U.S. Department of the Interior Alaska Rural Energy Project Results from the Coalbed Methane Exploration and Testing Project Wainwright, Alaska 2007-2008 2008 Art Clark U.S. Geological Survey, Denver, CO Bob Fisk Bureau of Land Management, Anchorage, AK
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.
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 -
Wainwright 2007-2008 2008 CBM Exploratory Drilling and Testing Project A Cooperative Effort Between BLM USGS Arctic Slope Regional Corporation North Slope Borough Olgoonik Corporation
In August 2006, the Alaska Rural Energy Project barged equipment to Wainwright to conduct drilling and testing operations in 2007. 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.
DOI Drilling Rig Wainwright, Alaska June, 2007
Continuous coring operations
Collecting coal core for desorption
Desorbing coal samples coal core desorbing at surface
Collecting geophysical data coal coal
Collecting water samples
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
Depth v Raw SCF Gas/Ton Coal: Final 0 200 Raw SCF/Ton 0 20 40 60 80 100 120 140 160 180 200 220 240 Dep th (ft) 400 600 800 1000 1200 1400 1600 1800 2000 Depth v Raw SCF/Ton Approximate depth of permafrost 3 samples from 1250 ft coal bed avg ~155 scf/ton
200 180 As-Received Langmuir Isotherm Graph Coal core sample W-21 Depth = 1245.9 ft Reservoir temperature = 35 o F Desorbed + residual gas = 176 scf/ton Storage Capacity, scf/ton 160 140 120 100 80 60 40 20 Desorbed gas = 159 scf/ton Reservoir Pressure = 539 psi As-Received Langmuir Fit 95% Confidence Interval 0 0 100 200 300 400 500 600 700 800 900 1,000 Pressure, psia Reservoir pressure = hydrostatic pressure =.433 psi/ft
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.
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
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.
June 2008: Transporting truck-mounted drilling rig to Wainwright
Drilling Operations Wainwright, AK June 2008
Final 2008 Wainwright production test well pattern 100 ft W-OC4 W-OCP W-OC1 W-OC2 W-OC3 2008 Production Well 2008 Monitor Well 2007 Temperature Well
Submersible pump control panel and gas/water separation tank
Production head assembly
Drilling rig and production test equipment Wainwright, AK; August 2008
Comparison of gas and aquifer discharges 4 Gas Flow, SL/min Aquifer Q, L/min (/1.5) Flow, in L/min or SL/min 2 0 0 1000 2000 3000 4000 5000 6000 7000 Time in minutes since start of test
Produced methane gas being flared from water/gas separation tank
Production well W-OCPW OCP-08 with protective cover
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
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.
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.
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.