Abstract: The invention relates to a method for characterizing a hydrocarbon reservoir comprising a gas cap (1) and an oil zone (2) with respectively Scwg and Scwo as the water saturation in each zone. The zone is invaded by gas either by gas injection, gas cap expansion or because of evolution of dissolved gases. In the method, the decrease in the initial water saturation Scwo in oil zone (6) during the displacement thereof by the gas is taken into account, the decrease being gradual down to Scwg which is distinctly below Scwo.

Abstract: A method and computer system for deriving and applying normal moveout phase and time shift corrections to seismic survey traces is disclosed. Normal moveout time-shift corrections are first applied to traces in a common midpoint (CMP) or common depth point (CDP) gather, based upon stacking velocity analysis applied to envelopes of the traces. One offset in the survey, preferably the maximum offset, is selected as the reference point; the NMO time shift at this reference offset is then selected as a reference NMO time-shift. The traces in the gather are each phase-shifted based upon iterated reference phase dispersion values at the reference offset, times the ratio of the normal moveout time-shifts for the trace in the gather to that of the reference offset (raised to a power). Semblance analysis is performed to identify, for each point in normal incidence time and thus for each reflective event, the optimum reference phase dispersion value.

Abstract: A system for producing a material balance solution for well patterns in a hydrocarbon reservoir is described that automatically optimizes the fluid allocation factors for each well used in determining the solution. The system automatically optimizes estimates for the allocation factors to be used in the material balance solution by randomly generating a first generation of allocation factor strings, each string in the generation assigning allocation factors to each of the wells in the reservoir. A fitness function value is determined for each of the strings by evaluating a fitness function, wherein the fitness function comprises the sum of the differences between computed and measured field pressures for each pattern, and the sum of the differences between target allocation factors and the allocation factors specified within the string for each well. A succeeding generation of allocation factor strings is produced according to a genetic algorithm.

Abstract: A method and apparatus for predicting distribution of reservoir permeability or porosity and pseudo relative permeability using well data and 3-D seismic data are disclosed, where a preferred first step in the method models the reservoir property of interest to provide model logs which are expressible as continuous curves of a reservoir property as a function of depth. The next step selects individual data points on the continuous curves traversing a reservoir layer and determines permeable trends for a multitude of column-like subvolumes which each enclose a portion of the selected data points. The subvolumes are then divided into a desired number of horizontal slices, with each slice containing a number of the model data points. An average value for the property in each slice is calculated, and the average values are plotted versus depth for each subvolume, thus providing a derived curve of depth versus the reservoir property.

Abstract: A method and apparatus for predicting barriers to fluid flow in a subterranean reservoir using well data and 3-D seismic data are disclosed, where a preferred first step in the method models petrophysical properties of the reservoir to provide model logs which are expressible as continuous curves of a reservoir property as a function of depth. The next step selects individual data points on the continuous curves, which traverse a subterranean layer, and assigns a flow or nonflow state to each data point based on comparing a threshold value of a reservoir property with the value predicted by the data point. The layer is divided into a multitude of subvolumes each containing a single data point, and then a connectivity factor, which considers multiple flow paths around each data point, is calculated for each subvolume.