1.0 Purpose/Scope

1.1 Overview

Introduction           

This manual describes the third generation of IODP temperature hardware and software to be used to determine sub seafloor temperatures within sediments during piston coring operations.

The APCT-3 tool is a data logger that captures time-dependent temperature data in a deep-sea borehole.

For additional information on interpreting the data, log in to Cumulus and download the User Manual for the Third-Generation, Advanced Piston Corer Temperature Tool (APCT-3) by Fisher, Villinger, and Heeseman (Cumulus web version at http:// web.iodp.tamu.edu:8080/CumulusE/ng/index.jspx or Cumulus Client on your computer).

2.0 Introduction

2.1 Overview

Introduction   

The APCT-3 tool is deployed on the APC inner core barrel, which is run on the coring wireline to the bottom of the borehole. The APCT-3 temperature logger electronics are mounted inside the annular cavity of a Heat Flow Coring Shoe (OP4375).

The combined APCT-3 tool and coring shoe is attached to the APC tool during coring operations to obtain borehole temperature at the same time a hydraulic piston core is retrieved, eliminating the costly delay of entering the borehole twice with two separate investigation tools. APCT-3 data are downloaded from the data logger onto a computer on the ship.

In situ temperature measurement adds ~10 min to each APC core barrel run. Mudline measurements can add 5 min more.

2.2 APCT-3 Operational Overview

Deployment            

The tool is deployed in soft sediments to determine:

• Formation temperature
• Heat flow gradient
• Hydrocarbon maturity

Typically, the tool is run starting at 30 meters below seafloor (mbsf) and then run with every other core until four good readings are obtained. The shoe is hydraulically stroked 9.5 m into the sediment and remains stationary for ~10 min.

The APC Inner Core Barrel is then retrieved, the instrumented shoe is removed, and data are downloaded to a computer.

APC pullout and partial penetration

The crew normally switches to extended core barrel (XCB) coring after an APC pullout of 60,000–100,000 lb (this decision is left to the rig crew, Tool Pusher, and IODP Operations Superintendent). Leaving the APC barrel in the mud for the extra minutes required by APCT operation allows the formation to settle in around the tool and may increase the pull required to remove the tool from the mud. In the past during some APCT runs, when the sediment firmed up at shallow depths, researchers agreed to pull out after 6–8 min. If the tool is left in the sediment for any time period less than this, it may be difficult to get enough of an equilibration curve to

extrapolate a meaningful in situ temperature (see Fisher et al.), but much depends on drilling conditions, water depth, sea state, lithology, and other factors. You can experiment with the length of measurement with the TP- Fit software (see APCT-3 Data Processing (TP-FIT) on page 4-13).

During later ODP and early IODP operations, drilling crews continued to core using the APC to great depths (300 m or more) using a “drillover” technique. The APC drill bit was advanced the length of recovery following incomplete stroke, and another APC barrel was launched. This approach requires more time, since the depth increment of each core might be only a few meters, but it allows collection of high-quality APC samples, and APCT-3 data, to much greater depths than have been attained previously. Discuss this option early in the expedition (or during pre-expedition planning) if deep APC (and APCT-3) penetration is important to the scientific objectives.

Data storage         

Temperature data are time stamped and stored in external erasable programmable read-only memory (EEPROM) within the tool.

Temperature range

The APCT-3 tool has a temperature range -5°C to +50°C with an accuracy of +/-0.02°C (see Chapter 6, Specifications) and a resolution of <2.5 mK at

–5° to +50°C range and <1.0 mK at <25°C.

Dual deployment option

As part of the APCT-3 development, an option was created to deploy two sets of APCT-3 electronics, with a sensor-to-sensor spacing of ~57.2 cm (22.5 in) during a single Advanced Piston Corer (APC) deployment (see Dual deployment (OM0700) on page 6-9 or Fisher et al., 2007 in Cumulus [full citation is listed in the Bibliography on page 6-13]), but IODP has not operated the tool in this configuration as of 2010.

2.3 APCT-3 Components

Overview               

The tool system comprises three main components:

• Coring hardware
• Electronics components
• Operating software

Coring hardware

Primary coring hardware components (Fig. 2-1) of the APCT-3 tool include:

• Heat Flow Shoe with annular cavity (OP4375)
• Heat Flow Catcher Sub Body (OP4377)

Figure 2-1.  APCT-3 Components.

