3-D Reservoir and Stochastic Fracture Network Modeling for Enhanced Oil Recovery, Circle Ridge Phosphoria/Tensleep Reservoir, Wind River Reservation, Arapaho and Shoshone Tribes, Wyoming

Abstract

This report describes the results made in fulfillment of contract DE-FG26-00BC15190, "3-D Reservoir and Stochastic Fracture Network Modeling for Enhanced Oil Recovery, Circle Ridge Phosphoria/Tensleep Reservoir, Wind River Reservation, Arapaho and Shoshone Tribes, Wyoming". The goal of this project is to improve the recovery of oil from the Tensleep and Phosphoria Formations in Circle Ridge Oilfield, located on the Wind River Reservation in Wyoming, through an innovative integration of matrix characterization, structural reconstruction, and the characterization of the fracturing in the reservoir through the use of discrete fracture network models.Fields in which natural fractures dominate reservoir permeability, such as the Circle Ridge Field, often experience sub-optimal recovery when recovery processes are designed and implemented that do not take advantage of the fracture systems. For example, a conventional waterflood in a main structural block of the Field was implemented and later suspended due to unattractive results. It is estimated that somewhere less than 20% of the OOIP in the Circle Ridge Field have been recovered after more than 50 years' production.Marathon Oil Company identified the Circle Ridge Field as an attractive candidate for several advanced IOR processes that explicitly take advantage of the natural fracture system.These processes require knowledge of the distribution of matrix porosity, permeability and oil saturations; and understanding of where fracturing is likely to be welldeveloped or poorly developed; how the fracturing may compartmentalize the reservoir; and how smaller, relatively untested subthrust fault blocks may be connected to the main overthrust block.For this reason, the project focused on improving knowledge of the matrix properties, the fault block architecture and to develop a model that could be used to predict fracture intensity, orientation and fluid flow/connectivity properties.Knowledge of matrix properties was greatly extended by calibrating wireline logs from 113 wells with incomplete or older-vintage logging suites to wells with a full suite of modern logs. The model for the fault block architecture was derived by 3D palinspastic reconstruction. This involved field work to construct three new cross-sections at key areas in the Field; creation of horizon and fault surface maps from well penetrations and tops; and numerical modeling to derive the geometry, chronology, fault movement and folding history of the Field through a 3D restoration of the reservoir units to their original undeformed state. The methodology for predicting fracture intensity and orientation variations throughout the Field was accomplished by gathering outcrop and subsurface image log fracture data, and comparing it to the strain field produced by the various folding and faulting events determined through the 3D palinspastic reconstruction. It was found that the strains produced during the initial folding of the Tensleep and Phosphoria Formations corresponded well without both the orien...

Developing a model discrete fracture network, drilling, and enhanced oil recovery strategy in an unconventional naturally fractured reservoir using integrated field, image log, and three-dimensional seismic data

“…Gilbertson (2006) estimated fracture aspect ratio for the Tensleep Sandstone using a value for mean fracture length of 50 m (164 ft) reported by LaPointe et al (2002). Gilbertson (2006) reported a geometric mean fracture height of 17.53 m (57.5 ft) and used the mean length reported by LaPointe et al (2002) to obtain an aspect ratio of 0.35. In this study, we estimate aspect ratio using mean height (3.04 m [10 ft]) and mean length (9.1 m [30 ft]) to obtain an aspect ratio of 0.33.…”

Fracture Characterisation Using 3-D Seismic Reflection Data for Advanced Deep Geothermal Exploration in the Ne German Basin

“…However, fault zones and fracture networks often bear an inherent small-scale complexity close to the seismic resolution, so that it is difficult to resolve them directly from the data. For this purpose, various options for attribute analyses e.g., coherence, curvature, RMS amplitude and instantaneous frequencies, ant-tracking analysis, spectral decomposition using wavelet transform, impedance inversion and crossplots (Gazar et al, 2011;Suo et al, 2012;Pussak et al, 2014;Marfurt, 2018;Ziesch et al, 2019;Bauer et al, 2020;Wadas and von Hartmann, 2022;Wadas et al, 2023) and numerical modelling, such as 3-D palinspastic reconstruction (LaPointe et al, 2002), exist to better explore the sub-seismic scale of fracture networks (Krawczyk et al, 2015).…”