--> Exploring Multi-Scale Heterogeneity of Braided-Fluvial Reservoirs: Implications for Reservoir Performance

AAPG ACE 2018

Datapages, Inc.Print this page

Exploring Multi-Scale Heterogeneity of Braided-Fluvial Reservoirs: Implications for Reservoir Performance

Abstract

Stratigraphic variability and internal lithological heterogeneity of fluvial deposits affects their static and dynamic connectivity. To explore the multi-scale heterogeneity of braided-fluvial reservoirs, multiple well-exposed outcrops in Delta County, Colorado are used to characterize the geometry, stacking, and internal heterogeneity of fluvial architectural elements. Georeferenced UAV- (Unmanned Aerial Vehicles) based photogrammetry models, detailed measured sections, thin-section petrography, and core data provide dimensional, lithological and spatial data to explore the architectural complexity and facies relationships. This information is used to condition two-dimensional (2-D) and three-dimensional (3-D) geologic analog reservoir models of the braided fluvial deposits.

Lithological and petrophysical models are used to assess the impact of varying scales of heterogeneity on reservoir performance and fluid flow. Large-scale heterogeneity is related to the architectural-element (channel-complex) stacking and dimensions. Small-scale heterogeneity is related to internal variability such as lateral and frontal accretionary bar-set units, sedimentary structures, grading beds, and lithofacies juxtapositions. Large- and small-scale heterogeneity is evaluated using three-dimensional (3-D) geologic models conditioned from outcrop to capture the heterogeneity and petrophysical properties of the fluvial reservoir rock. The two-dimensional models use a single production and injector well pair while the three-dimensional models use a 5-spot pattern, a single injector surrounded by four producing wells. Both model types are dynamically simulated over 30 years for black oil and gas condensate production for both the large- and small-scale heterogeneity models to assess uncertainty on primary and secondary recovery stages at subsurface conditions via experimental design.