Galilee Basin. Galilee Basin Hydrogeological Investigations. Briefing to RAPAD Longreach, 16 May rpsgroup.com.au

Transcription

1 Galilee Basin Galilee Basin Hydrogeological Investigations Briefing to RAPAD Longreach, 16 May

2 The Galilee Basin Geologically & hydrogeological diverse sedimentary Covers 247,000 km 2 The Galilee Basin extends:» 700 km from Charleville in the South to near Charter Towers in the north; and» 550 km east to west from east of Emerald in the east to Julia Creek in the northwest. Petroleum exploration leases cover nearly the entire basin, but most active exploration is occurring in the northern region Significant coal development underway in eastern area north of Alpha

3 Galilee Basin study area Julia Creek Richmond Hughenden Charters Towers Winton Longreach Aramac Barcaldine Alpha Blackall Quilpie Charleville

4 Galilee tenements of interest

5 Galilee Basin surface geology

6 Stratigraphic Relationships & Groundwater Major alluvium / bed sands of inland rivers Rolling Downs Group (e.g. Winton Fm & Wallumbilla Fm) Eromanga Basin Cadna-Owie Fm Hooray Sst Adori Sst Galilee Basin - Triassic Hutton Sst Major Unconformity Clematis Group / Warang Sst Galilee Basin - Permian Major Unconformity Betts Ck Beds, Aramac Coal Measures etc.

7 Significance of the major unconformities The unconformities:» Mark the stratigraphic boundaries for the: Basement rock; Galilee Basin sediments; and Eromanga Basin sediments.» Mark major changes in erosional and depositional environments.» Influence the connections between aquifers. For example, the Moolayember Formation, a regional confining layer, underlies the basal Jurassic unconformity.» Define the Permian age sediment outcrop areas, which correspond to the GAB intake beds.

8 Generalised section A A

9 Section A Eromanga Basin Great Artesian Basin Galilee Basin Joe Joe Gp

10 Generalised section B B

11 Section B Eromanga Basin Great Artesian Basin Galilee Basin Hooray Sst Colinlea Sst Betts Ck Beds Joe Joe Group

12 Basal Jurassic unconformity structure contours

13 Mid-Permian unconformity structure contour

14 The challenge Develop a baseline understanding of groundwater resources within the Eromanga and Galilee Basin strata:» Identify the major aquifers; &» Identify the major confining units Develop an understanding of the groundwater flow regime:» Identify the barriers and linkages between the groundwater systems and the CSG production horizons. Develop a baseline groundwater quality data set

15 DERM Groundwater Database Search Statistic Value Units Number of bores with any DERM records 10,442 (bores) Number of bores on GBOF tenements 3,247 (bores) Number of bores with aquifer unit identified 6,828 (bores) Number of bores with aquifer unit identified on GBOF tenements 1,011 (bores) Number of bores with DERM yield records 2,090 (bores) Number of bores with depth DERM records 2,660 (bores) Number of standing groundwater level measurements 41,579 (number) Number of standing groundwater level measurements on GBOF tenements 2,428 (number) Number of bores with DERM standing groundwater level data 4,405 (bores)

16 DERM registered bores

17 QPED Exploration Wells Statistic Value Units Number of wells with any QPED records 370 (wells) Number of wells on GBOF tenements (1) 147 (wells) Number of wells with stratigraphic units recorded 258 (wells) Number of wells with QPED DST records 116 (wells) Earliest recorded drill date 1922 (year) Earliest recorded drill date on a GBOF tenement 1927 (year) Number of wells with reported DST water quality 29 (wells) (1) Value does not include recent CSG well.

18 QPED exploration wells

19 Intake bed springs The GAB recharge springs in the Galilee basin occur in association with the intake bed out crops and sub-crop areas.

20 General groundwater use The major unconformities can be used as a guide to where water bores will be tapping Permian age sediments vs. where water bores will tap Triassic age and younger sediments Permian age aquifers are tapped in the east Jurassic & younger age aquifers are tapped in the west.

