geology and reservoir, including facies model, oil saturation model, porosity model, permeability model and NTG model. Then the remaining oil distribution was calculated through fine reservoir simulation. Based on history match, the distribution of remaining oil is analysed through the research of deposition facies and flow layer, which can be used for reference on oilfield development potential adjustment and scheme design.
Key factors of remaining oil distribution of the lowest permeable sandstone reservoir and favorable area evaluation
According to characters of reserves' employ in the lowest permeable sandstone reservoir,the dynamic production target was used to classify the producing tract and the key factors of remaining oil distribution through combination of dynamic and static behaviors were analyzed.On the basis of the study,the favorable district by the quantitative analysis was determined by the fuzzy set theory.Through the analysis of dynamic and static behaviors about Zhuang 74 fault block in Wuhaozhuang Oilfield,sedimentary microfacies,microstructure and heterogeneity are the key factors of remaining oil distribution of the lowest permeable sandstone reservoir.The sedimentary microfacies takes on the strongest effect.Microstructure is moderate,and heterogeneity is small.In middle fan,the braided channel is the best microfacies,and channel edge is too narrow to make hole.And lobe is the potential microfacies.Two-type microstructure mode of double convexity mode and double nose mode,and the coefficient of permeability variation,which is from 0.3 to 0.9,are taken account into tapping remaining oil potentials.Five sand members were taken for example to evaluate quantitatively and the favorable area was indicated using the fuzzy set theory and the analysis of the key factors of remaining oil distribution.Through back-to-back test,the remaining oil in the lowest permeable reservoir was studied by the method.The results show that it is practical and the good effect is provided.
Methods for Increased Accuracy in Numerical Reservoir Simulators
The use of 2-point upstream weighting of fluid mobility is proposed as an alternative to the generally employed single-point approximation. Use of the 2-point formula results in the reduction of both numerical dispersion of flood fronts and the sensitivity of predicted areal displacement performance to grid orientation. Stability analysis provides the time step limitation for control of solution oscillations. This, together with limitations for control of overshoot and truncation error, provides a practical basis for the automatic selection of time steps. (18 refs.)