The variogram and the simple kriging estimator: Useful tools to complement lithologic correlation in a complex fluvial depositional environment
- IT Corp., Martinez, CA (United States)
Three dimensional grid estimation has been combined with an interpretive model of fluvial deposition for correlating low permeability zones in the shallow subsurface. Improvement in correlation reliability was realized by combining hand drawn interpretive cross-sections (spotting local trends in grain size, CPT log signature, etc.) with cross-section maps of the geostatistical grid model. The site is a military installation where soil contamination is being mapped and quantified using three dimensional modeling techniques. The subsurface is a complex fluvial depositional environment with intermittent bedrock highs and more frequent calcite and Calcium/Iron related cementation. Hence, the problem of lithologic correlation occurred where the drillhole spacing became wider than the channel belt width or cemented materials prevented detailed sampling. The goals of the sampling and analysis plan called for sampling within the first continuous silt or clay unit in order to quantify the zone of greatest contaminant retention on its downward migratory path. This paper will describe a three dimensional correlation technique which employs geostatistical analysis of CPT hole data specifically coded by permeability indicator thresholds. The process yielded variogram ranges applied to a simple kriging estimator on a 3-dimensional grid block. Estimates of clay probability are then provided as output and overlaid with the geologists cross section interpretation. The marriage of these two tools was invaluable in that geostatistical estimates sometimes behaved contrary to the channel depositional process, while on the other hand, the geologists interpretation often failed to recognize data in the third dimension (i.e. off section CPT data).
- OSTI ID:
- 215563
- Report Number(s):
- CONF-951139-; TRN: IM9618%%247
- Resource Relation:
- Conference: 16. hazardous waste conference and exhibition: new frontiers in hazardous waste, Washington, DC (United States), 6-8 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Superfund 16: Conference and exhibition proceedings. Volume 2; PB: 817 p.
- Country of Publication:
- United States
- Language:
- English
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