The tectonic fracture modeling of an ultra-low permeability sandstone reservoir based on an outcrop analogy: A case study in the Wangyao Oilfield of Ordos Basin, China

Abstract

Due to inherent limits of data acquisition and geophysical data resolution, there are large uncertainties in the characterization of subsurface fractures. However, outcrop analogies can provide qualitative and quantitative information on a large number of fractures, based on which the accuracy of subsurface fracture characterization can be improved. Here we take the tectonic fracture modeling of an ultra-low permeability sandstone reservoir based on an outcrop analogy, a case study of the Chang6 1 1 An outcrop at the edge of the basin is a suitable analog for the reservoir, but the prerequisite is that they must have equivalent previous stress fields, similar final structural characteristics, relative timing and an identical depositional environment and diagenesis. The relationship among fracture density, rock type and bed thickness based on the outcrop is one of the most important fracture distribution models, geometry and scale, also should be described and measured in the outcrop, and can be used together with structure restoration and single well fracture density interpretation to guide fracture intensity prediction on bed surfaces and to constrain the construction of the 3D fracture geometry model of the subsurface reservoir. The application of the above principles shows the outcrop-based tectonic fracture models of the target ultra-low permeability sandstone reservoir are consistent with fractures inferred from microseismic interpretation and tracer tests. This illustrated that the fracture modeling based on the outcrop analogy is reliable and can reduce the uncertainty in stochastic fracture modeling.The tectonic fracture modeling of an ultra-low permeability sandstone reservoir based on an outcrop analogy:of Ordos

Use of Outcrop as Substitute for Subsurface Shale: Current Understanding of Similarities, Discrepancies, and Associated Challenges

“…Zhao et al used outcrop-based tectonic fracture models for an ultralow permeability sandstone reservoir and found consistency with fractures inferred from the microseismic interpretation and tracer tests. Becker et al also found a good correlation of outcrop fracture characteristics with subsurface results for a gas-producing tight carbonate reservoir in Germany, which could reduce uncertainties in reservoir characterization during field development and well planning.…”

“…19 The prerequisite is that the outcrop formation must have equivalent previous stress fields besides the final structural characteristics, relative timing, identical depositional environment, and diagenesis similar to the reservoir. 132 subsurface fractures. 123 On this basis, Ukar et al 123 succeeded in using fracture cement as a key diagnostic criterion for proving correspondence between the outcrop and core in a tight gas sandstone reservoir.…”

“…Insights from outcrop observations are important to complement fracture geometry interpretation, and along with density derived from subsurface data, a better understanding of natural fracture networks can be attained . The prerequisite is that the outcrop formation must have equivalent previous stress fields besides the final structural characteristics, relative timing, identical depositional environment, and diagenesis similar to the reservoir . Therefore, similarity in structural setting and lithofacies, similarity in fracture and host rock cement sequences in the same rock types, and presence of quartz in the fractures are vital for a good analog outcrop of subsurface fractures .…”

Discrete fracture modeling by integrating image logs, seismic attributes, and production data: a case study from Ilam and Sarvak Formations, Danan Oilfield, southwest of Iran

“…However, they did not generate a 3D model to display these parameters across the field. Fracture modeling in this complex structural basin reveals how faults and fractures impact reservoir properties and production rates (Zhao et al 2014;Xiaoxia et al 2021).…”

Numerical simulation of high-resolution azimuthal resistivity laterolog response in fractured reservoirs

“…It can not only increase the pore space and permeability, but also control the formation, distribution, and capacity of oil and gas in place (Jiang et al 2004;Zeng et al 2007;Zhang et al 2009;Weng et al 2011;Nie et al 2012;Kuchuk and Biryukov 2014;Reynolds et al 2014;Yao et al 2013;Zhao et al 2014). Fracture identification and quantitative characterization are keys to effective exploration of fractured reservoirs (Bourbiaux 2010;Sun et al 2011).…”