|
|
Coalbed Methane Production in the Midcontinent—A New Frontier |
| PTTC Home | Solutions From the Field |
Based on a workshop sponsored by PTTC's North Midcontinent Region on August 7, 2002 in Wichita, Kansas
Pennsylvanian-age bituminous coal deposits in eastern Kansas offer the best potential for exploration and development of coalbed methane resources in Kansas. Deep deposits of the Cherokee Group have the most exploitable coal seams. The federal tax credit for development of coalbed methane as an unconventional gas source has motivated development in Kansas.
The speakers at the Coalbed Methane workshop addressed a variety of exploration, operations and regulatory topics designed to increase understanding of how to find and develop coalbed methane resources in Kansas in a cost-effective manner.
CBM regulatory issues, Downhole water injection, Midcontinent coalbed methane, Progressive cavity pumps, Reservoir simulation, Well stimulation
Kansas Coal and Coalbed Methane - Exploration and Production
Larry Brady, Kansas Geological Survey, Lawrence, KS
Overview of Coal-gas Measurement: Field and Lab Procedures
Noel Waechter, Hampton, Waechter & Associates, LLC, Denver, CO
Coalbed Methane Production Operations in Kansas - A Regulatory Update
Diana Edmiston and Dave Williams, Kansas Corporation Commission/Conservation Division, Wichita, KS
Advances in Coalbed Methane Reservoir Simulation
Jim Erdle, Computer Modeling Group, LTD, Calgary, Alberta, Canada
Application and Operation of Progressive Cavity Pump Systems in CBM Wells
Jim Tupman, Petrolift Systems, Inc., Seminole, TX
Downhole Water Injection Methods for CBM Wells
David A. Hill, Chriscor Tools (KUDU Industries), Calgary, Alberta, Canada
Access to Marketers
David Englert, Jill Kittinger and Marc Garrison, Williams Gas Pipeline, Owensboro, KY
Completion Approach for Frontier Coalbed Methane Plays
David G. Hill and Steve Lambert, TICORA Geosciences, Inc. Arvada, CO
Total Management of CBM Operations from Prospect to Market
Dwayne McCune, KU TORP/ N. Midcontinent PTTC, Lawrence, KS
New technologies for identification of coal seams and criteria for evaluation of coals to determine those that are potential candidates for coalbed methane production have caused a significant increase in development in Kansas since the early 1990s. Technologies discussed include improved field and laboratory testing, the use of reservoir simulation, progressive cavity pump systems for lifting high volumes of fluid, downhole water injection, effective coalbed stimulation and improved management.
Middle and Upper Pennsylvanian-age bituminous coal deposits in eastern Kansas have produced over 300 million tons since the 1840s. Exploration and development of coalbed methane resources in the Rocky Mountains and northeastern Oklahoma prompted exploration in Kansas coalbeds starting in the late 1980s and early 1990s. The deep bituminous coals of the Cherokee Group have the best potential for coalbed methane development in Kansas. Criteria for identification of potential coalbed methane production are summarized in a stratigraphic review of Kansas coals. Thickness and depth of burial are key factors in successful coalbed methane exploration. Coalbed methane wells have increased from 230 in 1993 to over 500 in early 2002.
Coal gas production depends on reducing reservoir pressure through water production to initiate desorption of gas. Water-saturated coals may take a year to achieve peak production. Coals that start coal gas production from the beginning tend to peak earlier, but have a rapid decline. The ability to test coal gases to determine the quality and potential for production relies on tests to measure desorption of gases from coal core samples. Getting large, unbroken coal samples to the surface in the shortest time gives the most accurate results. Use of the correct core canister for specific circumstances and formations, and maintaining constant temperature and pressure logs is important to obtaining accurate estimates of gas content and future production. The advantages and disadvantages of wireline rigs, conventional cores and rotary sidewall cores were contrasted. Sidewall cores taken after wireline geophysical logging has been completed give the best potential for correlation results. Rotary sidewall cores are best for deeper wells where wireline cores are impractical or too expensive.
Kansas regulations for coalbed methane exploration and production govern drilling intent, permits for pits and pit closure, completion, gas well testing, site remediation and final reports. Specific regulations call for cementing and plugging deadlines, and allow commingling of coal gas production with application and approval by the Kansas Corporation Commission. All records from coalbed gas metering must be maintained for two years, and the first purchaser of the gas is responsible for reporting sales. Class II injection wells in Kansas follow the regulations set out by the Environmental Protection Agency, and all wells must pass mechanical integrity tests and have authorization prior to injection. Example forms and specific requirements were highlighted along with contact information for coal gas exploration and development concerns.
