ODP Technical Note 10


A. Purposes of This Manual

Downhole measurements are vital components of almost every leg of the Ocean Drilling Program (ODP). These measurements augment the two other primary forms of ODP technology, drilling engineering and core recovery and analysis, and provide information about the formations below the seafloor at in-situ conditions. ODP uses three main kinds of downhole measurements: wireline logs, formation testers and samplers, and borehole observatories. For each of these measurement and tool types, there are "standard" instruments developed within the Deep Sea Drilling Project (DSDP) and ODP structure, and "third-party" instruments developed by independent investigators. Some tools are a combination of these categories. Because the ODP is committed to addressing a variety of problems and operating in a wide range of settings, downhole tools have changed rapidly since the first edition of this Technical Note was published (Becker, 1988). The present need for an updated Technical Note is evidence of the strong ODP commitment to downhole measurements in general.

The ODP runs the most advanced suite of routinely used downhole instruments of any scientific project in the world today. These tools change frequently and rapidly in terms of design and capabilities, and downhole tools specialists sailing on the JOIDES Resolution are often confronted with a bewildering array of instruments and procedures. With the short time available between establishment of the ship schedule and the start of individual legs, shipboard scientists often do not have access to instruments, or even manuals, prior to sailing. The primary purpose of this manual is, therefore, to provide some guidance for scientists interested in those downhole tools that ODP routinely provides by describing several key aspects regarding these tools: requirements for advance planning, general procedures for shipboard operations, and basic methods for data interpretation. For many of the ODP downhole tools, fully detailed operating instructions written by the tool designers or manufacturers are available at ODP and on board JOIDES Resolution, and will only be briefly summarized here, emphasizing those factors that are important in planning and conducting measurements. Interested scientists should contact the Science Operations or Technical Support departments at ODP for additional, more detailed, information.

The purpose of this note is similar to that of the ODP Logging Manual, which describes the logging tools and scientific logging services provided by the Borehole Research Group (BRG) at Lamont-Doherty Earth Observatory (LDEO). Copies of the latest (1990) ODP Logging Manual are available from BRG. Worthington et al. (1987) wrote a brief, useful summary of the ODP logging facilities. In addition ODP recently produced a glossy booklet (Worthington et al., 1992) containing general information on ODP downhole measurements and examples of how these tools are applied to solve geological problems.

In this Technical Note, "ODP" will be used to refer to the ODP Science Operator at TAMU, and "LDEO" will refer to the ODP Logging Contractor. ODP and LDEO divide responsibilities for downhole tools in a general way as follows: LDEO is responsible for providing logs measured with tools run on the seven-conductor logging cable (or "wireline"), whereas ODP is responsible for those tools used with the drill string and/or the nonconducting coring line (or "sand line"). This division has become somewhat fuzzy over the last several years; contact ODP or LDEO to determine which organization is responsible for any particular tool.

Most of this Note consists of descriptions of the following types of measurements that can be "routinely" made with tools provided by ODP: (1) borehole- or pore-fluid sampling, (2) temperature measurements in sediments or in an open borehole, (3) permeability measurements using a drill-string packer, (4) orientation of advance piston core (APC) and rotary core barrel (RCB) cores, (5) borehole observatories (CORK's), and (6) sampling of soft to semilithified sediments and fluids under hydrostatic pressure (PCS). Many other types of measurements are possible, and several new tools are being developed by ODP and outside investigators. The final chapter of this manual describes some of the new tools now under development, and specifies the conditions that must be satisfied before ODP will assume responsibility for routinely providing new kinds of measurements.

The remainder of this introductory chapter summarizes the information that is essential to assure that the routine measurements provided by ODP can actually be made in a manner that satisfies scientific goals: (1) requirements for advance planning for measurements using ODP tools, (2) an overview of the tools routinely available from ODP, and (3) the compatibility of these tools with the various ODP coring and engineering systems.

To Introduction, Section B.
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