21 Groundwater use Drummond Basin

22 Groundwater use Betts Ck Beds / Colinlea Sst

23 Groundwater use Rewan Fm / Dunda Beds

24 Groundwater use Clematis Sst / Moolaymember Fm / Warang Sst

25 Groundwater use Precipice Sst

26 Groundwater use Boxvale Sandstone

27 Groundwater use Hutton Sst

28 Groundwater use Injune Creek Group / Westbourne Fm / Adori Sst / Birkhead Fm

29 Groundwater use Hooray Sst / Gilbert River Sst / Mooga Sst

30 Groundwater use Wyandra Sst / Cadna-Owie Fm / Bungil Fm

31 Groundwater use Wallumbilla Formation

32 Groundwater use Allaru Mudstone

33 Groundwater use Winton Fm & Mackunda Fm

34 Groundwater use Tertiary age formations

35 Groundwater use Alluvium

36 Baseline groundwater level data Data sources:» Water bores DERM GWDB; and» Exploration bores QPED, CSIRO Pressure Plot, QDEX well completion reports. DERM GWDB yields data for shallow water bores:» Lower Eromanga and upper Galilee aquifers tapped in the east; and» Eromanga and surface aquifers in the west. QPED CSIRO and QDEX yield data for:» Permian age aquifers; and» Basement aquifers.

37 Baseline groundwater levels With the exception of the GAB monitoring bores comparatively few groundwater level observations have been on average two observations per bore Most historical deep water bores tap more than one formation Difficult to assign an aquifer or group of aquifers to a water bore Paucity of time series data - difficult to evaluate antecedent pumping / flow conditions Existing rural development (artesian / sub-artesian bores) adds further amplitude to natural variability some bores have long-term depletion as Eromanga Basin has not reached post-development equilibrium; Groundwater levels are dynamic in natural settings (temporal changes to recharge amplitudes > 10 m in NT and ~ 2 m in SE Qld) Many springs are fault related and hence are open to more than one formation Spot bore dips can be meaningless or misinterpreted.

38 Sub-artesian monitoring bore RN Betts Creek Beds NE on tenement GWEL Residual Rainfall Dec Nov Nov Nov

39 Sub-artesian monitoring bore RN 1043 Possibly Cadna-Owie / Hooray / Ronlow beds North on tenement GWEL Residual Rainfall /01/ /12/ /12/ /12/ /12/ /12/ /12/ /12/ /12/1979 8/12/1989 6/12/1999

40 Sub-artesian monitoring bore RN unknown East on tenement GWEL Residual Rainfall Jan Dec Dec Dec Dec Dec Dec Dec Dec Dec Dec

41 Groundwater level assessment in progress Tenement-by-tenement summary of the available groundwater level data Contour the following piezometric elevations:» Rolling Downs Group» Cadna-owie Formation / Hooray Sandstone aquifer systems» Warang Sandstone / Clematis Sandstone aquifer systems» Data points for Permian largely preclude preparation of piezometric surface (i.e. few bores tapping a range of formations) Analysis of DERM Great Artesian Basin intake beds data:» Tipping bucket rainfall data; and» Paired groundwater level monitoring data (if available).

42 Groundwater quality Data sources:» Water bores DERM GWDB; and» Exploration bores QPED, CSIRO Pressure Plot, QDEX, well completion reports.

43 Groundwater Quality Piper Plots Areas remote from intake beds Areas closer to intake beds

44 Groundwater quality piper plots Areas closer to intake beds Areas remote from intake beds

45 Groundwater quality assessment in progress Tenement-by-tenement summary of the available groundwater quality data Interpret the individual piper plots Identify groundwater quality data gaps

46 A possible approach to monitoring Monitoring groundwater levels in existing water bores:» Approach will bias the results towards the shallow, dominantly Eromanga Basin aquifer, expect in the east;» Data on bore construction and water use history are incomplete;» Bores often tap multiple aquifers; and» Deeper aquifers will be missed. Monitoring groundwater levels and aquifer pressures in exploration wells:» Approach will provide access to the deeper aquifers;» Aquifers stratigraphically closer the Permian Coal Measures will be monitored; and» Logistically difficult due to likely artesian pressures. Monitoring groundwater levels at dedicated wells:» Dedicated groundwater level monitoring wells will be required at some stage where existing water bores or converted exploration wells are absent.

47 Conclusions so far There are sufficient data available to:» Define the hydrogeology of the Eromanga and Galilee Basin sediments in the study area» Develop a baseline understanding of groundwater occurrence and depth to groundwater across the tenements of interest» Define the regions where the actively tapped aquifers occur in proximity to proposed CSG operations» Develop a groundwater quality baseline» Identify potential groundwater level monitoring locations and» Identify data gaps

48 Way forward We are still awaiting some data from DERM Once this data is to hand we will complete scoping report