Treatment of faults in production simulation models

Abstract

This paper describes basic 'rules-of-thumb' that offer an indication of common uncertainties and pitfalls, as well as the analytical methods, data requirements and work elements required to replicate the impact of faults on fluid flow in production simulation models successfully. The first, and most important, stage in this modelling process is to ensure that an accurate structural interpretation is incorporated into the simulation model. In particular, that all fault linkages and cross-fault juxtapositions are taken from the seismic interpretation into the simulation grid. Fault rocks sometimes reduce the rate of cross-fault flow in which case it is important to account for this reduction in flow within simulation models. This is best achieved if databases of fault rock properties, measured from the field of interest or nearby similar reservoirs, are up-scaled to calculate fault transmissibility multipliers. It is sometimes necessary to consider not just the single-phase permeability but also the capillary pressure and relative permeability characteristics of the fault rocks present. Finally, all the relevant static and dynamic data must be appraised critically. However, the interpretation of such data is usually non-unique and misinterpretations can create errors in the production-related fault seal analysis. Where these basic guidelines are followed, it has been our experience that the project time required to achieve a history match of production data is dramatically reduced. In addition, as the history match is more geologically reasonable, the model is often more reliable for predicting the long-term behaviour of the reservoir. This gives confidence in the model's forecast to guide development planning and day-to-day field management decisions.

Reservoir compartmentalization: an introduction

“…Hempton et al 2005); or a combination of similar mechanisms (e.g. Fisher & Jolley 2007 and references therein). The paper by Scott et al describes the most recent evolution of ideas on Pierce.…”

“…Thus, it is not unusual for subsurface teams to place too much emphasis on one aspect of the evidence, or to make early assumptions that bias data acquisition, analyses and interpretations later on. For example, Fisher & Jolley (2007) point out that non-existent faults or improbable fault seal capacities might be invoked to explain variable petroleum contacts and dynamic fluid/pressure behaviour -when an alternative or combination of factors, or other unrelated explanations might be more appropriate for the data (e.g. hydrodynamic tilting of petroleum contacts, Tozer & Borthwick).…”

Improvements to the fuzzy mathematics comprehensive quantitative method for evaluating fault sealing

“…Large faults, which form the boundaries of oil and gas fields, can generally control hydrocarbon accumulation (Agosta et al 2012;Allan 1989;Balsamo et al 2010;Bouvier et al 1989;Braathen et al 2009;Brogi and Novellino 2015;Choi et al 2015;Collettini et al 2014;Fisher and Jolley 2007). However, small faults generally separate oil and gas, resulting in an increase in well spacing that poses challenges in oil and gas exploration.…”

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

“…Characterizing fault properties and understanding fault impact on flow paths and reservoir dynamics through modeling remain key issues for optimizing production and exploration strategies (Fisher and Jolley, 2007). However, these efforts are hampered by the inherent difficulty of describing structural complexity and petrophysical heterogeneity of entire fault zones based on spatially constrained outcrops representing a limited range of scales compared to those observed in the subsurface, and a lack of unified classification systems adapted to the needs of 3D modeling and simulation (Braathen et al, 2009).…”

“…Initial attempts to implement effects caused by petrophysical heterogeneities known to occur in faults involved heuristic iterative adjustment of fault plane transmissibility in the simulation model during history matching of dynamic well data. This often produces geologically unrealistic results, and runs the danger of compensating for effects within the simulation model which are Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/cageo not related to faults (Fisher and Jolley, 2007).…”