Heat Flow Shoe (OP4375)

APCT-3 electronics are deployed inside a coring shoe. The APCT-3 shoe differs from the shoe used with second-generation tools only in the depth extent of the O-ring surfaces (they are slightly longer) and in labeling instructions for the vendor. The coring shoe tapers near the cutting end, placing the APCT-3 thermistor probe within ~1-2 mm of the outer surface of the shoe. In addition, the taper of the cutting shoe helps to assure that it makes good thermal contact with the surrounding formation.

Heat Flow Catcher Sub

The Heat Flow Catcher Sub is cylindrical in cross-section and forms the seal at the top of the annular cavity. The top of the sub screws onto the bottom of the Inner Core Barrel.

Electronics            APCT-3 tool electronic components (Fig. 2-2,Fig. 6-1, p. 6-3) have an operating temperature range of approximately –5° to +55°C (except the batteries which have a maximum temperature range of +70°C (see Measurement temperature range on page 6-4) and include:

• Electronics Support Frame(OM0720)

—    Battery Circuit Board

—    Temperature Logger Circuit Board

—    O-Rings

—    Prongs

—    Locating pins and screw holes

—    Banana Plugs

• Top Ring (OM0705)
• Frame Insertion-Extraction tool (OM0830)
• Communication Cable (OM0722) (not shown in Fig. 2-2; see Fig. 2-6, p. 2-10)

Electronics Support Frame

The Electronics Support Frame (Fig. 2-2, p. 2-6) houses two circuit boards, which are built into the aluminum cylindrical support frame. Three flat surfaces are machined onto the older generation support frames and four on the new APCT-3 frames. On both frames, two of the flat surfaces are currently used to hold circuit boards, and one (APCT)/two (APCT-3) remain empty for potential future use.

Battery Circuit Board

One circuit board (Fig. 2-2, p. 2-6) holds two 1.3 V lithium coin cells (manufacturer’s part number is CR2430-P2-2) in parallel, providing a 3 V power supply to the tool. One set of batteries should allow for ~600,000 readings; at a sampling rate of one per second, the tool should operate ~1 week on a set of batteries.

Temperature Logger Circuit Board

The other circuit board (Fig. 2-2, p. 2-6) holds electronics for the following:

• Thermistor probe (YSI 55032)

—    Temperature coefficient = ~4% per °C

—    Temperature range = –80°C to +100°C

—    Temperature maximum = 200°C (thermistors tend to drift greatly when subjected to temperatures above 100°C; thermistors would probably require calibration and may be damaged)

• Microprocessor
• Analog-to-digital (A/D) converter, 16-bit
  • Memory, nonvolatile (can hold 65,000 readings)
  • Real-time clock

Electronics Support Frame, cont.

Figure 2-2.  Electronics Support Frame.

1.5 V Lithium Batteries (2)

Temperature Logger Circuit Boards (1 and 2)

1

2

Support Frame

Machined flat surface for additional circuit board

Electronics Support Frame O-Rings

The Electronics Support Frame has one O-ring located near the top and one near the base (Fig. 2-2). The O-rings stabilize the electronics only, they do not seal out moisture. The part number for the O-rings is OD2041.

Prongs

On the bottom of the support frame are two prongs F( ig. 2-2): one is empty and the other contains the thermistor probe (nominal 30 kW at 25°C).

Currently, the empty prong acts as a locating pin. A second thermistor or other sensor could be placed in the empty prong in the future as a tool modification.

Locating Pins and Screw Holes

On the top of the electronics support frame (Fig. 2-3, p. 2-7) are four threaded screw holes and four locating pin holes for use with the frame insertion-extraction tool.

Electronics Support Frame, cont.

Banana Plug Contacts

Two female mini-banana plug contacts (readout ports) are also located on the top of the Electronics Support Frame and provide access for the Communications Cable to communicate with the deck box and computer (Fig. 2-3).

Figure 2-3.  Top of Electronics Support Frame and Bottom of Frame Insertion- Extraction Tool.

Electronics Support Frame                                                 Frame Insertion-Extraction Tool

Top Ring                A Top Ring (machined steel with inner [OD2039] and outer [OD2041] O- rings) fits above the Electronics Support Frame after it is inserted in the coring shoe. The Top Ring (Fig. 2-4, p. 2-8) protects the electrical contacts from water, grease, and mud, which are otherwise exposed on the top surface of the support frame.

