Borehole measurements at great depth

European Commission Directorate-General For The Information Society And Media Directorate-General For Research And Innovation

Description

Availability and limits of logging tools
Energy research
Nuclear energy and safety

Informations

• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-THE-INFORMATION-SOCIETY-AND-MEDIA-DI
• Nombre de lectures: 65
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

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Commission of the European Communities
energy
Borehole measurements at great depth:
Availability and limits of logging tools
Report
EUR 13341 EN Commission of the European Communities
energy
Borehole measurements at great depth:
Availability and limits of logging tools
R. Hanel
NLfB
Stilleweg 2
Postfach 51 01 53
D-W-3000 Hannover 51
Contract No JOUG-0001-D
18 May 1990
Report
Directorate-General
Science, Research and Development
PAHL FUROP BiLlioih.
NC> EUR 13341 EN 1991 Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
L-2920 Luxembourg
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting
on behalf of then is responsible for the use which might be made of
the following information
Cataloguing data can be found at the end of this publication
Luxembourg: Office for Official Publications of the European Communities, 1991
ISBN 92-826-2417-X Catalogue number: CD-NA-13341-EN-C
© ECSC-EEC-EAEC, Brussels • Luxembourg, 1991
Printed in France CONTENTS
Page
Summary V
1 Importance of deep boreholes and borehole logging 1
1.1 Geoscientific aspects 1
1.2 Economic aspects 5
2 Borehole logging under extreme conditions 9
2.1 Measurement principle of standard logging methods ... 9
2.2 Classification of boreholes and logging tools 46
2.3 Minimum requirements for logging tools and
logging units 49
3 Availability of winch and cable 51
3.1 Winch
3.2 Logging cable3
3.3 Cable head 60
4 Availability of borehole logging tools
4.1 Standard logging tools1
4.2 Borehole tools for tests and experiments 6
4.3 Memory tools4
5 Integrated evaluation of logging data with respect to
the use of borehole logging tools 65
6 Development requirement 7
Acknowledgement2
Bibliography3
Annex 1: Alphabetical list of abbreviations used by
service companies and institutes7
Annex 2: Equivalent logging tools of the service companies 8
in SUMMARY
The continental crust, supplying mankind with raw materials and energy but at
the same time endangering it with earthquakes and volcanoes, has not been
sufficiently explored. In the past two decades, therefore, major crust exploration
programmes have been started. Control of the results thus obtained, however, is
possible only by means of deep boreholes. An increasing number of boreholes
is now being drilled both for prospecting and for geoscientific purposes.
The knowledge to be gained from a borehole is obtained either from the rock
material recovered from it or from downhole measurements or, better, from both
these methods. For reasons of economy, generally only a few drill cores are
taken, and borehole measurements are performed instead. Deep borehole logging
is therefore especially important.
From the technical point of view, depths of 10 000 to 15 000 m are at present
under discussion. The deepest borehole, the Kola SG3 (USSR), has so far
reached approximately 12 150 m. The question arises as to what extent logging
tools, electric cables and winches are available to cope with these depths and the
expected temperatures.
Studies have shown that for winches with a power sheave or a capstan unit
virtually no limitations exist down to depths of 15 000 m. The same applies to
steel cables used for lowering the memory tools.
*
For electric logging cables the limit is about 300°C and 10 000 m borehole depth.
Owing to attenuation and characteristic impedance, problems are to be expected
with signal transmissions at frequencies of more than 10 kHz, but these can be
alleviated by appropriate selection of the wires available.
Boreholes can be subdivided into normal (0 to 5 000 m), deep (5 000 to
10 000 m) and superdeep (> 10 000 m) boreholes. The borehole logging tools
are classified, according to the likely conditions of use, as tools for Normal
Environment Logging conditions (< 175°C, < 1350 bar), Hostile Environment
Logging conditions (175 to 260°C, 1350 to 1700 bar) and Very Hostile t Logging conditions (> 260°C, > 1700 bar). For Normal Environment Logging (NEL) conditions almost all known borehole
logging tools can be used. For Hostile Environment Logging (HEL) conditions
and particularly for Very Hostilet Logging (VHEL) conditions,
research and development is essential for the following tools for up to about
300°C and a depth of about 10 000 m:
- Azimuth and Inclination Tool for determining the orientation and
inclination of boreholes;
- Sonic Digital Tool (SDT);
- Dual Laterolog (DLL) for electrical measurements;
-l Induction Log (DIL) for electrical conductivity measurements.
It would also be desirable to have:
- Borehole Televiewer (BHTV);
- Formation Micro-Scanner Tool (FMST);
- Mechanical Sidewall Coring Tool (MSCT);
- 3-component Geophone;
- Geochemical Logging Tool (GLT).
As the upper temperature limit for borehole logging tools is pushed higher and
higher, development costs rise exponentially. For temperatures above 300°C the
aim should therefore be to use memory tools. The advantage of these tools is
that all the electronics can be better protected against heat in a Dewar. Also,
since data transmission is no longer required, less energy is produced in the tools
and self-heating is reduced.
For temperatures > 300°C and depths to about 15 000 m there is an urgent need
for research on the following memory tools:
- Caliper Tool (CAL);
- Gamma Ray Tool (GR);
- Litho-Density Tool for density measurements (LDT);
- Sonic Tool (BHC).
New and further development of these logging tools is likely to take place only
if the service companies can see a potential market for them. Experience has
shown, however, that latent development work can be stimulated by suitable
research and development projects.
VI 1 — Kola SG-3; 2—Timan-Pechora; 3 - Krivoi Rog; 4 - Dnieper-Don; 5 — Kuban; 6 — Saatly;
7 -Urals; 8 — Caspian Area; 9- Muruntay; 10-Norilsk; 11 —Tyumen
Figure 1.1 Superdeep boreholes and deep seismic profiles