Tensleep formation fracture study compendium

This Tensleep Formation Fracture Study compendium contains the field studies, core analyses and literature reviews conducted over the 2007-2010 period in an effort to understand the characteristics and distributions of fractures and their influence on fluid flow within Tensleep Formation reservoirs. The studies reported here are the results of a large-scale project on fractures in the Tensleep Formation in Wyoming initiated by the Enhanced Oil Recovery Institute (EORI) at the University of Wyoming. The supporting data are also available through EORI and can be utilized in a variety of modeling software.

The suite of strain-accommodation structures at Flat Top and Beer Mug anticlines consists of early-formed regional compression-related extension fractures (F0) and later-formed dip-parallel (F1) and strike-parallel (F2) extension fractures, both bedding-parallel shear planes (S1), additional shears such as deformation bands with a variety of strikes (S2), and wrench fault related fractures (F3). Most of these structures formed during anticline development, as the strata were extended parallel to and oblique to the anticlinal hinge. Additional structures, some with similar orientations, formed at different times during structural development of the anticlines. As folding intensified and tightened many of these structures were reactivated with differing senses of offset, leaving a suite of compound features that do not record a simple, linear, progressive sequence of development for individual strain-accommodation structures.

Though complex, the variability in the fracture patterns can be synthesized and captured in idealized fracture models constructed with the understanding that local variations are common. Development of a thorough understanding of fracture characteristics and distributions within the Tensleep Formation over a spectrum of anticlines, with Flat Top and Beer Mug Anticlines as end members, will allow operators to place wells in the optimum positions and design enhanced oil recovery (EOR) programs to maximize efficiency.