Permeability estimation from time-lapse seismic data for updating the flow-simulation model
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The key to increasing reservoir recovery is to provide accurate estimates of the permeable pathways (permeability, transmissibility) and the transmissibility of the barriers that control reservoir heterogeneity. The reservoir-engineering techniques (such as well testing, well logging and production data) supply the estimate of these properties in the reservoir region which is limited to well locations. Providing estimates of the permeability in the reservoir rocks located between the wells is the holy grail of reservoir engineering for history matching. Compared with all other engineering techniques, 4D seismic could play a unique role in providing the property of the reservoir at a good spatial coverage. In this thesis, the estimation of permeability, transmissibility, and the transmissibility multiplier, using 4D seismic, is addressed. First, current methodologies for permeability estimation were applied in synthetic and field examples. Based on the investigations performed, the permeability-estimation method was modified and adjusted to produce an improved result. Consequently, the estimates of permeability provided an introduction to the fast-track history-matching method. The proposed history-matching technique implies a simple and practical approach for quickly updating the simulation to improve the history-matching in the model. In following, the assessment of the uncertainties associated with the permeability estimation that involves using a variety of different attributes, using different time-lapse surveys, tuning effects and method assumptions, were performed. The uncertainties were tackled by addressing these issues; thus, the permeability result was further enhanced, and the uncertainty associated with the estimates was quantified. Next, the relationships between the quantitative estimates of connectivity and the 4D seismic signal were established. Two types of connectivity assessments using 4D seismic (hydraulic sand connectivity and barrier connectivity) were proposed, depending on the fact that 4D-seismic information is either pressure- or saturation-dominant. Accordingly, two types of attributes were introduced, the seismic connectivity attribute (SCA) and the Laplacian attribute. When applied to the Schiehallion field data, an interpretation approach is used to interpret pressure- and saturation-anomalies in frequent time-lapse seismic, using all available sources of data. Following this, a pressure-anomaly map is utilized for locating faults and compartments iii (using the Laplacian attribute), and a saturation-anomaly map is used to calculate the SCA. New approaches were chosen for estimating transmissibility and transmissibility multipliers, based on proposed attributes extracted from 4D seismic.