�������

������

�� ���������� ������������ ���

� !"#$%&'()*+,-

Geo-Log Ltd.

2

COMPANY PROFILE

Geo-Log Ltd provides geophysical logging and well inspection services for water well owners, drilling companies and different organisations dealing with geological projects.

The company was established in 1991 by Mr. Gábor Szongoth senior geophysicist and Mr. Zoltán Kasza senior field engineer, former employees of the Eötvös Lóránd Geophysical Institute (ELGI). For few years they worked in co-operation with ELGI, but in May 1998 the company seceded from the institute and from that time they work independently. Geo-Log is continuously growing, currently has 15 colleagues working in full time and numerous contracted specialists.

Geo-Log’s personnel are made up of senior specialists with long term experience in their field. Geophysicists, computer experts are working in well-organised team, processing and interpreting the logs to create clear and properly arranged reports for the Clients. Electronic and mechanical engineers support the field engineers calibrating periodically the tools and carrying out the maintenance and repairing works. Contracted experts complement the staff to solve specific problems.

Geo-Log Ltd. provides logging services for distinguished government projects. The company participated in scientific studies for assessing the impact of a planned new underground line on the thermal springs located under the Gellért hill in Budapest. Geo-Log Ltd was contracted to carry out the necessary geophysical logs for a newly constructed nuclear waste deposit of Hungary.

The quality is primary concern in the business strategy of the company. Geo-Log Ltd obtained the ISO 9001 certificate in 2003, and regularly renews it (at last in 2009).

Geo-Log Ltd.

3

LOGGING SERVICES Geo-Log Ltd provides a

wide range of logging and well testing services in various well- and borehole-conditions up to 3000m and 120ºC. Geo-Log is experienced in logging of exploration boreholes for general geological studies, solid mineral or coal mining; new and old water wells; and slime holes drilled for engineering and environmental protection purposes. The services are available either as complete studies including the field works and the complex interpretation of the measurements, or stand-alone logs upon request of the Customer.

Logging of exploration bore holes

Complex geophysical logging program is offered for the most different types of open and cased exploration boreholes to determine the nature of the penetrated geological units, their lithological and/or mineralogical composition and their relevant geophysical parameters. Geo-Log Ltd provides this service, among others, for general geological mapping, metallic, non-metallic and coal-mining projects. Special measurements are offered for dry holes.

Determination of fractured zones

Geo-Log Ltd.

4

Logging and testing of water wells

The logging and testing of piezometer- (monitoring), supply-, and thermal water wells, and those for the use of geothermal energy is the primary field of Geo-Log’s activity.

Services for new wells

• Exploration phase: Complex and optimised logging and testing program in open (pilot) hole before running the casing and the screens into the well in order; – to locate the water bearing zones, aquitards, and aquicludes, – to characterize the aquifer, (clay content, temperature and salinity of the ground water), and – to provide information on the geometry of the borehole. (well path, cavernosity) (In case of unstable formations some of the logs, like, for example, those which involve the use of radioactive sources, are not run.)

• Construction and development phase: Providing information on the condition of the borehole, the casing and the screen both, during and after the completion of the well construction works. Checking the condition of the cement sheath or other sealing materials behind the casing and of the gravel pack in the annular space.

• Final acceptance: Checking the result of the well development. Detecting thief zones, cross-flow. Locating of the inflow, analysing the distribution of the production over the screens, including static and dynamic tests. (See also Hydraulic Tests.)

The services help the well constructor to carry out his job according to the actual geological and borehole conditions, and provide information for the Owner about the quality of the works performed and the conformity of the actual well parameters with the planned ones. According to the international practice, the final acceptance of the finished ground water wells is based on geophysical control measurements.

Interpreted logs in a clayey-sand sequence, indicating the porosity, the clay and sand content of the formations and the recommended intervals for screening.

Determination of aquifers

Geo-Log Ltd.