Top Ring, cont.      Figure 2-4.  APCT-3 Top Ring.

Frame Insertion- Extraction tool

The Frame Insertion-Extraction tool (OM0830) (Fig. 2-5, p. 2-9) was designed and manufactured by Antares. It is used when:

• Placing or removing the Electronics Support Frame into and out of the Heat Flow Shoe
• Inserting and removing the Top Ring

Ideally, an Electronics Support Frame might be placed in a Heat Flow Coring Shoe near the start of an expedition and not be removed until the end of the expedition, minimizing opportunities for damaging the electronics.

The Top Ring must be removed after every temperature run to download data.

Frame Insertion- Extraction tool, cont.

Figure 2-5.  Frame Insertion-Extraction Tool.

Frame Insertion-Extraction Tool

Electronics Support Frame and Temperature Logger Circuit Boards

Heat Flow Shoe

Communication cable

Communication is accomplished using serial communication, either through a DB-9 serial port on the computer or a USB port and a serial adapter. The Communication Cable (OM0722) attaches to a deck box, from which a second cable connects to the APCT-3 electronics.

A special connector at the end of this cable (Fig. 2-6), with male mini- banana plugs attached to a curved form, is shaped to slide into the top of the annular cavity and fit into the Electronics Support Frame to download data while the frame is in the APC coring shoe. This allows the APCT-3 electronics to be programmed and deployed, and data to be recovered, without removing the electronics frame from the APC coring shoe.

Figure 2-6.  Electrical Connector (white arrow) and Support Frame (right) .

Operating systems

The electronics are programmed using a desktop or notebook computer running Windows XP. At the time of this writing (2009), no tests had been run using Vista. Limited testing has been performed using Windows 98, but vendor specifications do not include support for this operating system.

3.0   APCT-3 Tool Assembly

3.1        Overview

Introduction            The APCT-3 Electronics Support Frame is stored in a plastic cylinder when not in use to prevent damage to the electronics.

The physical assembly of the APCT-3 has been simplified from that of the APCT tool. The batteries are built into the Electronics Support Frame and do not need changed as often.

In this chapter       This chapter contains the following topics:

3.2        Attach Frame Insertion-Extraction Tool

Introduction            Attach the Frame Insertion-Extraction tool to the APCT-3 to load it into the APCT Coring Shoe. Once the APCT-3 tool is assembled, the electronics support frame should not need to be removed from the coring shoe during the remainder of the expedition.

Parts required       •  Electronics Support Frame in storage cylinder

• APC Coring Shoe
• Frame Insertion-Extraction tool
• Stand to hold Coring Shoe and Electronics Support Frame storage cylinder

Procedure: attach Frame Insertion- Extraction tool

To attach the Frame Insertion-Extraction tool to the Support Frame, perform these steps:

3.2      Attach Frame Insertion-Extraction Tool

Procedure: attach Frame Insertion- Extraction tool, cont.

3.3        Clean, Grease, and Install the Support Frame

Overview                Before the electronics support frame is installed in the APC coring shoe, clean and grease the O-ring grooves and coat the thermistor probe with heat sink compound to ensure good contact with the coring shoe. Although the heat sink compound will not damage the electronics, try to keep it only on the probe because it makes the tool, and possibly the user, messy.

To inspect or clean the electronics, the user may extract the frame from the plastic case by pushing your hand inside the frame and lifting the Electronics Support Frame up To insert the frame into the APC shoe, use the Frame Insertion-Extraction tool.

Parts required       •  Electronics Support Frame

• Old APCT Stand or other stand to support the shoe
• Frame Insertion-Extraction tool
• Dow 4 silicone grease
• Nonsilicone heat transfer compound (PN 52050-1J0)
• Top Ring
• O-Rings (OD2041)
• Small applicator (e.g., a cotton tipped applicator)

Clean and grease Electronics Support Frame

To clean and grease the Electronics Support Frame, perform these steps:

3.3  Clean, Grease, and Install the Support Frame,

Continued

Clean and grease Electronics Support Frame

To clean and grease the Electronics Support Frame, perform these steps:

3.3  Clean, Grease, and Install the Support Frame,

Continued

Install the Electronics Support Frame

Install the Electronics Support Frame into the APC coring shoe as follows:

IODP APCT-3 Operations Manual

3.4   APCT-3 Tool Data Sheet

APCT-3

Downhole Tool Data Sheet

Sample

Time                        

sec.

