Focus on Geology to Define Subsurface Migration Pathways Rick - PowerPoint PPT Presentation

Focus on Geology to Define Subsurface Migration Pathways Rick Cramer, MS, PG (Orange, CA) Mik Sh lt PhD (C Mike Shultz, PhD (Concord, CA) d CA) December 2, 2015

Outline Outline Introduction Why does geology matter? What is Environmental Sequence Stratigraphy? Proof of concept Proof of concept The technology Case Studies Page 2

Technology Established in the Oil Industry Technology Established in the Oil Industry In the early days of exploration and production, once oil reservoir was discovered, production was limited discovered production was limited by facilities capacity (engineering focus). As technology improved and fields matured, the easy stuff matured the “easy stuff” had been had been recovered. Problems such as water production became critical. Understanding the geology and Understanding the geology and predicting reservoir architecture became increasingly critical for economical operations. Page 3

Subsurface Heterogeneity and Groundwater Remediation Subsurface Heterogeneity and Groundwater Remediation • Historically, simplifying assumptions of Groundwater gradient aquifer homogeneity and isotropy applied to designing and implementing groundwater remediation programs – the “water supply legacy” • While heterogeneity was recognized, it was thought that we could “engineer around g geology” gy Contaminant plume Contaminant plume Page 4

Subsurface Heterogeneity and Groundwater Remediation Subsurface Heterogeneity and Groundwater Remediation With heterogeneous geology groundwater flow may not match gradient and result in: • Off-gradient contaminant migration • Poor distribution of in situ reagents • Production of byproducts byproducts during in situ injection • Poor pump- and and-treat treat performance Page 5

Why Geology Matters Why Geology Matters • At least 126,000 sites across the U.S. have contaminated groundwater that requires remediation • Over 12,000 of these sites are Over 12,000 of these sites are considered "complex" • “There is general agreement among practicing remediation professionals, practicing remediation professionals however, that there is a substantial population of sites, where, due to inherent geologic complexities inherent geologic complexities , restoration within the next 50-100 years is likely not achievable.” Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites National Academy of Sciences Committee on Future Options for Management in the Nation's Subsurface Remediation Effort, 2013 Page 6

Environmental Sequence Stratigraphy (ESS ) Process Environmental Sequence Stratigraphy (ESS ) Process Borehole Log to Borehole Log to Graphic Grainsize Log Graphic Grainsize Log Grain-size increasing Gravel Clay Cross Section 0 Map 100 Uncon Depth (Ft - MSL) 200 1 300 Determine depositional Determine depositional Uncon 400 environment which is the foundation to the ESS 2 evaluation Leverage existing lithology Leverage existing lithology data to identify vertical grain size trends and correlate 3 between boreholes Map the permeability architecture to predict contaminant migration Page 7

All sites currently have high resolution data… All sites currently have high resolution data… Boring Logs CPT Logs Geophysical Logs …lithology data that is not being used to its full capacity. Page 8

Environmental Sequence Stratigraphy (ESS) Environmental Sequence Stratigraphy (ESS) Beauty of this approach is that the data are already paid for and the Oil Industry has l d id f d th Oil I d t h already invested billions in developing the t technology. h l Page 9

Where is Environmental Sequence Stratigraphy applied? Where is Environmental Sequence Stratigraphy applied? ESS Clastic (sand/silt/clay mixtures) Fractured Karst sedimentary deposits? rock? limestone? • River deposits River deposits • Desert systems • Coastal settings • Marine deposits • Glacial deposits Page 10

Focus on geology improves site characterization throughout the remediation life cycle: the remediation life cycle: • Data gaps investigations, high-resolution site characterization programs • Optimizing groundwater monitoring programs • Contaminant source identification for comingled plumes • Mass flux/mass discharge analysis (contaminant transport vs contaminant storage zones) • In situ remediation (optimize distribution) In situ remediation (optimize distribution) • Optimizing pump and treat programs • Alternative endpoint analysis Alternative endpoint analysis Page 11

Proof of Concept Base-Wide Conceptual Site Models Have successfully applied this technology to assess groundwater contaminant pathways at several Air Force facilities facilities. Page 12

Proposed EPA Ground Water Issue Paper on ESS Water Issue Paper on ESS Page 13

OK, but what IS IT already? OK, but what IS IT already? ESS is “Pattern Recognition” • Patterns in grain size are the language of heterogeneity • Sequence Stratig raphers p are the translators • Can correlate/predict heterogeneity at all scales • There are grain size There are grain size patterns buried within existing boring logs of every site • Experience and d background of the practitioner is a prerequisite Page 14