5

An application of the full wave sonic log for gravel pack inspection. In the marked interval there is no gravel behind the screen.

A full wave sonic log used for checking the bonding of the cement.

Gravel pack inspection

Cement bond evaluation

Geo-Log Ltd.

6

Full wave sonic log verifies the actual location of the screen in a newly built well. Flow rate and temperature logs indicate cross flow between the upper and lower aquifer. Flow rate log, recorded while pumping, shows the distribution of the production over the screens.

Cross-flow detection

Geo-Log Ltd.

7

Inspection of old wells After long-term operation water well may have defects and consequently may need

remedial works. They should be properly planned to guarantee their effectiveness. The well inspection program provides the necessary information on the condition of the well for planning. It reveals:

• the actual well structure and depth

• the damages of the screen and the casing (if any)

• the location where sand, clay or other contaminant enter into the well

• the deficiency of the gravel pack and the cement sheath

• the existence of cross flows between production intervals Similarly like in case of new wells, the logging service includes the control of the

remedial works, providing information for both the Constructor and the Owner.

Inspection of an existing well. – Caliper and magnetic susceptibility logs revealed parted and missing casing. Flowmeter, temperature and fluid resistivity logs shown water inflow at a depth, where casing was supposed to be installed. Televiever image confirmed the existence of open fractures at the same depth. (red arrow)

Well structure according to

the documentation

Well structure according to

logs

Well structure after the remedial works

Fractured zone in the open

hole

Geo-Log Ltd.

8

LOGGING METHODS Geo-Log Ltd performs a wide range of logging methods. The applied log combination

is always selected to provide the maximum information for a reasonable cost. The available logs cover a wide range from simple traditional methods, like the well-known electric survey, to the sophisticated high-tech imaging logs.

The available log types

1. Apparent resistivity (normal and guard)

2. Micro resistivity

3. Spontaneous Potential (SP)

4. Conductivity

5. Magnetic susceptibility

6. Natural Gamma Ray, Spectral GR

7. Density

8. Neutron porosity

9. Full wave sonic log

10. Caliper (3-arm)

11. Temperature, diff. temperature

12. Deviation (Inclination/Azimuth)

13. Acoustic televiewer (Transit time / Amplitude)

14. Optical televiewer (Optical image of the borehole wall)

15. Flowmeter (impellor and heat pulse)

16. Fluid conductivity

17. Optical transparency

18. Pressure

The above logs are generally recorded by combined tools. For example our caliper tools have a temperature and gamma ray sensor as well. The following list contains our tools and the physical quantities what they measure.

3D presentation of acoustic televiewer image log

Geo-Log Ltd.

9

DOWN-HOLE TOOLS 1. Passive electric tools

Measured quantities: the apparent electric resistivity of the formations and the spontaneous potential. Derived quantities: In case of no invasion (boreholes drilled with formation water or impermeable formations) the true resistivity can be calculated. In case of boreholes drilled with formation water the porosity can be estimated from the true resistivity and the formation water resistivity . The later can either directly measured or estimated. Dimensions and spacing: They are available of 40, 50 and 60 mm diameter versions. Bigger and heavier tools are used in deep holes with heavy mud. Apparent resistivity is measured by normal electrode configuration with 10, 40 or 40, 160 cm electrode spacing. Shorter spacing is advantageous in small diameter boreholes while the longer one is recommended in bigger diameters or in presence of very conductive mud. Conditions and Restrictions: The minimum borehole diameter is 59 mm and it should be filled with conductive fluid (water or mud). Usage: Resistivity logs are routinely used to locate lithological boundaries and water bearing intervals. In boreholes drilled with fresh water the spontaneous potential log rarely provides useful information.

