Faults and fault properties in hydrocarbon flow models

Abstract

The petroleum industry uses subsurface flow models for two principal purposes: to model the flow of hydrocarbons into traps over geological time, and to simulate the production of hydrocarbon from reservoirs over periods of decades or less. Faults, which are three-dimensional volumes, are approximated in both modelling applications as planar membranes onto which predictions of the most important fault-related flow properties are mapped. Faults in porous clastic reservoirs are generally baffles or barriers to flow and the relevant flow properties are therefore very different to those which are important in conductive fracture flow systems. A critical review and discussion is offered on the work-flows used to predict and model capillary threshold pressure for exploration fault seal analysis and fault transmissibility multipliers for production simulation, and of the data from which the predictions derive. New flow simulation models confirm that failure of intra-reservoir sealing faults can occur during a reservoir depressurization via a water-drive mechanism, but contrary to anecdotal reports, published examples of production-induced seal failure are elusive. Ignoring the three-dimensional structure of fault zones can sometimes have a significant influence on production-related flow, and a series of models illustrating flow associated with relay zones are discussed.

Role of Faults in Hydrocarbon Leakage in the Hammerfest Basin, SW Barents Sea: Insights from Seismic Data and Numerical Modelling

“…Nonetheless, the scale and detail of such complex deformation zones is beyond the capabilities of basin modelling studies, and usually, fault zones are simplified and modeled as boundary or volume elements [48,64]. Boundary element faults have no volume, and flow through them is assumed to be instantaneous.…”

“…In our model, faults are assumed to be poorly conductive if FCP exceeds 50 MPa and conductive with FCP values less than 0.1 MPa. The FCP and permeability pairs have been assigned to modeled faults from empirical fault core measurements by [64][65][66][67]. We tested the model sensitivity by running several scenarios with closed faults, as well as with varying FCP and permeability definitions.…”

A method for generating volumetric fault zone grids for pillar gridded reservoir models

“…Limitations related to modeling conventions, grid types, grid resolution and computational cost further constrain the level of detail that can be included in fieldsized simulation models. The pragmatic solution to these issues has been to simplify the way in which faults and fault properties are implemented in geo-and simulation-models (Manzocchi et al, 2010(Manzocchi et al, , 2008.…”

Improving geological and process model integration through TIN to 3D grid conversion

“…Some of these BGS groundwater modeling efforts contain elements of model integration (Hughes et al, 2011). There has been a tendency in the recent past to use a simplified form of the geology within mathematical process models, but there is a growing need to honor geological complexity such as faulting or discontinuous units (Blessent et al, 2009;Manzocchi et al, 2010;Kessler et al, 2009). …”