U.S. Department of the Interior Alaska Rural Energy Project

Transcription

1 U.S. Department of the Interior Alaska Rural Energy Project Results from the Coalbed Methane Exploration and Testing Project Wainwright, Alaska Art Clark U.S. Geological Survey, Denver, CO Bob Fisk Bureau of Land Management, Anchorage, AK

2 The DOI Alaska Rural Energy Project is a collaborative effort between the BLM, USGS, state, local and private partners, designed to identify and assess shallow (<3000 ft) subsurface resources such as coalbed methane (CBM) and geothermal in the vicinity of rural Alaskan communities. In certain areas, these resources have the potential l to serve as local-use power alternatives to diesel fuel which currently must be transported, transferred, and stored at great expense to state and local government. Identifying and producing clean, locally- derived, economic energy resources would provide great benefit to the State, to rural communities, and to the citizens of Alaska.

3 Wainwright Point Lay Atqusuk Alaska rural energy base map showing select rural communities with some shallow subsurface resource potential Nome Kotzebue Galena McGrath Fort Yukon Bethel Chignik Unalaska Alaska Rural Energy Project Base Map not for distribution -

4 Wainwright CBM Exploratory Drilling and Testing Project A Cooperative Effort Between BLM USGS Arctic Slope Regional Corporation North Slope Borough Olgoonik Corporation

5 In August 2006, the Alaska Rural Energy Project barged equipment to Wainwright to conduct drilling and testing operations in The primary objectives of this effort were to determine: 1. Number, depth, and thickness of coal beds 2. Depth of coal in relation to the permafrost 3. Volume of gas contained within coal beds 4. Degree of gas saturation, i.e. drawdown required to produce gas from the coal 5. Coal bed permeability 6. Chemistry of coal bed waters Using these data, a determination could be made as to whether small-scale scale production testing would be warranted in 2008.

6 DOI Drilling Rig Wainwright, Alaska June, 2007

7 Continuous coring operations

8 Collecting coal core for desorption

9 Desorbing coal samples coal core desorbing at surface

10 Collecting geophysical data coal coal

11 Collecting water samples

12 Work accomplished during the 2007 Wainwright CBM drilling-testing effort 1613 ft well drilled with 95% core recovery Penetrated 70 net feet of coal in 24 beds > 1 ft thick Desorbed 25 coal cores for gas content Collected gas samples for chemical and isotopic analysis Collected permeability data and water samples for quality analysis from coal bed of primary interest Set long-term temperature monitor well

13 Depth v Raw SCF Gas/Ton Coal: Final Raw SCF/Ton Dep th (ft) Depth v Raw SCF/Ton Approximate depth of permafrost 3 samples from 1250 ft coal bed avg ~155 scf/ton

14 As-Received Langmuir Isotherm Graph Coal core sample W-21 Depth = ft Reservoir temperature = 35 o F Desorbed + residual gas = 176 scf/ton Storage Capacity, scf/ton Desorbed gas = 159 scf/ton Reservoir Pressure = 539 psi As-Received Langmuir Fit 95% Confidence Interval ,000 Pressure, psia Reservoir pressure = hydrostatic pressure =.433 psi/ft

15 Results from the 2007 Wainwright exploratory test drilling indicate that: 1. There is enough CBM contained within subpermafrost coal seams underlying Wainwright and vicinity to serve as an alternative energy source for the community. 2. Desorbed gas, as analyzed, is almost pure methane 3. Permafrost and subpermafrost coal beds appear to be saturated with respect to methane gas 4. Coal bed permeability might allow for the production of CBM without the need for extensive reservoir stimulation. 5. Coal bed water is relatively high in total dissolved solids and would likely need to be reinjected into deeper strata when produced.

16 After completing the 2007 drilling and testing activities Analyze Data - Desorption Data - Isotherm Data - Hydraulic Data - Water Chemistry Data - Geophysical Data Determine whether production testing is warranted YES NO Winterize equipment: Secure funding and transport larger truck-mounted rig to Wainwright to conduct production testing in 2008 Abandon well and transport exploratory equipment from Wainwright

17 2008 Wainwright Project Objectives 1. Drill delineation well to establish lateral continuity of coal beds and confirm gas content. 2. Drill to 2500 ft to search for deeper coal beds and sand bodies that might serve as produced-water reinjection zones. 3. To drill and install production and monitor well array in 1250 ft deep coal bed. 4. Conduct step-drawdown / production test to collect initial reservoir data and to establish techniques and procedures to be used in proposed 2009 long- term test.

18 June 2008: Transporting truck-mounted drilling rig to Wainwright

19 Drilling Operations Wainwright, AK June 2008

20 Final 2008 Wainwright production test well pattern 100 ft W-OC4 W-OCP W-OC1 W-OC2 W-OC Production Well 2008 Monitor Well 2007 Temperature Well

21 Submersible pump control panel and gas/water separation tank

22 Production head assembly

23 Drilling rig and production test equipment Wainwright, AK; August 2008

24 Comparison of gas and aquifer discharges 4 Gas Flow, SL/min Aquifer Q, L/min (/1.5) Flow, in L/min or SL/min Time in minutes since start of test

25 Produced methane gas being flared from water/gas separation tank

26 Production well W-OCPW OCP-08 with protective cover

27 Preliminary Results of 2008 Wainwright Drilling-Testing Effort 2450 ft well drilled and logged No significant (>2 ft) coal beds below 1250 ft All subsurface gas is associated with coal beds Mud-gas samples collected at 100 ft intervals: Analyses pending One production well and four monitor wells drilled, completed, and instrumented in 1250 ft deep coal bed Short-term term step-drawdown/production test conducted Methane gas produced throughout test Coal bed is saturated with methane gas ~½ mcf gas produced Average coal bed yield = ~1 gpm water Bed permeability = ~75mD Production and monitor wells winterized and available for longer 2009 production test

28 Summary I The 2008 Wainwright Production Test showed that methane gas can be produced from the subpermafrost coal bed located 1250 ft below land surface and that the bed is at, or near, full gas saturation. A longer production test will be required in 2009 to collect the data required to more fully define reservoir properties and evaluate production potential.

29 Summary II The Wainwright CBM project shows that exploration and test drilling to assess shallow subsurface energy resources can be successfully and economically conducted in remote Arctic locations using portable drilling equipment. Similar equipment and techniques can be used to conduct comparable studies in other frontier locations where little or no subsurface information is available.

30 Acknowledgments Thanks to the following organizations for their financial and logistical support throughout the Wainwright project: Arctic Slope Regional Corporation North Slope Borough Olgoonik Corporation Thanks to the citizens of Wainwright for the warmth and hospitality displayed to project personnel throughout the project. Special thanks to the USGS and BLM scientists, technicians, and drilling personnel whose dedication and hard work made a successful project possible.