2. Micro resistivity tools Measured quantities: the apparent resistivity near to the borehole wall. Derived quantities: non Dimensions and spacing: The tool body itself is of 43 mm, however the bow springs that hold the electrode make the tool wide, thus it can not be used in small diameter boreholes. The electrode spacing is 2.5 and 5 cm (1 and 2 inches). Conditions and Restrictions: The minimum borehole diameter is 200 mm because of the springs, the presence of conductive fluid is necessary. Usage: In case of drilling with mud the logs will show different values where mud cake has built up, e.g. where the formation is permeable. Used occasionally as a qualitative auxiliary log.

3. Induction tools Measured quantities: the apparent electric conductivity of the formation, which is the reciprocal of the electric resistivity. Its measuring range is limited; however it can be useful in dry or plastic cased holes. Derived quantities: apparent electric resistivity Dimensions and spacing: The tools are of 43 mm diameter. Conditions and Restrictions: It can not be run in steel cased well or in presence of very conductive mud. Minimum borehole diameter is 59 mm. One version measures the magnetic susceptibility as well. The susceptibility log is used as qualitative indicator to distinguish formations of different lithology or to locate steel centralizers behind plastic casing. Usage: Used in special cases, like dry or plastic cased holes as an auxiliary log.

4. Combined caliper tools Measured quantities: Borehole or casing internal diameter, temperature and gamma ray Derived quantities: Borehole and/or annulus volume, differential temperature

Geo-Log Ltd.

10

(temperature gradient) Dimensions and spacing: The tools are available of 36 and 43 mm diameter versions are the mostly used tools. Conditions and Restrictions: The minimum borehole diameter is 59 mm, while the maximum is about 600 mm depending on the mud. Very dense and viscous mud may be a problem, the arms tend not to open completely, providing inaccurate readings. Usage: The borehole diameter is essential information that is used for many purposes. Among others it is used for correcting other logs, to decide whether the borehole is suitable for casing installation etc. The derived borehole or annulus volume helps to plan cementing and gravel packing. The temperature log and its gradient tell a lot about the flow pattern in the well. Gamma ray is a basic log used to locate lithological boundaries.

5. Gamma tools Measured quantities: gamma ray only. These special tools are designed for special tasks. Some of them are more sensitive than the standard versions to measure small differences of the gamma ray intensity; some others are designed to be used in very active environment like uranium deposits for example. Derived quantities: Radioactive material content based on field calibrated empirical formulas. (not regularly) Dimensions and spacing: The tools are available of 36, 43, 60 and 76 mm diameter versions. Conditions and Restrictions: The minimum diameter varies from 59 mm to 96 depending on the tool diameter. The basic calibration is for water filled borehole, but corrections are available for mud and steel casing. Usage: These tools are used on special project for special tasks

6. Gama-Gamma density tools Measured quantities: apparent density which is equal with the true bulk density of the formation when the average Z/A ratio is nearly 0.5. The calibration is made in limestone test pits so the lithological correction is generally very small in sedimentary sequences; however it can be significant in formations which are rich in heavy elements. The tools are equipped with a motored are that press the tool against the borehole wall. The same arm measures the borehole diameter, which is used to correct the density data. Most of our tools are equipped with a gamma ray sensor as well, which may help to correlate the density log with other logs provided by a third party. Derived quantities: porosity, supposed that the density of the fluid that fills the pores is known Dimensions and spacing: They are available of 43 mm version. Conditions and Restrictions: The minimum diameter is 59 mm, in cased or dry holes qualitative logs only. NOT run in unstable formations. Usage: Geological exploration projects, coal mining, deep thermal water wells.

7. Neutron-Neutron tools Measured quantities: apparent limestone porosity that may slightly differ from the actual true porosity of the formations. They are equipped with a gamma ray sensor for correlation purposes. Derived quantities: True porosity Dimensions and spacing: They are available of 43 mm version. Conditions and Restrictions: The minimum borehole diameter is 59 mm, in cased or

Geo-Log Ltd.

11

dry holes qualitative logs only. NOT run in unstable formations. Usage: Geological exploration projects, deep thermal water wells.