Instrument #               

Core #                        

Exp                             

Site                               

Hole                            

Depth                          mbsf                                      Water Depth

(PDR)                          

Date                              

Observer                      

Water Depth

(DPM)                          

Battery Voltage Start                          

Battery Voltage Stop                           

Time (GMT)

hour              min                sec.

                   Start

Remarks:

Start down:

pumping @                       Strokes/min

Pumps off

@ Mudline                   

Stay:                    minutes

Penetration Time

Stay:                 

minutes

Pullout at                       k lbs

Extrapolated Equilibrium

Temperature =                                    °C

Uploaded to LIMS:

Output file names & locations:

Version date: May 26, 2011

3-7

3.5   Tool Programming

Introduction            If you are not familiar with operation of the APCT-3 tool, take time in port or during transit to review these instructions and run bench tests.

Operating system

The data logger is programmed using a desktop or notebook computer running Windows XP. No tests have been run usingWindows Vista; limited testing has been performed using Windows 98, but vendor specifications do not include support for this operating system.

Procedure: activate logger and check battery

To activate the tool and check the battery for the APCT-3 tool, follow these steps:

Procedure: activate logger and check battery, cont.

Figure: logger online window

Figure: logging data summary

Figure 3-1.  Logger > Online Logger Window.

Figure 3-2.  Real-Time Logging Summary of Online Data.

Procedure: activate logger and check battery, cont.

Clear logger data

After activating the tool and checking the battery, select Logger > Clear data to collect new data. There are four possible responses:

• Logger has not been run and no data are present in the window but the program requests user to clear the logger memory. Clck Yes or No.

• Logger has been run, acquisition was stopped, and the program asks if you want to clear the data in the window. Click Yes or No.

• Logger was deactivated and memory cleared. Click OK.

• Logger contains data, program requests user to clear memory before proceeding. Click OK to clear data.

Procedure: data logger setup

To prepare the data logger for a new deployment, perform these steps:

Figure: logger setup screen

Figure: logger setup verification

Figure 3-3.  Logger Setup Screen.

Figure 3-4.  Logger Setup Verification.

4.0   Tool Deployment

4.1        Overview

Introduction            The APCT-3 tools have been carefully calibrated on shore at the Metrology Lab, but it is good practice to verify bottom water temperature at each site at least once for each APCT-3 tool used during an expedition. More frequent bottom water measurements may be desirable, particularly when working in shallow water or in other environments where bottom water temperature variations are expected.

See APC pullout and partial penetration on page 2-2 for additional information on deployment.

In this chapter

4.2        Final Tool Assembly for Deployment

Procedure: final tool assembly

Finish assembling the tool, coring shoe, and core catcher sub before deploying the tool:

4.3        Running a Temperature Station

Introduction            The drill pipe is an efficient heat exchanger, so water in the pipe is generally close to bottom water temperature by the time the water reaches the bottom of the pipe, provided the water is sufficiently deep and the surface water is not anomalously warm. However, depending on the pumping rate and the ambient hydrography, water in the pipe may not equilibrate with bottom water if the pumps are running quickly. In addition, the complete APCT-3 system is thermally massive, and the best bottom water temperature measurement will be made by holding the tool stationary, a few meters above mudline, for 10-15 min with thepumps off.

When positioning the tool at the mudline, be sure to take into account the length of the core barrel. If the tool is inadvertently held below the mudline, a spurious bottom water temperature will be determined.

Procedure: running a temperature station

To run a temperature station with the APCT-3 tool, perform these steps:

e

o

4.3      Running a Temperature Station, cont.

Procedure: running a temperature station, cont.

4.4        Removing the Core

Introduction            After the core is retrieved, the APCT-3 tool must be cleaned, data downloaded, tool reprogrammed for the next run, and tool redeployed.

Special wrench      When the APCT-3 tool comes back on deck the rig crew breaks the coring shoe and core catcher sub connection with a special wrench. Stand and watch every time the rig crew breaks the connection. Failure to use the special wrench to break the connection between the coring shoe and the core catcher sub could result in a deformed coring shoe or damaged electronic components inside the shoe.

