Predicting the distribution of small faults in a hydrocarbon reservoir by combining outcrop, seismic and well data

Abstract

This paper investigates the possibility of identifying small faults in a hydrocarbon reservoir from spatial derivatives of seismic horizons (dip, azimuth, rate of change of dip), combined with well log structural data and analogue models. The analogue models include examples from the literature and a faulted surface constructed from Kilve beach, Bristol Channel, which represent typical surface attributes associated with small faults and artefacts produced by modelling. Well log structural data of good quality were integrated with the seismic data to study the 1D spatial distribution of subseismic faults and their expression on seismic horizons. The results suggest that dip and azimuth modelling can be useful, but the methods need to be combined to achieve reliable interpretations of the individual features. The rate of dip change has less potential to trace individual structures, unless the signal/noise ratio is very high. The ductile strain observed on seismic sections is, to a large degree, assumed to be produced by subseismic faults. The amount of ductile strain may be quantified by calculating the rate of dip change across curved seismic horizons. Exact predictions of fault densities are difficult because of the inaccuracies related to the modelling technique and the variability in fault and fold styles that occurs on a subseismic scale. Detailed dipmeter and core interpretation can be used to calibrate structural dip and spatial frequency of faults.

Structurally controlled hydrothermal dolomite reservoir facies: An overview

“…Modified from G. Davies (2001, unpublished data). to this preference: buoyancy (thermal density) drive into the hanging wall (Phillips, 1972), pressure-driven preferential flow to the upper hanging wall during faulttip propagation (Knipe, 1993), damage zone preference (Knipe et al, 1998), and increased fracturing in the upper hanging wall (Steen et al, 1998). This factor should be considered in drilling-site selection for HTD targets from 2-D or 3-D seismic data.…”

Geological controls on fault relay zone scaling

“…In suitable outcrops, fault tips can be observed directly, whereas in 88 seismic data there is an inherent resolution limit below which discrete fault geometries 89 cannot be imaged (Steen et al, 1998;Townsend et al, 1998). Therefore, outcrop 90 observations are used to develop simple criteria for identifying the location of fault tips.…”

Numerical experiments of fracture-induced velocity and attenuation anisotropy

“…Seismic wave propagation through fractures and cracks is an important subject in exploration and production geophysics, earthquake seismology and mining (Steen et al 1998; Nelson 2001). Fractures constitute the sources of earthquakes (Daub & Carlson 2010) and hydrocarbon and geothermal reservoirs are mainly composed of fractured rocks (Xu & Pruess 2001).…”