 The TAP (High Resolution Temperature / Acceleration / Pressure) tool was designed to acquire borehole temperature, tool acceleration and hydrostatic pressure data. It is the successor tool to the Lamont Temperature Tool (TLT).
The TAP tool may be run in either memory mode, where the tool is fastened to the bottom of the Triple Combo and data stored in the onboard memory, or it may be run in telemetry mode, where the tool is run alone and data is recorded in real-time by the third-party DAS (data acquisition system).
Fast and slow response thermistors are mounted near the bottom of the tool to detect borehole fluid temperatures at two different rates. The thinner, fast-response is able to detect small abrupt changes in temperature, the thicker, slow-response thermistor is used to estimate temperature gradient and thermal regimes more accurately. One pressure transducer is included to turn the tool on and off at specified depths when used in memory mode. Typically data acquisition is programmed to begin 100m above the seafloor.
A 3-axis accelerometer is also included to measure tool movement downhole. These data are expected to be instrumental in analyzing the effects of heave on a deployed tool string which will lead to the fine tuning of the WHC (wireline heave compensator).
When the tool is run in memory mode, the stored data are dumped to the third party DAS upon the tool's return to the rig floor.
At a meeting in January, 1999, the Scientific Measurements Panel (SCIMP) recommended "that BRG-LDEO use the TAP tool routinely for the purpose of acquiring acceleration data and testing the efficiency of the WHC under different cable length and heave conditions. The Co-Chief scientists must be informed at the pre-cruise meeting at TAMU of the potential use of this tool and additional logging time that may result from the use of the tool." Thus, the TAP tool must be run routinely in every hole. The acceleration log can aid in deconvolving heave effects post-cruise and it has proven at times to be critical data. In almost ALL cases, the 5-ft of log data that is missed can be compensated by drilling a rat hole below the target horizon. If hole depth is so tightly constrained that this is not possible, then a truly compelling reason should be provided (e.g. fault at TD, etc.).
Geothermics:
The recording of temperature provides an insight into the thermal regime of the formation surrounding the borehole. The vertical heat flow is estimated from the vertical temperature gradient combined with the measurements of the thermal conductivity from logs or core samples.
Hydrogeology:
Crust at mid-ocean ridge crests must be permeable to a considerable depth to allow for the efficient removal of heat by hydrothermal systems. Temperature logs in such an environment can clearly differentiate between the advective (hydrothermal) and conductive heat transfer regimes.
Drilling and circulation operations considerably disturb the temperature distribution inside the borehole thus preventing equilibrated temperature conditions. The amount of time elapsed between the end of drilling fluid circulation and the beginning of logging operations is not long enough to allow the borehole to recover thermally. Therefore the data recorded is not representative of the thermal equilibrium of that environment. In addition, the thermistors may become fouled with sediment from the drilled formation which reduces the sensitivity and accuracy of the recorded temperature data.
Temperature data acquired by the fast and slow thermistors may be presented with resistivity, density and porosity log data. Temperature data may also be imported into GeoFrame for inclusion in plots made during the leg.
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Tool Length:
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8.895 ft (2.71 m) |
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Tool Diameter:
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3.25 in (8.26 cm) |
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Temperature Rating:
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105° C / 220° F |
| Acceleration Measurement Range: |
-2g to +2g |
| Acceleration Resolution: |
1 mm/s2 |
| Acceleration Sampling Rate: |
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Low Resolution Mode (LR): |
4 Hz |
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High Resolution Mode (HR): |
8 Hz |
| Temperature Measurement Range: |
-4°C to +85°C |
| Temperature Resolution: |
0.005 °C |
| Pressure Measurement Range: |
0 to 10,000 psi |
| Pressure Resolution: |
1 psi |
| Pressure Measurement Precision: |
0.1% FS |
| Temperature / Pressure Sampling Rate: |
1 Hz |
| Total Data Recording Time: |
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HR mode |
5 hrs. |
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LR mode |
8 hrs. |
| Power Source: |
8 alkaline batteries (D type) |
| Operation Time From One Set of Batteries: |
approx. 40 hrs. |
The TAP tool can be deployed in two modes, memory mode and telemetry mode. In memory mode, the TAP is deployed in the same fashion as the superseded TLT. This requires the logger to initialize the tool approximately 1/2 hour prior to rig up of the lower most Triple Combo tool, typically the DIT. Once initialized, the TAP tool should be placed on the deck outside of the DHML to be picked up by the roughnecks. The logger then must connect it to the bottom of the triple combo using a pin and rotating ring assembly. When the Triple Combo is retrieved to the rig floor, the Lamont logger must remove the TAP tool, wash it off and download the data.
When the telemetry cartridge is completed in mid FY 00, the TAP tool may be run in telemetry mode which precludes from running it with the triple combo. In telemetry mode, the TAP tool will be deployed in a similar fashion as a Schlumberger tool. The tool will be placed outside the DHML door for rigging by the rig floor crew. A tugger will hoist the tool for insertion into pipe where it will be held by the Schlumberger make-up plate. From here, the Schlumberger cable head will be fastened to the TAP tool with a standard Schlumberger field joint. The Logging Staff Scientist will then be responsible for conducting the entire logging operation for this tool. This includes coordination with the winch shack, rig floor and Schlumberger engineer. Detailed instructions for the telemetry mode deployment will be available following prototype field testing.
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