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日本地熱学会誌第 41 巻　第 2 号（2019）45 頁～ 51 頁

J. Geotherm.Res. Soc. JapanVol. 41. No. 2（2019）P.45 ～ P.51技 術 報 告

High Pressure-High Temperature Well Logging and Measurements as an Emerging Technology for Geothermal Development

Tae Jong LEE ＊

（Received 9 August 2018, Accepted 18 January 2019）

AbstractTemperature of geothermal fluid or reservoir is directly related to the economic feasibility in a geothermal

system. High temperature geothermal systems (T > 250°C or higher) are mostly associated with active volcanics. Volcanic-related geothermal systems represent a significant potential energy resources. Some countries with volcanic activities are trying to develop extremely high temperature from supercritical or ductile regions, such as IDDP and DEEPEGS projects in Iceland, DESCRAMBLE project in Italy, JBBP project in Japan, and HADES project in New Zealand. Exploitation of such supercritical geothermal system demands novel downhole logging tools, which can give valuable information on the formation properties, inspection of well completion, and reservoir characteristics. In this work, high temperature and high pressure logging tools were firstly reviewed; not only that are currently available on the market from tool developers and service companies, but that are being developed by different project worldwide, and finally discussion on the future tool development was done. Future tool designs will strongly rely on the available material and further material improvements when they become available. Currently some advanced tools tolerating up to 260°C and PT sensor can now be measured up to 300°C in unshield condition and expected to reach the IPGT’s target temperature of 600°C in the near future with the aid of advances in new electronics materials and active heat shielded technology.

Keywords: geothermal energy, high temperature, high pressure, logging tools

＊　 Korea Institute of Geoscience and Mineral Resources, Daejeon 34132, Korea

©The Geothermal Research Society of Japan, 2019

1.IntroductionGeothermal developments nowadays are characterized

by ‘deeper’ and/or ‘hotter’, and ‘efficient’ systems. Many countries are prone to develop deeper part of the underground to get higher temperature from enhanced geothermal system (EGS) technologies and some countries with volcanic activities are trying to develop extremely high temperature from supercritical or ductile regions (Reinsch et al., 2017;

Dobson et al., 2017); such as Iceland Deep Drilling Project (IDDP; Elders et al., 2014) and Deployment of Deep Enhanced Geothermal Systems for Sustainable Energy Business (DEEPEGS; Fridleifsson et al., 2016), Japan Beyond Brittle Project (JBBP; Asanuma et al., 2012), Drilling in deep, SuperCritical Ambients of Continental Europe (DESCRAMBLE; Fridleifsson et al., 2016) project in Italy, and New Zealand Hotter and Deeper Project (HADES;

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Table 1

Country Company Web

Korea

Korea Institute of Geoscience and Mineral Resources (KIGAM)

http://www.kigam.re.kr/

Japan

Geothermal Energy Research and Development Co. (GERD)

http://www.gerd.co.jp/index-e.html

Germany Antares http://www.antares-geo.de/

New Zealand Hades Systems http://www.hadessystems.com/

USA

Schlumberger http://www.slb.com/

Bakers and Hughes https://www.bakerhughes.com/

GE Oil and Gas https://www.geoilandgas.com/

Tiger Energy services

http://tigerenergyservices.com/

Luxembourg Advanced Logic Technology (ALT)

https://www.alt.lu/

UK

Robertson Geologging (RG)

http://www.geologging.com/

Probe https://www.probe1.com/

Severn Subsea Technologies (Calidus Engineering)

http://www.severnst.com/ http://www.calidusengineering.com

Table 1  List of organization who provides  tools and/or  services  for HP/HT geophysical logging for geothermal applications

Bignall and Carey, 2011). Research trends in exploration, measurement and logging technologies are to follow exactly the needs in the geothermal development.

Most of the exploration, measurement and logging technologies for geothermal developments basically came from oil industries. But some higher or innovative technologies should be developed to be applied in such a demand in geothermal fields.

