799P, in the north-eastern quarter of the Galilee Basin in central Queensland, ... is now located in Roma, Queensland, a distance of 370 miles (600km) from.
0807 Recent Coalbed Methane Exploration in the Galilee Basin, Queensland, Australia J. Read Holland, James K. Applegate – J. R. Holland & Associates, Inc. Malcolm Bocking – Bocking Associates CBM Pty Ltd ABSTRACT In 2007 Galilee Energy Ltd of Brisbane, Australia, initiated a detailed exploratory drilling program on the two contiguous exploration licenses, ATP 529P and ATP 799P, in the north-eastern quarter of the Galilee Basin in central Queensland, Australia. The licenses cover approximately 4,633 square miles (3 million acres), which consists of near flat grazing country, almost entirely underlain by thick coal seams which are deformed by several regional anticlines. Production of coalbed methane in Queensland was 86bcf (93PJ) in 2007 coming mainly from the Bowen and Surat Basins. The underexplored Galilee Basin covers 95,400 square miles (as large as Oregon) and is one of the largest remaining frontier basins in Australia with significant potential for coalbed methane. The inter-cratonic basin is filled with late Carboniferous (Pennsylvanian) to Middle Triassic sedimentary rocks including water bearing porous sandstones, the Early Permian age Aramac coal seams and the Late Permian age Betts Creek coal seams. The Galilee Basin is covered by the Jurassic to Tertiary Eromanga Basin. After a detailed review of the earlier coalbed methane exploration work in the Galilee Basin by Enron Australia Ltd, Beaconsfield Energy Developments Pty Ltd and Galilee Energy Pty Ltd, the data were deemed to be inconclusive and incomplete. In 2007, Rodney Creek #8, located approximately 40 miles (65km) northeast of Longreach, was drilled utilizing HQ wireline coring from 2942-3640ft (897-1110m), to obtain reliable consistent data. Gas desorption was conducted, at 161°F (72°C), on site for 5 days and for a further 85 days at a laboratory. The average gas content on a raw data basis was 150 scf/ton (4.7cc/g) and 184 scf/t (5.8cc/g) dry ash free. In situ permeabilities and stresses were measured taking great care that the packers were set to effectively isolate the seams being tested. The measured permeabilities measured range from 1 to 150 md with a weighted average of 30 md for the entire 24.9m (82ft) of gross coal thickness tested INTRODUCTION The Galilee Basin is a totally intracratonic basin located in central Queensland, (Scott et al 1995), as shown in Figures 1 and 2. This basin covers an area of
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approximately 95,400 square miles (247,000 square km). Barcaldine in the geographic center of the Galilee Basin is some 400 miles (640km) from the east Australian coast. The Tropic of Capricorn crosses near the east-west center of the basin hence it is now a subtropical climate with a summer-autumn wet season. Much of the basin is flat or gently rolling grasslands well suited for grazing livestock. Rainfall in the basin averages 16 inches per year but is irregular both in quantity and occurrence. The basin is crossed by numerous, mainly ephemeral waterways, and also by a few more permanent streams including the Thompson River which flows north to south through the central portion of the Galilee Basin. The basin has relatively thick Permian age coalbeds but these have not been mined in the past because of the depths and the distance to the principal markets. Coal exploration continues in potential open cut areas on the eastern margin of the basin. The nearest center for support services for oil and gas exploration and development is now located in Roma, Queensland, a distance of 370 miles (600km) from Barcaldine.
CHARTERS TOWERS
HUGHENDEN
WINTON
LONGREACH BARCALDINE
GALILEE BASIN
Figure 1. Location of the Galilee Basin, Australia. Figure 2. Features of the Galilee Basin including the eastern Koburra Trough, the western Lovelle Depression, the central Maneroo Platform and the southern Springsure Shelf. (Scott et al 1995). ATPs 529P and 799P are outlined in red
0
100
200 k
CHARLEVILLE
This basin is under-explored for oil, natural gas and coalbed methane. The northern part of the Galilee basin (north of 24o South) extends over some 60,000 square miles and contains only 60 wells including 13 drilled specifically for coalbed methane. Seismic coverage in the Galilee Basin is variable with only 17,000 miles recorded in the northern part of the basin until 1990.
GEOLOGICAL SETTING The Galilee Basin is a Late Carboniferous to Mid-Triassic sedimentary basin, located in the central west of Queensland, and extending northwest from the contiguous central Bowen Basin. The basin is very large, extending over 247,000 km2 and 2
being comprised of two main lobes which are joined in the north but separated in the south by the Maneroo Platform. The basin elements are shown on Figure 2. The Rodney Creek area lies in the north eastern section known as the Koburra Trough and it lies on the southwestern corner of that trough. The Koburra Trough extends over an area some 200km in diameter. As shown on Figure 2 ATP 529P and ATP 799P together cover about a quarter of the Koburra Trough. The Galilee basin strata comes to outcrop on the eastern and northeastern margins but is covered by more recent Eromanga Basin sediments in most of the remainder. The western area of the Koburra Trough is modified by a number of smaller fold structures such as the Rodney Creek Anticline. The eastern margins of the basin are reported to dip 0.5 to 3 degrees to the west (Carr 1975) and at Moray Downs, again on the eastern margin, 4.5 degrees to the west (Wells 1989). Seismic indicates the central region is relatively flat and the depth to the upper Betts Creek Coals is 3000 to 3600 feet (900 to 1100m) as shown on Figure 3. The seismic data supports the concept of continuous coals. The Galilee Basin is overlain by the Eromanga Basin of Cretaceous and Jurassic sediments and is largely underlain by the Drummond Basin of Carboniferous age.