Procedure: retrieving the tool and core

To retrieve the APCT-3 tool, perform these steps:

4.4      Removing Core, Continued

Procedure: removing stiff sediment

To safely remove stiff sediment, follow these steps: .

4.5        Cleaning the Tool

Introduction            After the core is retrieved, clean the tool before downloading data to the PC.

Procedure: cleaning the tool

Clean off the tool and download the data by following these steps:

4.6        Downloading Data

Introduction            Download the data to the PC before redressing and redeploying the APCT-3. For more information on modeling see Fisher et al., 2007(see Bibliography on page 6-13 or find document in Cumulus).

Procedure: data download

To download the APCT-3 data, perform these steps:

4.6  Downloading Data, Continued

Procedure: data download, cont.

Figure 4-1.  Logger is Active Window.

4.6  Download Data, Continued

Procedure: data download, cont.

Figure 4-2.  Data File.

4.6      Download Data, Continued

Procedure: data download, cont.

Figure 4-3.  Save Data as *.wtf File.

Figure 4-4.  Export data as *.dat File.

4.7        TPFIT Quick Start

Introduction            TPFIT software is designed to work with APCT-3, SET, and SETP tool data. TPFIT is a Matlab™ program created for processing APCT-3 data.

This Quick Start guide will provide the novice user steps to do simple data processing. Section 4.8 APCT-3 Data Processing (TP-FIT) on page 4-13 provides more detailed information on using TP-FIT.

Additional resources

For advanced users, see the Formation Temperature Analysis User Guide

(Heesemann, 2007).

Definitions             The following symbols are defined as:

• k = sediment thermal conductivity
• pc = heat capacity

Procedure: process data

To process data, perform these steps:

4.8        APCT-3 Data Processing (TP-FIT)

Overview                This section provides an overview of using the TP-FIT software. TP-FIT is a MatLab program created for processing APCT-3, SET, and SETP data.

Launching             To launch TP-FIT (tpfit3.exe), perform these steps.

Figure 4-5.      TP-Fit Opening Screen before and after loading a data file.

Load Data              The Load Data button imports a data file for processing (e.g., the APCT-3 file 1329C09H.dat from the test data directory). Once a data file is loaded, the Pick, Compute contours, Load Data, and Edit Metadata buttons turn green (Fig. 4-5, p. 4-14).

Edit Metadata        When a data file is loaded, TP-Fit creates basic metadata. Select the Edit Metadata button to open the Edit Metadata screen (Fig. 4-10, p. 4-20).

The information displayed on the Edit Metadata screen becomes the header information for the data record. Initial values are filled in from the data file. Fill in any fields on this screen that are missing information.

Edit Metadata, cont.

File metadata includes the following:

• Expedition, Site, Hole, Core, and Core Type
• Depth (m)
• Tool ID (tool serial number)
• Tool Type (APCT, APCT-3, DVTP, SET)
• Operator
• Initial k (see Initial_k and Initial rC Fields (Heat Mass) on page 4-16)
• Initial rc (see Initial_k and Initial rC Fields (Heat Mass) on page 4-16)
• Comments

Figure 4-6.  Edit Meta Data Screen

Enter and review the information on the Edit Metadata screen and then click OK to close the Edit Metadata window.

Edit Metadata, cont.

Initial_k and Initial rC Fields (Heat Mass)

Initial k and Initial rc values are supplied by the program and are standard physical property values used in calculations. Do not change these values unless you know the values for the area. Part of data processing is evaluating the uncertainty in final temperatures caused by the uncertainty in k and rc values, but it is best to enter a reasonable initial value.

In the last generation of APCT processing software, the user was asked to enter only a value for k, and thermal diffusivity (K = k/rc) was calculated from the empirical relation of Von Herzen and Maxwell [1959]:

K = 3.657 x (k – 0.70)/10–7

where

k is in W/(m·k) and

K is in m2/s.

Other studies have explored relations between k and K, and the advanced user is advised to choose a favored relation initially but to explore the significance of this relation as part of APCT-3 processing (see section Computer Contours and Explore in Heeseman, 2007, available in Cumulus [use TP-FIT in the quick search]).