In this work, literature review has been firstly performed for the tools on the market that are currently available, and several efforts worldwide to develop tools for higher temperature conditions, and discussion about the future development is followed.

2.ToolsonthemarketAs the first step of reviewing the HP/HT (High Pressure/

High Temperature) tools, developers and/or service companies are firstly collected and listed as information sources on the geophysical loggings, especially for high temperature applications (Table 1). The list is limited only to the company who can provide HP/HT tools and service, but far from all of the service & development companies over the world.

Various kinds of logging tools can be applied to get difference information inside or near the borehole. One of most advanced service companies for HP/HT well logging is the Schlumberger, and Table 2 shows some examples of temperature and pressure rating for typical borehole tools in service by the company. Temperature and pressure rating is higher than 175°C and 103 MPa, respectively, for most of the sensors. Some sensors such as gamma-ray, sonic, and array induction image tools can be applied to higher temperature of 260°C, and even higher temperature rating of 350°C for the formation micro-imager tool (FMI-HD).

GERD, Japan had also developed HT/HP tools for many years, and currently have PTS and PT sensors in memory types that can tolerating up to 300°C or 400°C, respectively (Table 2).

3.TooldevelopmentprojectsReviewing what is commercially available and

beyond, several research projects have addressed the need for instrumentation for high temperature geothermal wells. Here, three different projects related to the HP/HT tool developments are introduced.

3-(1) The ZWERG projectThe main purpose of the project is to provide

standardized basic components, which are commonly used in many probes, such as probe housing, thermal insulation, design parameters, materials to those who are working on designing and developing many different kinds of logging probes and tools (Isele et al., 2015; Holbein et al., 2017). The term “ZWERG” came from the German translation of dwarf. It had been running since the year of 2010 by Institute for Applied Computer Science, Karlsruhe Institute of Technology (KIT), Germany.

The project developed many different modules or “bricks” as parts of logging probes, such as housing modules for uncooled space, housing module for the electronics, Dewar flasks (a vacuum insulation) and so on. It provides details of the design parameters and information on the materials, eventually a blue prints for each of the brick (Fig. 1).

As of 2016, development of the first tool GeoKam, a video inspection tool for deep geothermal boreholes, is almost completed (Spatafora et al., 2016). A laboratory evaluation test are to be performed in an autoclave simulated borehole conditions; which can simulate pressure up to 80 MPa and temperature higher than 200°C at KIT (Fig. 2).

Details on the description of each modules can also be

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Table 2

Schlumberger Sonde Temperature

(oC) Pressure (MPa)

Measurements

HIT, QAIT 260 172 Array Ininduction imager tools ARI 177 138 Azimuthal resistivity imager HRIA 150 103 High resolution laterolog array MicroSFL 177 138 Spherically focused resistivity

tool Microlog 177 138 Micro-inverse, normal CHFR-plus and CHFR

Slim 150 103 Cased hole formation resistivity

tool EPT 177 138 Electromagnetic propagation tool Gamma ray 260 172 ECS 260 172 Elemental capture spectroscopy QCNT 260 207 Compensated Neutron log tool APS 260 172 Accelerator porosity sonde RST 204 138 Residual saturation tool Litho-Density 260 207 CMR 177 138 Combinable magnetic resonance Sonic 260 207 FMI-HD 350 138 Fullbore formation microimager UBI 177 138 Ultrasonic borehole imager PressureXpress 204 138 Pressure CBL 260 207 Caliper tool 232 138 Flowmeter 200 103

GERD Sonde/Tool Temperature (oC) Pressure

(MPa) Measurements

Pressure/temperature/flow 300(6 hr)/350(4.5 hr) 35 SRO/Memory type Pressure/temperature 400 48 Memory type Downhole video 204 68 Downhole sampler 350 10.35

Table 2  Temperature and pressure rating of the tools for Schlumberger and GERD, Japan

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Fig. 12

Fig. 1.   Schematic diagram  for  the strategy and workflows of  the ZWERG project  (Figures provided by B. Holbein  (KIT), personal communication).

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Fig. 23.

