Well Placement, Cost Reduction, and Increased Production Using Reservoir Models Based on Outcrop, Core, Well-log, Seismic Data, and Modern Analogs: Onshore and Offshore Western Trinidad
Grant D. Wach, Christopher S. Lolley, Donald S. Mims, Clyde A. Sellers, 2004. "Well Placement, Cost Reduction, and Increased Production Using Reservoir Models Based on Outcrop, Core, Well-log, Seismic Data, and Modern Analogs: Onshore and Offshore Western Trinidad", Integration of Outcrop and Modern Analogs in Reservoir Modeling, G. Michael Grammer, Paul M. “Mitch” Harris, Gregor P. Eberli
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Fluvial-estuarine channel complexes are significant producing reservoirs both onshore and offshore western Trinidad. These channel complexes are notoriously difficult to correlate in the subsurface. Numerous permeability baffles and barriers create complex reservoir heterogeneities that can result in significant bypassed hydrocarbons if the geometry and architecture of the channel bodies are incorrectly identified and not correlated in a rigorous sequence-stratigraphic framework.
Outcrops of tidally influenced nonmarine channel complexes and modern deposi-tional analogs are used to determine architectural elements and bounding surfaces that impact reservoir continuity and heterogeneity, thus, highlighting subsurface correlation pitfalls. These elements and surfaces that are established from the outcrops are used for the examination of cores, well-log, and seismic data of strata deposited in analogous depositional systems.
The subsurface and the outcrop geologic models are used in two reservoir-modeling scenarios: first, to refine subsurface reservoir models for horizontal well placement, leading to a more effective depletion strategy for the reservoir, and second, the modeling of a field simulation using outcrop exposures of a channel complex as a producing analog. The result of the simulation runs was a similar recovery from the “field” with far fewer wells, showing that substantial cost reductions are possible in drilling and completions, operations, and future well and field abandonment, including the potential risk and costs for environmental remediation.
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Building robust 3-D reservoir models is a major challenge that requires incorporation of geologically defined input parameters. This publication provides an overview of current approaches used in the development of geologically constrained and integrated reservoir models. Each of the 18 papers addresses various stages in the process of creating a reservoir model through the development and incorporation of an analog, extracting the quantitative input parameters on lateral and vertical variability, and the development and modification of a 3-D reservoir model based upon geologically constrained data. This applied volume is divided into two sections. The first is a set of papers illustrating the value and methodology of acquiring geometrical data on the lateral and vertical distribution of reservoir facies, within a sequence stratigraphic framework, using both outcrop analogs and detailed study of modern depositional systems. The second section includes both case studies where outcrop and modern analog data have been incorporated into subsurface reservoir models, as well as papers that illustrate recent advances in simulation and geostatistical methodologies. Together, the two sections provide a comprehensive look at integrated reservoir modeling.