Pick                       The next step in processing TP-Fit data is to select the data segments to process. Three data points must be selected:

1. Tool penetration time (t0)
2. Data start (initial data point to fit to the model)
3. Data stop (final data point to fit to the model)

Click the Pick button on the opening screen to open a plot of the data record (Fig. 4-7, p. 4-17). As the data are shown in a standard Matlab plotting window, you can zoom in and out and adjust axes. TP-Fit defaults to a data processing window of 9 min (from 60 s to 600 s after penetration; see boxed area in Fig. 4-7, p. 4-17 and expanded area in Fig. 4-8, p. 4- 17). These times can be adjusted by choosing the appropriatePick button in the upper right hand side of the screen (t0, Data Start, and Data End; see Fig. 4-7, p. 4-17).

Figure: initial data plot screen

Figure 4-7.  Initial Data Plot Screen.

Zoom in on the plot (Fig. 4-9, p. 4-18) to define the data interval to process. Include data points before penetration and after penetration, including several minutes of data prior to tool penetration.

Figure 4-8.  Data Plot with t0 (dark vertical dotted line) and Data Start Pick (crosshair cursor).

Select Data Start

Select the data start point following these steps:

Figure 4-9.  Zoom View of Best Data Area.

Select Data Stop

The next step is to pick the end time (which is 600 in Fig. 4-7, p. 4-17):

Show Fit                The Show Fit button on the opening screen opens the Results screen, which contains four plots (see Fig. 4-10, p. 4-20). Plots A and B show actual and extrapolated data points and parts C and D show how equilibrium formation temperature was estimated.

Plot A

• Blue dots = tool measurement stations
• Unshaded region = data selected for processing
• Diamond = last third of the selected data
• Bold red line = reference model corresponding to the physical properties (shown in lower right plot)
• Dashed/dotted lines: extrapolated temperatures

Plot B

This plot shows the difference between data and model and reveals systematic deviations that cannot be recognized in the first plot. The deviations are plotted on a log-scale, as absolute values

• Open symbols = overestimates
• Solid symbols = underestimates

Figure: results screen

Figure 4-10.Results Screen. (MH draft has a better figure

Show Fit, cont.      Plot C

This plot shows a crossplot of measured and modeled temperatures. Early data appear on the upper right corner of the plot and later data appear toward the lower left corner. Extrapolation of the (hopefully) linear trend shown in this plot back to the x = 0 value indicates the interpreted formation temperature at equilibrium (i.e., what the tool would have recorded eventually, if it were left in place long enough). Two values are indicated:

• Dashed pink line = use of the full data window
• Dotted black line = use of the last third of the data window (see part A)
• Black dotted line = standard deviation of the misfit between the model and observations
• Blue open circle (at ~70 s on the x-axis) = optimal time-shift used in the previous plots.
• Click on the axes to see dashed and dotted lines that show the sensitivity of estimated undisturbed formation temperatures to time-shift changes [Author: blue dot, dashed line, dotted line don’t show up well in this jpeg-MG suggested a different data set.]
• Click the time-shift axis to inspect the effect of different time-shifts on all graphs.
• Click the parameter box in the top left corner of part D to open a new window where model parameters k and rc can be changed by moving the crosshair on the displayed graph

Plot D

Make Report          The final step in these instructions is to make a report. You can send the results of the fit analysis to a text file for plotting with different software by clicking Make Report in the opening screen. Make Report creates .eps files of the current result and contour plots in the data directory and generates a simple ASCII report.

4.9        Tool Redress

Introduction            Notify the electronics technician, lab tech, or lab officer if supplies are needed.

Procedure: redressing the tool

To prepare the tool for redeployment, follow these steps:

4.10   Quickstart Deployment Guide

Overview                This quickstart guide section assumes the electronics frame is in the shoe, ready for deployment.

Procedure: deploy tool

To deploy the APCT-3 tool, perform these steps:

Procedure: data recovery

This procedure assumes the coring shoe is clean and open, and the electronics frame is accessible.

5.0   Tool Disassembly

5.1        Overview

Introduction            To preserve the life of the APCT-3 tool, it needs to be cleaned thoroughly after all tests are completed for a hole or site and stored in the cylindrical plastic holder with a screw-on top.