8. Full wave sonic tools Measured quantities: The tool records the full wave train that propagates from the transmitter to the receiver. Derived quantities: From the wave train several log can be derived like transit time of the first arrival, amplitude of the first peak etc. Depending on whether the tool is run in open hole or in cemented casing other logs can be calculated from the transit time and the amplitude, like formation velocity or bond index. Dimensions and spacing: They are available of 43 mm version. Different types are used in shallow and deep wells. Conditions and Restrictions: The minimum diameter is 86 mm. Usage: These tools are used for many different purposes. Velocity log reflects lithological changes and can be used to calculate porosity. The complex analyses of the full wave train results rock mechanical parameters. The bond index log is an indicator of the cementing quality. The tool is frequently applied in well inspections to locate screens.

9. Deviation tools Measured quantities: The inclination and azimuth of the longitudinal axis of the tool, which in turn is generally parallel with the axis of the borehole, thus the tool provides information on the well path. Azimuth data are measured on magnetic principles, thus they are false and therefore meaningless in steel casing. Derived quantities: True vertical depth, closure distance, 3D well path Dimensions and spacing: They are available of 40 mm version. Conditions and Restrictions: The minimum diameter is 59 mm. In steel casing only inclination data can be provided. Usage: Checking the verticality of the well, controlling the well path to find or avoid underground tartgets.

10. Sonic televiewer Measured quantities: the tool has a rotating head that transmit sonic impulses which propagate through the borehole fluid than are reflected back from the wall of the borehole. The transit time and the amplitude of the reflected impulse are measured. Unlike ordinary tools that provide one data at a certain depth point, the televiewer may provide up to 720 data obtained from different directions of the same depth. The recorded data is shown as a colour coded map, one axis is the depth the other is the unfolded circumference, while the colour code represents the measured quantity e. g. the transit time or amplitude. These kinds of logs are referred to as “image logs”. Derived quantities: Average borehole diameter, ovality, fracture and bed plane identification, statistics on fracture directions Dimensions and spacing: They are available of 40 mm version. Conditions and Restrictions: The minimum diameter is 59 mm. The presence of some fluid is necessary. Up to 70 °C. Usage: Geological exploration projects, well inspection.

11. Optical televiewer Measured quantities: Similarly to the sonic televiewer the tool has a rotating had, but instead of the sonic waves, it transmits light impulses which are reflected back from the borehole wall. The sensor detects the intensity and the colour of the returning light beam. The result is one image log (see above) that is a special image

Geo-Log Ltd.

12

of the borehole inner surface. Derived quantities: fracture and bed plane identification, statistics on fracture directions, from the colour image the nature of the materials that fills some fractures can be assess. Dimensions and spacing: They are available of 40 mm version. Conditions and Restrictions: The minimum diameter is 59 mm. They can work in clear water filled or dry boreholes. Up to 70 °C. Usage: Geological exploration projects.

12. Downhole video camera Measured quantities: It does not measure physical quantities, instead provides a perspective video record, same as can be made by ordinary video cameras. The special feature of the camera is that it is designed to be used in wells, its head can be rotated and tilted, and thus the operator can point it freely to the interesting objects. Derived quantities: non (The “log” is a movie in standard DVD format.) Dimensions and spacing: Without centralizers using the frontal light head its diameter is 87 mm, while with the annular light head its maximum diameter is 132 mm. Conditions and Restrictions: The minimum borehole diameter is 100 mm with the frontal light head, while 150 mm with the annular one. The camera works in dry holes or in wells in which the water is clear. The water clarity seriously affects the quality of the record. I can be used up to 60 °C and needs a special coaxial cable for data transmission. The tool itself is rated to 100 bar (1000 m) however it resists that pressure at 20 5C only. Another issue is the cable. The longer the cable the bigger the necessary diameter. At the moment Geo-Log has a winch dedicated to the camera and equipped with 500 m special cable. Thus the maximum depth that can be reached with camera is about 470-480 m. Usage: The video camera is quite popular among our Clients. It is used to find and identify foreign objects left or dropped in the well, and to check the condition of the screens and the casing after construction a new well or before and after of any operation in case of old wells.

