OIP (Optical Image Profiler)
What is Geoprobe® Direct Image® OIP?
- OIP produces a detailed log of UV induced fuel fluorescence.
- A downhole camera operates at 30 frames per second (fps) to capture fuel fluorescence.
- The acquisition software analyzes each image for typical fuel fluorescence color.
- The results are the percent of the image area (up to 100%) that displays fuel fluorescence.
- Fluorescence images are saved in the log every 0.05ft (15mm) for review at a later time.
- OIP is simple to learn and operate.
- OIP log Interpretation is intuitive, made simple by the saved images to compare to the log.
- The OIP probe contains both 275nm UV and visible LEDs.
- Able to automatically and manually capture visible soil images.
- Collect OIP fluorescence and EC data with optional probe configurations that include HPT or CPT data.
The OIP (optical image profiler) is a direct push tool used to map relative distribution of LNAPL fuels and light oils with depth in soil. Figure 1 shows an example OIP log.
Figure 1: An OIP Log displaying soil EC (left) OIP Percent area fluorescence (middle) and the saved image from 14.50ft of fluorescence on the right column under the title “Captured”. The analyzed image on the far-right column show the pixels of the saved image the software has determined to display fluorescence. OIP logs can be reviewed in the DI Viewer software (link here).
OIP Principle of Operation
The OIP is a tool for mapping light non-aqueous phase liquids (LNAPL), residual LNAPL, and light oils. The OIP system utilizes a 275nm ultraviolet (UV) light emitting diode (LED) to produce fluorescence from the polycyclic aromatic hydrocarbons (PAHs) contained in fuels and light oils. The UV light is directed out a sapphire window in the side of the probe onto the soil. When LNAPL level fuels are present, the PAH molecules will absorb the UV light energy and shortly afterwards emit a light photon (fluorophore) which is the resultant fluorescence. Directly behind the sapphire window, the onboard camera (Fig. 2) captures images of the soil and any fluorescence produced by hydrocarbon contaminants present. The acquisition software analyzes each pixel of the images taken for the presence of color typical of fuel fluorescence. If there is no fuel present in the formation, or it is not in high enough concentration, then the returned camera image will appear black or dark under the UV light source. The OIP acquisition software logs percent area fluorescence with depth (Fig. 1). The OIP probe contains a visible as well as UV LEDs. The visible images are useful for determination of soil color, texture and occasionally confirming the presence of fuel or oil LNAPL globules.
Up-hole the OIP interface (Fig 1) controls the output power and lighting commands which it sends to the probe. The interface also receives the images which are passed to the computer. UV images (Fig. 3) are saved every 0.05ft (15mm). The UV images are useful for confirming the percent fluorescence values seen in the log and to evaluate the possibilities of false positive mineral fluorescence. During the logging process, as additional rods are added to the rod string, the system will automatically switch light sources from UV to visible and take still images at the current depth in both modes.
Figure 2: The OIP Probe is constructed with visible and UV LEDs which are directed out the sapphire window. Logs are typically performed with in UV mode for mapping fuel fluorescence and will switch between the visible and UV light source on rod changes. OIP acquisition software logs OIP percent area fluorescence and EC with depth.
Figure 3: UV fluorescence photo with a corresponding visible image at the same depth. Looking closely at the two photos it is possible to see the outline of the fuel in the visible image that is fluorescing in the UV image.
Figure 4: OIP Tool string diagram (TSD) shows the connection diagram of the OIP probe to the trunkline. This tool can be operated with either 1.5in (3.8cm) or 1.75in (4.4cm) rods and advanced with up to a model 7822DT direct push machine.
OIP can also be combined with HPT (Fig. 5) which allows for the collection of soil permeability measurements along with the fluorescence profile (Fig. 6) to assess contaminant mobility and transport.
Figure 5: OiHPT System components
Figure 6: Graphs left to right: Soil EC, HPT pressure (formation permeability) along with absolute piezometric pressure (secondary axis), UV percent area Fluorescence, saved UV image from 24.20ft, and estimate hydraulic conductivity (estimated K).
OIP Tool Configurations
OP6560: OIP-EC Probe
Figure 7: This OIP tool includes 275nm UV and visible light sources and EC soil measurements.
OH6570: OIP-HPT-EC Probe
Figure 8: This OIP tool includes 275nm UV and visible light sources, HPT injection pressure and EC soil measurements.
OP6610: OIP-EC-CPT Sub
Figure 9: This OIP-CPT sub includes 275nm UV and visible light sources along with EC soil measurements. This sub connects with a NOVA CPT cone for collecting CPT tip resistance, pore pressure and sleeve friction. CPT system and cone are sold separately.