Disassembly and maintenance procedures for the APCT tool include:

• Disassembling and cleaning the tool components.
• Inspecting the Heat Flow Shoe for deformation

In this chapter

5.2        Tool Disassembly

Introduction            The Downhole Measurement Lab houses heavy, dirty, wet equipment from expedition to expedition. To keep the APCT-3 tools in good condition so they will last many years, clean up the tools and work area when all temperature measurements for a hole or site are completed.

Procedure: disassembling the tool

When all temperature measurements are completed, perform these steps:

Procedure: cleaning the Electronics Support Frame

When the tool has been disassembled, perform these steps to clean and store the Electronics Support Frame:

5.2      Tool Disassembly, Continued

Procedure: cleaning the Electronics Support Frame, cont.

Procedure: cleaning the Heat Flow Shoe

Once the Heat Flow Shoe and electronic components are removed, follow these steps for cleaning the shoe:

Procedure: cleaning the Heat Flow Catcher Sub

To clean the Heat Flow Catcher Sub, perform these steps:

5.3        Heat Flow Shoe Deformation

Introduction            The Heat Flow Shoe can become deformed or damaged during deployment. Inspect the Heat Flow Shoe after use, particularly if the Electronics Support Frame is difficult to remove from the shoe. Heat Flow Shoe deformation can damage the electronics. Downward force applied to a damaged Heat Flow Shoe can case seal failure and leaks, drowning the electronics.

Heat Flow Shoe deformation

There are two main types of Heat Flow Shoe deformation:

6.0   Key Documents, Tools, References

6.1        Overview

Introduction            Information related to the tool but not part of the assembly/disassembly instructions (e.g., specifications) is included in this chapter.

Missing drawings

If an assembly drawing is missing from this manual, print out a new one from Cumulus or from the ship server.

In this section        This section contains these topics:

6.2        Parts Lists

Overview                The APCT-3 parts lists are grouped by the following assemblies.

Note:The Electronics Subassembly drawing number OM0720 was assigned but currently no drawings have been provided by Antares.

OM0800                 The APCT-3 tool assembly consists of the following parts:

OM0720                 The Electronics subassembly has these two parts, which are the same parts in the APCT (see OM0801 in the ODP APCT Operations Manual). OM0720 is incomplete as Antares has not provided drawings. :

Figure 6-1.  APCT-3 Components with Part Numbers

Communications Cable

OM0722

Heat Flow Catcher Sub Body

OP4377

Top Ring OM0705

O-Rings OD2041

Heat Flow Shoe

OP4375

Electronics Support Frame

OM0720

O-Ring OD2147

O-Ring OD2151

O-Ring OD2039

O-Ring OD2041

6.3        Specifications

Measurement temperature range

The APCT-3 tool’s typical temperature measurement range is about –5°C to +50°C (nominal temperature resolution of the complete instrument is

<2.5 mK over a range from –6° to +55°C, and 1.0 mK at temperatures

<25°C.). The components of the tool have different temperature ranges:

• Two coin cell lithium batteries in the APCT-3 tool are rated to an absolute maximum of 50°C.
• Thermistor has a high temperature coefficient (~4% per degree change in temperature) from -80° to 100°C.
• Electronics can safely be operated at ambient temperatures from -10° to 60°C.

APCT-3

specifications

APCT-3 tool specifications are as follows:

• ATMEL 8 bit Microcontroller (AT90S2313)

—    2 Bytes of In-System Programmable Flash

—    128 Bytes of SRAM

—    128 Bytes of In-System Programmable EEPROM

—    Programming Lock fo Flash Program and EEPROM Data Security

• Lithium batteries provide 600,000 readings (i.e., continuous operation for ~1 week at a sampling rate of 1 s)
• Nonvolatile memory for as many as 65,000 readings, which preserves the recorded data even if there is a total loss of battery voltage
• Real-Time Clock
• 16-bit A/D converter (AD7705BR)
• Aged, glass-encapsulated thermistor (Model YSI 55032)

Limitations            The APCT tool has these limitations:

• Can only be used in soft sediments appropriate for piston coring.
• Can only be used in relatively stable sediments where danger of hole collapse is minimal.
• The upper temperature limit of the tool is 50° C.
• The tool is limited to depths at which the force required on pullout is within safe limits, usually the upper 120 m. This depth limit is somewhat less than the limit for regular APC coring because the sediments will “grip” the corer more tightly during a 10-15 minute temperature measurement than during the much shorter time required to collect a core.
• Cannot be used when high overpulls indicate a risk of losing the tool if the shoe remains in the sediment for a prolonged time.