Fig. 2  Schematic design of video  Inspection probe, GeoKam,  function model for 48 MPa and 165 ℃  (Figures provided by B. Holbein  (KIT), personal communication).

found in Spatafora et al. (2016). The GeoKam provides many important components, which can be universally used for development of probes.

The reason why this project is special is that it is basically open source (open hardware) project. It provides open sources or platform, bricks, which can be used universally for the downhole tool developments. The platform allows a cost effective and faster integration of additional modules, which in turn can be another unit (brick) of the platform.

3-(2) The DESCRAMBLE projectThe ongoing project DESCRAMBLE, one of the

European Horizon 2020 projects, will deepen a well in Larderello, Italy, down to 3-3.5 km to get geothermal water in a supercritical conditions (>374°C, >22 MPa) with a maximum temperature of 450°C.

There’s no logging tools commercially available so far to measure the well temperature and pressure at the expected reservoir conditions. One example is the electronic K10 P&T logging tool, from Kuster Co. which has a maximum temperature rating of 350°C for 4 hours, and GERD had developed PT sensor with temperature rating of 400°C.

Due to a lack of logging tools that can withstand the extreme temperatures expected, the DESCRAMBLE project is developing a new logging tool that measures P&T with a minimum of 8 hours operation at 450°C (Vedum et al., 2017).

The tool consists of pressure housing, heat shield (dewar flask), and inner parts with sensing and electronics located in the middle of the tool (Fig. 3). Almost all the electronic

components are rated for at least 225°C, the heat shield is rated to 450°C. Because there’s no wireline cable rated higher than 225°C, it is designed to a memory-type tool powered by high temperature batteries that can be deployed by a slick line cables.

A prototype has been verified in lab and field tests. Field test had been performed in Feb. 2017 in a well at Larderello with maximum temperature of 250°C. During the 6 hours of measurements, the electronics never entered high temperature mode as the internal temperature never exceeded the threshold of 70°C. The tool was also tested in a large industrial oven with temperature of 450°C for about 3 hours (Fig. 4). Using linear extrapolation, the tool has a dwell time of 6 hours at 450°C before reaching the internal temperature limit of the batteries (200°C).

DESCRAMBLE is still ongoing project and they will continue to improve the tools in reducing the tool diameter, higher temperature rating for the electronics and batteries, and improving performance of the heat shield.

3-(3) The HiTI ProjectIn the “HIgh Temperature Instruments for supercritical

geothermal reservoir characterisation & exploitation”(HiTI) project they developed instruments capable of logging reservoirs up to pure-water supercritical conditions (T<374°C), (Halladay et al., 2010; Ásmundsson et al., 2014).

A slickline tool (memory tool) tolerating up to 400°C measuring temperature, pressure, flow, and casing collar location for a few hours and wireline tools that can be operating long-term up to 300°C without heat shielding. This

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Fig. 34

Fig. 3.  The PT tool developed in DESCRAMBLE project (Vedum et al., 2017); The complete tool with pressure housing (top), heat shield and the nose of the tool (middle), and inner part of the tool showing the electronics in the middle (bottom). 

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Fig. 45

Fig. 4.  Lab  test of  the  tool;  internal  temperature versus  the maximum  rated  environment temperature (Vedum et al., 2017).

temperature limitation of logging tools was defined to comply with the present limitation in wireline cables (316°C; The Rochester 4-conductor wireline type 4-H-314M). Wireline tools including natural gamma radiation spectrum, borehole wall ultrasonic images signal were also developed and tested in the hot Icelandic geothermal wells. Dual laterolog electrical resistivity tool was also developed but could not be field tested as part of HiTI. Calidus Engineering Ltd., BRGM, and Advanced Logic Technology (ALT) were involved for downhole tool developments.

4.Discussion:futureinstrumentationAccording to the White Paper published by working

group in an international partnership on improving geothermal

techniques (IPGT; Ásmundsson et al., 2012), downhole tools for thermodynamic measurements will need to tolerate up to 600°C, while open hole formation tools such as seismic, acoustic and resistivity need to be upgraded to 300°C.