Figure 3 Depth in meters to top of Betts Creek Coals, Galilee Basin (RISC 2004), in and adjacent to ATP 529 and 799
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STRATIGRAPHY The stratigraphic nomenclature used for the Galilee Basin in this paper is based on that used by Scott Beeston & Carr 1995, which is contained in Ward et al 1995 “Geology of Australian Coal Basins”, and is included in Table 1. Formations at the surface consist of the Allaru Mudstone and the overlying Mackunda Formation, both members of the Rolling Downs Group. Ephemeral water channels are filled with Quaternary alluvium. Quaternary sands and gravels form sheet like areas. Scattered remnants of the Tertiary Glendower Formation consist of quartzose sandstone, conglomerate and sandy mudstone. The Eromanga Basin overlies the Galilee Basin in the Rodney Creek area and the Early Cretaceous to Early Jurassic sequence consists of the Allaru Mudstone, a distinct Toolebuc Fm, the Wallumbilla, Hooray, Westbourne, Adoori and Birkhead Formations. The base of the Jurassic sequence is marked by the Hutton Sandstone. (Table 1) The Galilee Basin at Rodney Creek consists of 7 major stratigraphic units: • The Rewan formation is evident (but Warang, Clematis SS, Moolayember and Dunda Fms are not) - Triassic • Betts Creek Beds -Bandanna equivalent coal (R1 to R8) - Late Permian; • Peawaddy Fm and Black Alley Shale (marine sediments) – Mid Permian; are not clearly evident at Rodney Creek but a ‘condensed interval’ may exist in their place. These units are considered to onlap the Colinlea Sandstone. The Colinlea lies under the Betts Ck but may possibly be correlative with the Aramac Coal Measures. • Aramac Coal Measures – (R9?, A1 to A4) -Early Permian. • Jochmus Formation ( sandstone and tuff) – Early Permian; • Jericho Fm (sandstone and zeolite rich siltstone) – Late Carboniferous • Lake Galilee Sandstone The Rodney Creek boreholes have targeted the coal seams in the Betts Creek and Aramac Coal Measures. The first 5 of the above units are considered to be present but there is some disagreement in the literature in the placement of the Colinlea Sandstone with respect to the upper and lower coal sequences. The last two were not reached in the cored drillholes. The tentative assignment of stratigraphic units and the thickness of each unit as intersected at Rodney Creek and the Thunderbolt location in the northeast of ATP 529P, is presented in Table 1. The mid Permian that might normally separate these groups is either absent or consists possibly, of a thin ‘condensed interval’. The base of the Betts Creek Beds is ambiguous as several erosional contacts exist.
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Scott, Beeston and Carr (1995)
This report - Suggested stratigraphy - modified after Wells, 1989 and Day et al, 1982
Surficial deposits
274 13
11.6 36
11.6 24.4
565 592
173 27
242.9
206.9
Westbourne Adori SS Birkhead Fm
645 676 700 760
53 31 24 60
255.4 296.3 311.8 343.8
12.5 40.9 15.5 32
Hutton SS
846
86
389.2
45.4
576.7 707.1
187.5 130.4
881.6
174.5
Upper Permian 1049.6
168.1
Toolebuc Walumbilla Cadna-Owie Hooray SS
Moolayember Fm Triassic
Late Permian
Warang SS
Moolayember Fm
Clematis SS Dunda Beds Rewan Fm
Bandan a Fm Correla Black Alley tive Betts Creek Sh Beds Peawaddy Colinle Fm a SS
Clematis SS Dunda Beds Rewan Fm
Warang SS
Rodney Creek Seam (R1) Betts Creek Beds
DISCONFORMITY
Early Permian
25 36.16
914.49
7.33
1002.5
88.04
1004.2
1.71
1071.8 1110.2
67.56 38.4+
R 2 to R8
UNCONFORMITY R9
Bonder oo Beds
Not Presen t 871 907.16
Bandana Fm Correlative
Colinlea Sandstone Aramac Coal Measures
231.9 KB RL Depth to base kb Thickness
379 392
Allaru MS
Jurassic
216.17 GL Depth to Base Thickness 10 10
95
Mackunda Fm
Rolling Downs Group
APC Thunderbolt 1
Not Present 105
Winton Fm Early Cretaceous
Rodney Creek 8
A1 (?Black Alley Sh) A2 (?Peawaddy Fm)
Jochmus Fm
Joe Joe Group
Aramac Coal Measures
Crossmore Seam (A3 U,M&L) A4 Seam Jochmus
Jericho Fm Late Carboniferous
Lake Galilee SS
Oakleigh SSt
Jericho Fm
Late Carboniferous 1607.5
Lake Galilee SS
Basement TD
1110.2
1611.2+ 1611.2
Table 1 Preliminary Stratigraphic Interpretation of ATP 529P, depth in meters.
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557.8 3.7+
HISTORY OF GALILEE CBM In the early 1990’s Enron Exploration Australia initiated a coalbed methane exploration program across a very large exploration license, ATP 529, in the central portion of the Galilee Basin known as the as the Koburra Trough. The Enron exploration effort was reported at the 1995 Intergas Coalbed Methane Symposium in Tuscaloosa by Mike Herrington and M. J. Zebrowitz. Enron drilled a total of six slimhole exploration wells with coring and two additional wells (Rodney Creek #3 and Crossmore #2) in which production casing and pumps were set. Enron appeared to be optimistic about the coalbed methane potential of the Galilee Basin as reported in the 1995 paper. These results indicated that the Betts Creek and Aramac coal measures encountered and tested in their program were high volatile coals with gas contents averaging 90 scf/ton (
