Methods and systems for stimulating and detecting the biological degradation of hydrocarbons and biogeochemical cycles in contaminated soils
This document discusses depletion sensors and soil monitoring systems, including soil bioremediation systems and methods. A depletion sensor may have a sensor tubing; and a plurality of sensor modules on or within the sensor tubing and longitudinally spaced in series along the sensor tubing at different respective longitudinal positions, which correspond to different respective depths of each sensor module when the depletion sensor is in use inserted within underground soil below a ground surface, each sensor module having: a housing; a sensing part within the housing; and a port in the housing putting the sensing part in fluid communication with an exterior of the sensor tubing at the respective longitudinal position of the sensor module along the sensor tubing. Underground soil monitoring systems may include a network of depletion sensor wells penetrating the ground surface, with each of the depletion sensor wells containing a depletion sensor. Long term in situ biogeochemical carbon monitoring of underground soil may be carried out at a site.
1. A method of long term in situ biogeochemical carbon monitoring of underground soil at a site, the method comprising:
monitoring, over an extended period, levels of carbon-containing compounds in the underground soil, using plural depletion sensor wells that are arranged within the underground soil below a ground surface at the site and that remain in the underground soil over the extended period, each of the plural depletion sensor wells having a plurality of sensor modules located at two or more isolated depth zones along the depletion sensor well, with the two or more isolated depth zones being separated by bore wall sealing parts between the plurality of sensor modules;
in which monitoring further comprises using a controller connected to the plural depletion sensor wells, the controller configured to one or more of:
collect data continuously or at intervals;
store the data locally; and
transmit the data;
in which the underground soil is hydrocarbon contaminated soil;
in which monitoring comprises monitoring a microbial degradation process by using the plural depletion sensor wells to measure individual levels of each of the following: carbon dioxide, methane, hydrocarbons, and nitrous oxide, in the underground soil; and
in which monitoring further comprises using a processor to analyze data, from the plural depletion sensor wells and including depth positions of each of the plurality of sensor modules, to determine natural source zone depletion (NSZD) rates of hydrocarbons in the underground soil at the site.
2. The method of claim 1 in which the plurality of sensor modules take continuous or periodic readings over the extended period.
3. The method of claim 1 in which the extended period is a month or longer.
4. The method of claim 3 in which the extended period is a year or longer.
5. The method of claim 1 in which:
each of the plural depletion sensor wells contains a sensor tubing;
the plurality of sensor modules each comprise a plurality of sensors, and are on or within the sensor tubing and longitudinally spaced in series along the sensor tubing at different respective longitudinal positions, which correspond to different respective depths of each sensor module below the ground surface.
6. The method of claim 5 in which each sensor module has
a housing;
a sensing part within the housing; and
a port in the housing putting the sensing part in fluid communication with an exterior of the sensor tubing at the respective longitudinal position of the sensor module.
7. The method of claim 1 in which the plural depletion sensor wells includes:
depletion sensor wells that are inserted into the hydrocarbon contaminated soil; and
depletion sensor wells that are inserted into underground soil adjacent to the hydrocarbon contaminated soil.
8. The method of claim 1 further comprising injecting liquid chemicals in situ through a plurality of injection wells into the hydrocarbon contaminated soil, in which the liquid chemicals are selected to biostimulate a microbial degradation process of hydrocarbons to remediate the site.
9. The method of claim 8 in which injecting further comprises controlling the injection of liquid chemicals in situ through the plurality of injection wells in response to signals from the plurality of sensor modules.
10. The method of claim 1 further comprising drilling the plural depletion sensor wells and inserting the plurality of sensor modules therein.
11. The method of claim 1 in which the plural depletion sensor wells are arranged in a network of depletion sensor wells that are arranged at different locations at the site.
12. The method of claim 1 further comprising delivering gas through a tube into one or more of the plural depletion sensor wells.
13. The method of claim 1 in which the bore wall sealing parts each comprise a gasket on exterior surfaces of the plural depletion sensor wells.
14. The method of claim 1 in which the bore wall sealing parts comprise a fluid impermeable barrier or pack between each of the two or more isolated depth zones.
15. The method of claim 14 in which the fluid impermeable barrier or pack comprises bentonite.