Cross-fault sealing, baffling and fluid flow in 3D geological models: tools for analysis, visualization and interpretation

Abstract

The effective computation and visualization of cross-fault sealing or flow, and parameters that infer or control that distribution, is a key step in the production of more reliable exploration and production simulation models. A better understanding of the impact of fault-related flow or baffling through visualization can lead to the development of more robust and useful geological models that better define the likely range in flow behaviour. A range of visualization tools are available, from the traditional fault plane juxtaposition map to the vector visualization of cross-fault fluid flux. Each tool has its applications and limitations.In this contribution we discuss the application of these different techniques and highlight situations where these are particularly successful. A number of existing visualization approaches will be reviewed and improvements to those techniques are shown. A series of existing property visualization techniques are critiqued, such as the imaging of shale gouge ratio (SGR) and fault transmissibility multipliers (TMs) on the fault faces, both of which are limited in their ability to act as a proxy for cross-fault fluid flux in many circumstances. Fault rock property visualizations, such as hydraulic resistance and fault transmissibility, are presented. More direct and hence more powerful indications of probable cross-fault fluid flux are also described, such as the effective cross-fault transmissibility (ECFT) and the effective cross-fault permeability (ECFP). These static proxies for cross-fault fluid flux are compared against back-calculated and visualized cross-fault fluid flux values derived from either streamline or full flow simulation data. The ECFT is shown to provide a useful and rapid indication of likely fluid flux from the static model; however, the direct imaging of cross-fault fluid flux derived from simulation results allows for a far better understanding of how the faults have contributed to the reservoir flow simulation result.Visualizations of the fault- and flow-related properties: (a) on the fault face; (b) in the grid cells adjacent to the fault face; (c) as vectors; or (d) as fault-wide summations, all provide useful insights for different parts of the reservoir evaluation workflow.This contribution highlights a series of new and efficient techniques to image and hence improve the understanding and modelling of fault sealing in both exploration and production settings.

The value of fault analysis for field development planning

“…17). No significant difference in the distribution is 306 apparent between the fault rock Vclay content when calculated using either SGR (Yielding, 2002) or ESGR 307 (Freeman et al, 2010), with a weighting factor of 1.5, as a fault rock Vclay prediction algorithm. A more 308 detailed analysis of the Vclay distribution on the fault plane reveals that the ESGR algorithm predicts a 309 more discrete distribution of Vclay, compared to the SGR algorithm (Fig.…”

Fault seal behaviour in Permian Rotliegend reservoir sequences: case studies from the Dutch Southern North Sea

“…Ideally, fault properties such as permeabilities and entry pressures based on core data are used for these predictions, but such data are typically not available due to the lack of core material. In areas and intervals with a higher variability in N/G ratios, the maximum hydrocarbon column height is typically estimated based on the fault displacement and clay content of the host rock using the SGR algorithm (Bretan et al 2003) or comparable type of transformation (Lindsay et al 1993;Yielding et al 1997;Yielding 2002;Freeman et al 2010).…”

Hydrocarbon accumulation in the northwest Chaluhe Fault Depression, Yitong Basin, North China

“…Several methods exist to analyse the sealing capacity of faults in sedimentary basin. Most fault seal algorithms, such as the shale gouge ratio, determine the sealing capacity of clay smearing faults using simple relations between fault displacement, thickness of the clay source bed or stress state of the fault zones (Yielding et al 1997;Freeman et al 2010). In this study, the positive pressure of the fault surface is calculated to study the fault vertical sealing property, based on the following formula (L€ u et al 1996):…”