13. Combined flowmeter tools Measured quantities: Rotational speed of the impeller (rpm), temperature, fluid conductivity, pressure, optical transparency. (Four of the above five quantities can be measured at once. The tool has two operating modes; in one of them it measures the rotational speed, temperature, fluid resistivity and optical transparency, while in the second mode the pressure and the temperature are recorded. The operator can switch between the operating modes without removing the tool from the well. Derived quantities: Flow rate expressed either in meter/min or liter/min, temperature gradient, pressure gradient. Dimensions and spacing: The tool is available of 43 mmm version. Conditions and Restrictions: Minimum borehole diameter is 59 mm. Pumping is necessary to obtain flow rate log that characterize the operational conditions. Usage: It is regularly used for well inspection both in new and old wells. Water supplier companies ask to check their wells at every three or four years to see how the filters work and to discover flow anomalies like leaking casing for example.

14. Heat pulse flowmeter Measured quantities: The measuring principle is the following: A heater grid is positioned on the halfway between two thermo sensors. The heater generates a heat pulse that propagates in the fluid to the thermo sensors. If the fluid does not move

Geo-Log Ltd.

13

the heat pulses arrive at the same time to both sensors, however if the fluid moves, the heat pulse that propagates along with the moving fluid arrives earlier than its counterpart. From the difference of the two arrival times, the fluid velocity can be calculated. The tool works on station by station basis, e.g. it does not provide a continuous log. Instead it is stopped at those depth points where the flow rate is to be measured than it is made to operate with a surface command. The result is flow velocity expressed in m/min Derived quantities: Flow rate expressed in liter/min. Dimensions and spacing: It is of 43 mm diameter. Conditions and Restrictions: Minimum borehole diameter is 59 mm. Usage: It has been designed and intended to detect very weak flows. It is used in environmental protection project to detect weak in- or outflows.

15. Pressure tools Measured quantities: Pressure and temperature. Derived quantities: Temperature gradient. Dimensions and spacing: The tool is available of 43 mmm version. Conditions and Restrictions: Minimum borehole diameter is 59 mm. Usage: It is used in those cases when the combined flowmeter is not necessary like, for example, in case of bubble point determination in thermal water wells. In some particular cases they are also used as down hole pressure monitoring sensors.

16. Memory Gauges They are special versions of the pressure tools. Unlike conventional tools, they do not need a power supply from the surface, neither ttransmit data. Instead they have their own internal battery and memory. Lowered to the well they can be left there for long time and acquire data according to a predefined program. Retrieving it from the well the recorded data can be downloaded for further analyses. Measured quantities: Pressure and temperature. Derived quantities: non Dimensions and spacing: Geo-Log has different types, but they are all slim. Their diameter is not bigger than 22 mm. Conditions and Restrictions: Different tools have different pressure and temperature range. We have devices for deep and hot wells, too. Usage: They are used in long term measuring programs like long pump tests or well interaction inspections.

17. Downhole water and gas sampler It is used to sample the water in wells right above the productive zone. Dissolved gases are separated at the surface.

Apart from the above listed logging tools Geo-Log has equipment for gas separation for thermal water wells. It consists of a separator tank, gas cooler, condense water separator, in-line flowmeter for both water and gas, pressure and temperature sensors and data acquisition system.

Geo-Log Ltd.

