The Adaro coal deposit is located on the northeastern border of the Barito Basin, a broad cratonic depression up to 250 kilometers wide, of Eocene to Pliocene age in the Tertiary period. The basin occupies much of the province of Central Kalimantan and the western part of South Kalimantan and is bordered to the west by the Sunda Shield and to the east by an upthrust belt of basement rocks which form the Meratus range.
The main coal bearing sequence in the Adaro area is the Warukin Formation which is divided into three sub units with the principal coal horizons occurring in the uppermost sub-unit.
Local Geology
Up to 13 seams can be recognised within a single deposit which are lenticular in development but which also vary in thickness due to converging and splitting. Individual seams may be up to 50m thick. Although the coals are characteristically low in ash there is regional and stratigraphic variation in rank and therefore in calorific value.
The coals with the higher CV (+ 5000 Kcal as received) occur in the Tutupan area with highest values occurring in the lower seams in the sequence. The coals in the Wara deposits to the west and south west have higher moisture (+35% adb) and consequently lower calorific values.
Coal Deposits
The Tutupan coal deposit stretches for a length of 20 kilometers along a ridge in the north eastern part of the Adaro area. No major faults are known to disrupt the coal. The deposit contains thirteen individual seams with the majority of the coal occurring in the T100, T200 and T300 seam groups. The thickest coal (50 meters) occurs in the T100 seam in the southern part of the deposit. The T200 seam is the principal seam in the north where it is also up to 50 meters thick.
The Wara 1 coal deposit is located 5 kilometers west of the Tutupan Central area. It is separated from the Tutupan deposit by the Dahai thrust. The deposit stretches in a north-easterly direction over a distance of 12 kilometers and dips to the southeast at 45°. The Wara 1 deposit is composed of three major seams which are characteristically low in ash (less than 3%) but with moisture contents of around 40%.
The North Paringin coal deposit lies to the southeast of Tutupan and around 1 kilometers north of the old Paringin Pit. The deposit forms an asymmetrical anticline of 4 kilometers strike length with the eastern limb dipping at 30° and the western limb at 60°. It is also a multi-seam deposit consisting of over 40 seams ranging in thickness from less than 5 meters to greater than 20 meters. The quality of North Paringin is similar to Tutupan with ash around 3% and CV gar of around 4800 kcal. The Paringin coal deposit extends south of the Balangan River.
RESERVES AND RESOURCES
Below is an excerpt from the Independent
Statement on the Coal Reserves and Resources by
Terence Willsteed & Associates:
Terence Willsteed & Associates (TWA) have been
requested by PT Adaro Indonesia to provide an
Independent Statement of Coal Reserves and
Resource as at 31 December 2010, located at
the Adaro Coal Operations in Kalimantan to be
submitted to the Jakarta Stock Exchange (JSX).
TWA have previously reported on the Adaro
operations and coal assets in the Independent
Technical Report on the Coal Assets of
PT Adaro Indonesia dated 29 February 2008, in the
Independent Technical Review of the Coal Assets
of New Hope Corporation, 31 July 2003 and in the
Independent Statement on the Coal Reserves and
Resources of PT Adaro Indonesia, December 2008,
dated 13 March 2009.
The Statement has been prepared independently and in accordance with the Code for
Reporting Mineral Resources and Ore Reserves (JORC Code 2004) of the Australasian
Institute of Mining and Metallurgy (AusIMM). This Code sets out the principles and
guidelines, which should be followed in the preparation of an expert report concerning
mineral resources and reserves. We believe all material facts are presented and that our
analysis is sufficient to meet the transparency requirements of the Code.
The Statement is required to assess that sufficient Reserves exist to meet the long-term
production plans and to confirm the overall resource estimates by Adaro and determine
that the mines have geological and structural conditions, which can be operated
successfully.
The Coal Resources and Reserves of PT Adaro Indonesia are based on a report from
Terence Willsteed & Associates dated 5 April 2011 and are estimated as at December
2010 as follow:
LOCATION
RESOURCES
Measured
Indicared
Inferred
Total
Tutupan
775
814
865
2455
North Paringin
117
96
85
299
Wara 1
492
366
449
1307
Wara 2
133
134
100
368
Total
1,518
1,410
1,500
4,428
LOCATION
Run Of Mine (ROM) RESERVES
Probable
Proven
Total
Tutupan
141
410
552
Wara 1
98
289
386
Total
239
699
938
Coal Samples for Quality Control
In-fill drilling and collection of core samples for quality analysis continues in the Tutupan pit.
EXPLORATION ACTIVITIES IN 2010
Exploration drilling activities were conducted in 5 areas in 2010 : Wara 1, Tutupan Pit, South Tutupan, North Paringin and South Paringin.
Exploration drilling continued in Wara 1. Additional cored holes were also drilled to augment the quality database for Wara 1 especially down dip.
At Tutupan Pit, in-fill drilling was conducted to refine the coal model especially down dip. In South Tutupan, additional drilling was conducted to check the geologic structure and core samples were
collected for coal quality analyses.
At North Paringin, the exploration program covered most of the low dipping eastern limb of
an asymmetrical anticline defining the structure Stratigraphy core samples were collected for coal
quality. Inclined holes were also drilled into the steeper dipping western limb. This activity will
continue in 2011.
LOCATION
No. Of Holes
Meters
Open Hole
Cored
Total
Open Hole
Cored
Total
Wara I
20
14
34
2,574
3,008
5,582
Wara II
10
2
12
886
212
1,098
Tutupan Pit
10
3
13
2,737
918
3,655
North Paringin
134
36
170
20,082
3,925
24,017
South Paringin
79
19
98
11,439
1,439
13,368
Total
253
74
327
38,208
9,513
47,721
LOCATION
No. Of Holes
Meters
Open Hole
Cored
Total
Open Hole
Cored
Total
Wara I
26
4
30
1,899
508,5
2,408
North Paringin
178
178
24,600
24,600
Total
204
4
208
26,499
508,5
27,008
At South Paringin, reconnaissance drilling was conducted at 1 kilometers
sections and 200 meter spacing to define the structure and coal stratigraphy.
Core samples were also taken for analyses. A preliminary model will be
made and the economic viability of the deposit shall be assessed to
determine whether further detailed drilling shall be carried out.
During the year, geotechnical core drilling was also conducted in Wara
1 and North Tutupan to collect rock samples for strength analyses. The
results will be used in the pit wall designs in these new areas. Piezometers,
inclinometers and water wells were also drilled as part of the geotechnical
monitoring and groundwater depressurization programs at Tutupan and
Wara pits.
Exploration and geotechnical drilling activities are outsourced to PT Asia
Drill Bara Utama and PT Trikarya Intidrill Persada under close supervision
and monitoring by Adaro Indonesia's Geology Department.
During 2010 the total cost of exploration activities was US$2.15 million
which is detailed as follow:
