Effect of mechanical and physical properties of rocks on post-failure cavity development - Experimental and numerical studies

B. Wu, S. K. Choi

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

3 Citations (Scopus)

Abstract

This paper presents a combined laboratory experimental and numerical modeling study on fundamental mechanisms of sand production-induced post-failure cavity development. The laboratory component of the study utilized a sand production apparatus that accommodates a cylindrical sample with a pre-drilled central hole. The experiments were conducted by producing a fluid from the central hole of the pre-stressed sample. The failure condition of the central hole was monitored using a borescope. Experimental results demonstrated that sanding behavior and post-failure cavity development were vastly different for different types of rocks tested. At a constant external stress and drawdown pressure, transient sand production was observed for competent sandstones where a breakout type cavity was developed. By contrast, continuous sand production was observed for weak and porous sandstones where a thin-slot type cavity was formed. Little sand production was observed for low permeability ductile sandstone where classic shear band type of failure was developed. For compacted unconsolidated sands, continuous sand production was observed where no open cavity was developed. To understand the factors responsible for such distinctly different sanding behavior and cavity development, the laboratory experiments were simulated preliminarily using a hybrid discrete element-finite element (DE-FE) model. The numerical results showed that the properties and characteristics of the cementation between sand grains have a determining role in the post-failure cavity development. In particular, the cement strength, distribution, degree of brittleness, the degree of cementation and the properties of the pore fluid affect what type of cavities that will be formed and how sand production will evolve.

Original languageEnglish
Title of host publication46th US Rock Mechanics / Geomechanics Symposium 2012
PublisherAmerican Rock Mechanics Association (ARMA)
Pages1015-1024
Number of pages10
Volume2
ISBN (Print)9781622765140
Publication statusPublished - 2012
Externally publishedYes
EventUS Rock Mechanics / Geomechanics Symposium 2012 - Chicago, United States of America
Duration: 24 Jun 201227 Jun 2012
Conference number: 46th

Conference

ConferenceUS Rock Mechanics / Geomechanics Symposium 2012
CountryUnited States of America
CityChicago
Period24/06/1227/06/12
OtherThe American Rock Mechanics Association invites you to its 46th Mechanics/ GeoMechanics Symposium to be held in Chicago, Illinois, USA on 24-27 june 2012

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