Title: Quantifying opening-mode fracture spatial organization in horizontal wellbore image logs, core and outcrop: Application to Upper Cretaceous Frontier Formation tight gas sandstones, USA

Abstract

The Upper Cretaceous Frontier Formation is a naturally fractured gas-producing sandstone in Wyoming. Regionally, random and statistically more clustered than random patterns exist in the same upper to lower shoreface depositional facies. East-west- and north-south-striking regional fractures sampled using image logs and cores from three horizontal wells exhibit clustered patterns, whereas data collected from east-west-striking fractures in outcrop have patterns that are indistinguishable from random. Image log data analyzed with the correlation count method shows clusters ~35 m wide and spaced ~50 to 90 m apart as well as clusters up to 12 m wide with periodic inter-cluster spacings. A hierarchy of cluster sizes exists; organization within clusters is likely fractal. These rocks have markedly different structural and burial histories, so regional differences in degree of clustering are unsurprising. Clustered patterns correspond to fractures having core quartz deposition contemporaneous with fracture opening, circumstances that some models suggest might affect spacing patterns by interfering with fracture growth. Our results show that quantifying and identifying patterns as statistically more or less clustered than random delineates differences in fracture patterns that are not otherwise apparent but that may influence gas and water production, and therefore may be economically important.

Authors:

Li, J. Z.; Laubach, S. E. ;

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Gale, J. F. W.; Marrett, R. A.

Publication Date:

Sat Jul 01 00:00:00 EDT 2017

Research Org.:

Univ. of Texas, Austin, TX (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1369079

Alternate Identifier(s):

OSTI ID: 1509838

Grant/Contract Number:  

FG02-03ER15430

Resource Type:

Published Article

Journal Name:

Journal of Structural Geology

Additional Journal Information:

Journal Name: Journal of Structural Geology; Journal ID: ISSN 0191-8141

Country of Publication:

United Kingdom

Language:

English

Subject:

58 GEOSCIENCES; cluster; corridor; fractal; spacing; swarm; unconventional reservoir