6.4        Calibration Summary

Overview                All temperature calibrations preformed in the IODP-USIO Metrology Lab are comparison calibrations. This means that a very stable and uniform temperature source is applied to both the unit under test (UUT) as well as a temperature standard which has been calibrated and is traceable to an NIST (National Institute for Standards and Testing) temperature standard. The output of the UUT is compared to the output of the standard at several different set temperature points throughout the UUT operational or limited range. These data are collected and archived as the primary calibration data, which may be used to calculate coefficients for various curve fitting equations such as the Steinhart and Hart equation.

Temperature standard

For the APCT-3 tool, the temperature standard is the standard thermistor read with a BlackStack thermometer readout and the temperature source is the 7012 High Precision Bath.

Process                 •  The APCT-3 is installed in the APC Heat Flow Shoe with an adapter that seals the electronics chamber but allows data communication with the APCT-3 tool.

• This assembly is then submersed completely in an oil bath.
• The standard thermistor is submersed in the bath in close proximity to the APCT-3 Probe.
• Ten temperature point data sets are logged and compared between the APCT-3 resistance measurements and the standard across the range of tool operation (0ºC to 60ºC at near 5ºC intervals) but no attempt is made to hold these intervals exactly (i.e. the 5ºC point may actually be 4.895ºC).
  • These data are curve fitted to the Steinhart and Hart resistance to temperature equation and coefficients are calculated.

Additional information

For more information about Calibration contact Dean Ferrell at ferrell@iodp.tamu.edu.

6.5        Development History

Overview                The APCT-3 tool is a third generation temperature tool. Measurements of in situ temperature have been made in oceanic sediments during scientific drilling since before the Deep Sea Drilling Project (DSDP) began (Von Herzen and Maxwell, 1964). New tools were developed and modified during DSDP (Horai, 1985; Uyeda and Horai, 1980]) and during the Ocean Drilling Program (ODP) (Davis et al., 1997; Fisher and Becker, 1993; Shipboard Scientific Party, 1992a), the successor to DSDP. In some cases, temperature tools were run during drilling programs to resolve specific geothermal, hydrogeologic, or paleoceanographic questions, but

in other cases, data were collected during routine operations even though they were not central to primary expedition goals (see summaries of DSDP and ODP thermal studies: Erikson et al., 1975; Hyndman et al., 1987; Pribnow et al., 2000).

Advanced Piston Corer Temperature Tool

Temperature measurement tools in scientific ocean drilling comprise a subset of third-party tool developments (designed, built, and tested independent of the primary scientific operator or its subcontractors) that have contributed to both the success and the enduring legacies of these programs. One of the most innovative downhole tool developments in the latest years of DSDP was a piston coring shoe with temperature- measurement capability (Horai, 1985; Horai and Von Herzen, 1985; Koehler and Von Herzen, 1986). This tool allowed DSDP (and later, ODP) personnel to determine in situ temperatures within the undisturbed formation well ahead of the drilling bit without making a dedicated tool run. These tools have been used successfully in many geological environments to evaluate thermal conditions within subseafloor sediments and in open boreholes. Although the piston coring system in DSDP was initially referred to as the HPC, subsequent improvements created an advanced piston coring (APC) capability. A temperature tool run with this system is herein referred to as an “APCT tool.” For more information on the APCT, go to the ODP Legacy manual Advanced Piston Corer Temperature (APCT) Tool Operations Manual.

Eight APCT tools based on the design introduced during DSDP were purchased by the ODP science operator (Texas A & M University [TAMU]) in 1984 and were used extensively during the early years of the new program. All of these tools were eventually lost or damaged over time, and by ODP Leg 117, it was necessary to begin building a new set of instruments. Second-generation APCT tool development was completed

in 1991. This tool system was designed and built on contract by a commercial engineering company, under the supervision of ODP personnel. The new tools were placed on the R/V JOIDES Resolution for use during Leg 139 and operated for more than 15 years. The second- generation APCT tools differed from first-generation tools in several important ways.