Future tool designs will rely on the available material and further material improvements when they become available. Most of ceramic encapsulated components are rated to 175°C, which is still the limit of many of commercially available high temperature tools. Advanced electronics is based on Silicon-on- Insulator technology (SOI) that can withstand up to 225°C. For even higher application, heat shields have to be attached to the tools.

Materials for next generation such as Silicon carbide (SiC) or diamond, which can tolerate over 500°C, have been

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invented, but the technology is not matured yet as much as SOI.

One of the major drawbacks of passive shields is that the thermal energy released by the protected electronics accumulates within the shield. Active cooling system, as developed in ZWERG and HiTI project, can be applied used with low power consumption and low emission of heat in the future.

Currently some advanced tools tolerating up to 260°C and PT sensor can now be measured in unshielded (barefoot) tools up to 300°C and expected to reach the target temperature of 600°C in the near future with heat shielded technology.

AcknowledgementThis work was supported by the Basic Research and

Development Project of the Korea Institute of Geoscience and Mineral Resources (KIGAM) and International Energy Agency (IEA) Geothermal TCP, WG 13 Emerging technology.

Special thanks to Dr. B. Holbein from Karlsruhe Institute of Technology and M. Hjelstuen from SINTEF Digtal for providing the figures.

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concept of  the Japan Beyond-Brittle Project  (JBBP)  to develop EGS reservoirs  in ductile zones, Geothermal Resources Council Transactions, 36, 359-364.

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Bignall, G.  and Carey, B.  (2011) A deep  (5 km?) geothermal science and drilling project for the Taupo Volcanic Zone – Who 

wants  in?, Proceedings New Zealand Geothermal Workshop 2011, New Zealand, 5 p.

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Fridleifsson, G.O., Bogason, S.G., Stoklosa, A.W.,  Ingolfsson, H.P., Vergnes, P, Thorbjörnsson,  I.Ö., Peter-Borie, M., Kohl, T., Edelmann, T., Bertani, R., Sæther, S.,  and Palsson, B. (2016) Deployment of deep enhanced geothermal  systems  for sustainable  energy business, European Geothermal Congress 2016, 8 p.

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Holbein, B.,  Isele,  J., Spatafora, L.  (2017) New downhole  tool designs for EGS based on platform development approach, GRC Transaction, 41, 2453-2469.

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技術報告

地熱開発の新技術としての高温高圧物理検層と坑内計測

リー・テジョン＊

概　要地熱貯留層の温度は地熱系の経済性に直接的に関係してい

る。250℃を超える高温の地熱系は、多くの場合が火山活動に結びついている。火山性の地熱系は、エネルギー資源として莫大なポテンシャルを有している。火山活動を有する国々の中には、超臨界または延性領域の極端に高温資源を開発しようとしている国があり、アイスランドの IDDP と DEEPEGS

プロジェクト、イタリアの DESCRAMBLE プロジェクト、日本の JBBPプロジェクト、ニュージーランドのHADESプロジェクトなどがある。そういった超臨界地熱系の探査には、地層の物性、坑井仕上げ状況、貯留層特性に関する貴重な情報を提供してくれる、新規の坑内測定ツールが必要となる。

本研究では、まず高温高圧の坑内測定ツールのレビューを行った。レビューは、既に市場に出回っておりツール開発業者か検層サービス業者から入手可能なものばかりでなく、世界の種々のプロジェクトにおいて開発中のものについても行った上で、最終的に将来のツール開発について議論を行った。将来のツール設計は、それが生産される時点において利用可能となる材料に大きく依存する。現状でも、いくつかのアドバンスド・ツールは 260℃まで耐えられ、PT センサーによってはシールド無しで 300℃まで耐えられるものがあり、近い将来の IPGT（international partnership on  improving geothermal  techniques）のターゲットでは、新電子機器材料の進歩によって 600℃の耐熱性への到達をめざしている。

キーワード： 地熱エネルギー，高温，高圧，坑内測定ツール