14

EQUIPMENT Geo-Log started to provide the logging service with equipment designed and

manufactured by ELGI, but in the last ten years, new state-of-art equipment was bought from Western European and North American manufacturers. In addition Geo-Log itself develops new equipment. (Our five-parameter combined flowmeter probe is an especially effective tool for water well inspection.) To answer the increasing demands, new logging units were also built. At the moment five units are in operation. Three of them have capacity up to 1000 m, one is able to provide service up to 2000 m, and the fifth is equipped with 3200 m seven core cable for very deep wells. The downhole tools measure two, three or four parameter simultaneously, reducing the number of the necessary runs, thus the total logging time. Geo-Log performed, and currently does as well speciallogging jobs in tunnels. A special, portable unit has been developed for underground logging.

Geo-Log uses two different type of data acquisition unit. Both of them is digital with flexible recording, printing and playback functions.

• One is the MOLE a microprocessor controlled logging equipment. The log records are available at the well site both digitally and as hardcopies. The digital record is in a MOLE-compatible binary format, but it can be converted to ASCII format at the well site, if so required. Printed field logs generally consist of two tracks, a 6cm wide on the left, and a 12cm wide on the right side of the paper. The depth data are presented between them. A special feature of the MOLE is that it is able to provide up to 4 hardcopies in real time. The copies are available in metric units only.

• The other is the ALT LOGGER made by Advanced Logic Technology, Luxembourg. That is a modern flexible unit allowing the operator to switch between metric and

imperial units. The number and the format of the log tracks are freely adjustable according to the request. The recorded file format is directly compatible with WellCAD and it can be easily converted to ASCII format.

Geo-Log Ltd.

15

INTERPRETATION A quick-look interpretation is made by the field engineers at the well site. The field logs

can be sent to the main office via GPRS connection and a preliminary report is provided to the Client within 24-48 hours depending on the actual conditions. The final report is normally ready within a week. It consists of a textual report, and a composite log, which contains the measured and calculated logs with the interpreted lithology and the derived parameters. In case of complex jobs, like well inspection, it is complemented with charts and photos and more detailed analyses of the observations. The final report is presented both in electronic form as Acrobat pdf file on CD, and as colour-printed hard copy. By request, the final report can be prepared in English. The number of the provided copies is subject of agreement.

The pre-processing and interpretation is carried out with Geo-Log’s own developed software, the MOLELOG (authors: Katalin Horváth, László Gosztonyi). It is suitable to handle all the logs recorded by the company, including the heat pulse flowmeter. Its latest version runs in the well known Windows environment. The graphical user interface makes easy to use it. All the usual log editing features, like depth matching, data editing, log filtering, using formulas for the calculation of new parameters, are available. Unique feature of MOLELOG is that comments and pictures can be linked to depth points, and modifying the depth scale they move together with the anomalies. The edited composite logs can be printed practically on any printer or converted to Acrobat pdf file. In Geo-Log’s daily practice 24 pin matrix printers are used for b/w copies and inkjets for coloured ones. Imaging logs are processed with the well-known WellCAD software.

Composite log with legend, a screenshot from MOLELOG.

Geo-Log Ltd.

16

WELL-TESTS Geo-Log Ltd performs different well tests (pumping tests), either as complements for

the geophysical logging, or as separate services. (Pumps or compressors are provided by the driller or well owner.). These tests may last for several months and can be extended to several wells.

Water supply wells

• Specific capacity determination. Qualitative characterisation of the water flow around the well. (Laminar, turbulent.)

• Recovery tests. Determination of transmissivity, permeability. Estimating well effectiveness and the radius of the depression cone.

• Water and gas sampling at the surface for further laboratory analysis.

Thermal water wells

• Specific capacity determination. (as above)

• Recovery test. (as above)

• Pressure gradient measurement. Determination of the bubble point for proper pump installation to avoid cavitations.

• Continuous gas separation with simultaneous measuring of pressure and temperature date in depth and et the well head.

• Water and gas sampling at the surface and in depth for further laboratory analysis.

Detailed reports are compiled about the performed tests and the results.

Pressure gradient log is derived from the directly measured pressure data for the determination of the bubble point in thermal water well

Bubble point determination