0 0 r fac ~ ea tr " S ~ 0 1 ~ 1 1 ... "'"" A lluvial Fa n Pr ox imal fa n channe ls , Playa lake deposH s or Lateral ly e xt e ns iv e playa lake de pos H s can missed by tr adH i on al sampling High in ve rt ical se ns e, mid- fa n sheet sands, paleosol formati ons met ho ds due to their thin nature, bu t can ve rt ical ly compartmentali ze aquifers. m ed ium to low in d is tal fringe sands co mm only ve rt ical ly Fa ns have a prima ry s tr atigra ph ic dip basin w ard at 1 -6 degr ees , and are ho riz on tal se ns e separate fa ns . Debr is- flow laterally o ff set slac ked (' sh ingl ed ") . X: 1 02 m - 1 0' m Y : 10 1 m - ~ m de pos H s also co mm only 7 Z: 1 0" 1 m - 1 1Ys m clay-rich X: 1 0' m - 1 0' m Y: 1 0' m - 10' m Z: 1 0" 1 m - 1 1Ys m Meanderi ng Ch annel axial fill, po int Fl oo dplain de pos H s, levee Du e to w ell-sort ed sand and gravel at ba ses of channe ls , permeability can be High bo th lateral ly and Fluv ial bar, creva ee e e-p la ye- depoe- it e, clay drape e- on ordere o f magn it ude higher in t hie z on e. High r ie k of o ff e- it e c on taminant ve rt i ca l ly if e- it e e- i ze ie X :1 m - 1 1Ys m lateral acc reti on su tr a nspo rt due to groundw ater flow c on tr oll ed by channel orientati on and no t greater than channel ) Y: 1 0' m- 10' m pl ugs filli ng abandoned groundw ater gradien t. Local groundwater flow up to 270 degr ees from w id t hs Z :1 0" 1 m - 10 m channe ls regional gradien t. Ch annel-fil ls high ly asy mm e tr ic w H h cutbank characteri zed X: 1 0' m- 10' m by sharp er os i on al ed ge and po int bar characteri zed by inte rfi ngeri ng w H h Y: 1 0' m- 10' m fl oo dplain fi nes imp act i ng po tential for c on taminant ma ss storage. Lateral Z: 1 0" 1 m - 1 1Ys m acc reti on dra pes can separate po int bar de pos H s that w ould appear to be conn ect ed lateral ly . Clay pl ugs filli ng abandoned oxbow lakes co mm on . Braided Ch annel axial fill, bar Fl oo dplain de pos H s, silt groundwater flow wH h isolat ed hig h-p ermeability zones. Overall high High, bu t dependent on Fluvial forms and clay plugs filling perm ea bility and po rosity w H h amalgamat ed channel de pos H s. Local degree of amalgamati on X :1 m - 1 1Ys m abandoned channe ls groundw ater flow up to 90 degr ees from gradient, bu t typical ly w H hin 45 of channe ls determined Y: 10 m - 1 02 m X: 1 0' m - 10' m degr ees of gradient by fi nes c on tent (greater Z: 1 0" 1 m - 1's m Y : 1o· s m - 1 02 m fi nes c on tent results in Z: 1 0" 1 m - 1's m l ess channel conn ec tivity} Off sho re bar, High-frequency Laterally extensive, sand-rich deposH s. lnter bed d ed sto rm deposH s (coarser L ow in lateral sense, high o ff shore ) tr a ns gr ess iv e sand tr a ns gr ess iv e fl oo di ng grai ned } w H h fa ir-weather de pos H s l( fi ner-g ra ined} lead to high degr ees of in ve rt ical X: 1 1Ys m - 1 02 m shal es ve rt ic al he terogeneity, and low to ve ry low K v/ Kh ratio. Y: 1 0' m- 10' m X: 1 1Ys m - 1 02 m Z :1 0" 1 m - 10 m Y: 1 0' m- 10' m Z :1 0" 1 m - 10 m Near- S ho r eface (b e ac h}, or Hig h- freque ncy Lateral ly e xt e ns iv e, san d- rich ne a r-sho re unH s in upper pa rt s of sequenc es . Low in lateral se ns e, high sho re, bay he ad delta in upper tr a ns gr ess iv e fl oo ding High d egree of interbedding of coarse and fine-grained unH s in low er pa rt s. in ve rt ical 7 deltaic pa rt , shelf in low er pa rt s shal es Silt and clay beds ca pp ing sequenc es dip basinw ard, may lead to e rr oneous X: 10's m - 1 0' m X: 10's m - 1 0' m co rr elati ons at d is tanc es of hundr eds of meters to kilometers. Y: 1 02 m - Y: 1 02 m - ~ m ~ m Z: 1 0" 1 m - 10 m Z: 1 0" 1 m - 10 m Page 15

The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity • Outcrop analog of meandering fluvial deposits • At aquifer remediation site scale • Ability to explicitly map sand body architecture in 3 dimensions • Facies Models provide predictive tool for characterization based on depositional environments Page 16

The Problem of Aquifer Heterogeneity The Problem of Aquifer Heterogeneity 10 m 250 m Page 17