Reducing Reservoir Characterization Uncertainties and Improving Field Recovery through Four-Dimensional Seismic Technology: An Integrated Four-Dimensional Seismic Interpretation Workflow
Jie Zhang, Dez Chu, Ganglin Chen, Kelly Wrobel, William L. Soroka, 2011. "Reducing Reservoir Characterization Uncertainties and Improving Field Recovery through Four-Dimensional Seismic Technology: An Integrated Four-Dimensional Seismic Interpretation Workflow", Uncertainty Analysis and Reservoir Modeling: Developing and Managing Assets in an Uncertain World, Y. Zee Ma, Paul R. La Pointe
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More than one-half of the world's remaining hydrocarbon reserves are in carbonate rocks. Reservoir complexity and heterogeneity in carbonate reservoirs are commonly the main sources of uncertainty in reservoir models and thereby affect field recovery strategies. Four-dimensional seismic technology, which acquires three-dimensional seismic data over a producing field at different times, can provide valuable information on the reservoir changes induced by hydrocarbon production. This information can then be used to better understand the reservoir's complexity, heterogeneity, dynamic flow parameters, and production performance.
The application of four-dimensional seismic technology in carbonates is still in an early stage because of many challenges such as detectability and repeatability of four-dimensional seismic data. This chapter provides an overview of the workflow, describes more details through an application to a giant carbonate oil field located onshore Abu Dhabi, and emphasizes reduction of reservoir uncertainties.
The workflow consists of the following six steps: (1) rock physics analysis on the effects of fluid and pressure changes on the elastic properties of the reservoir rocks; (2) four-dimensional forward seismic modeling; (3) seismic acquisition geometry analysis, seismic data processing assessment, and postproduction processing data enhancement; (4) qualitative and quantitative four-dimensional seismic data analysis; (5) four-dimensional seismic updating of geologic models; and (6) reservoir simulation feedback using four-dimensional seismic data.
For any hydrocarbon field, a comprehensive understanding of its reservoir rocks, fluid movement, and aquifer dynamics is essential to maximize the hydrocarbon recovery and minimize the development cost. The process begins when a discovery is made and continues until the resources are depleted. This process involves the multidisciplinary integration of geologic, geophysical, and reservoir engineering data analyses and interpretations, which can include outcrop and core descriptions, subsurface geologic mapping and modeling (Ma et al., 2011), well-log analysis (Moore et al., 2011), three-dimensional (3-D) and/or four-dimensional (4-D) seismic data interpretation, and production history analysis (Devegowda and Gao, 2011; Heidari et al., 2011). The geologic details needed to properly develop or produce most hydrocarbon reservoirs greatly exceed those that were used to discover them. In this chapter, we concentrate on applying 4-D seismic data to this process, with the goal of reducing reservoir uncertainty.