Data needed for reservoir simulation includes knowledge of coal structure, gas flow characteristics, CBM recovery mechanisms, properties of porosity systems present in the coal beds, understanding of gas diffusion from matrix to fracture, adsorption/desorption of CBM gas, and coal shrinking characteristics. Coalbed methane modeling must take into consideration the multi-component gases (CH4, CO2, N2) and diffusion modeling. The multi-component, multi-phase reservoir simulator, GEM (CMG's Equation of State Reservoir Simulator) is designed to take all of these parameters into account. Features include the ability for full-field simulation, display of results of 5-spot injection profiles, and GEM can provide an accurate image of coalbed methane resources from your data.
The advantages of progressive cavity pumps include high efficiency, low operating costs, low profile (leaves a small footprint), reduced capital costs, and minimal installation costs. Progressive cavity pumps (PCP) allow for constant flow production, will not gas lock, and are suitable for a wide range of production. PCPs are suitable for coalbed methane production because they are most applicable with high water production or variable water production where solids, sands, and coal fines are present. They also meet the requirements for low profiles necessary due to local conditions such as irrigation systems. Disadvantages may include problems with pump off or improper rotor sizing. Installation equipment and procedures are illustrated with a cost breakdown for equipment.
KUDU Industries, which was founded in 1989, holds over 15 patents on PCP systems used for downhole water injection. The operation of the PCP system is illustrated, demonstrating how the pump lifts a column of water and separates the gas flow to the surface via the tubing and casing annulus. Design criteria for KUDU's progressive cavity pump have improved the intake and discharge areas to reduce the potential for erosion or plugging as well as providing high volume lift capability. Success of PCP installation is directly dependent on the quality of the disposal zone. Fracs or acid jobs may be required to achieve disposal injectivity with the downhole injection PCP system. Systems are designed to reduce the high cost of water handling, which is highly significant in coalbed methane operations in Kansas.
Confidentiality of data and evaluation of customers CBM resources and pipeline requirements are important issues in marketing and pipeline management. The provisions of a standard confidentiality agreement include; who has the rights to evaluation materials, the use of these materials, disclosure to necessary parties, return or destruction of evaluation materials and records retention. Other specifications include the length of the contract (normally 2 years), and sections on enforcement and signature clauses. Sample forms were provided and discussed for Evaluation Materials.
A balanced approach to coalbed methane production from an idea or concept stage, through field work, testing, pilot wells to development wells is advocated for successful coalbed methane development. Completion processes include consideration of multiple steps in drilling, cementing, flow capacity, formation access, stimulation and production.
There are three approaches to a frontier completion: a thorough approach emphasizing high quality datasets to evaluate the reservoir; a demonstration approach to finding short cuts to producing by drilling wells to see if they will flow; and a balanced approach by collecting data of a specific reservoir and its production mechanisms. A first step to successful CBM well completion is understanding the geological setting, including coal distribution, number and thickness of coal seams, distance between seams and water zones, knowledge of the rock types, and permeability studies.
The objectives to stimulation of coalbeds are to bypass wellbore formation damage zones, effectively connect natural fractures in the coal system, accelerate dewatering to increase gas desorption, and to widely distribute near wellbore pressure drop to reduce fines production. Hydraulic fracturing creates variable, complex, multiple, horizontal and subparallel fractures and combinations of fractures in coalbeds. Keys to successful stimulation and development are to start simple, identify the problems and solve each before moving to the next stage. Be aware that what works best in one play may not be best in another. Use your understanding of the reservoir to make decisions.
The data required for management includes drilling and completion reports; geological reports; core data (descriptions, canister tests, sorption isotherm, proximate analysis, gas analysis); logs (density, GR-N/caliper); and production data (gas, water, static flow levels, injection tests). Reservoir data for coalbeds includes net pay thickness, pressure, permeability, temperature and all related tests and analysis. The more data and sources of information available for total management, the higher the potential for successful development and marketing of coalbed methane gas.
Diana Edmiston
Dave Williams
Kansas Corporation Commission
Conservation Division, Finney State Office Building
130 S. Market, Room 2078
Wichita, KS 67202-3802
Phone: 316-337-6200 Fax: 316-337-6211
Email: dedmiston@kcc.state.ks.us
Email: dwilliams@kcc.state.ks.us
Larry Brady
Kansas Geological Survey
1930 Constant Avenue
Lawrence, KS 66047-3724
Phone: 785-864-2159 Fax: 785-864-5317
Email: lbrady@kgs.ku.edu
David Hill
TICORA Geosciences, Inc.
19000 West Highway 72, Ste. 100
Arvada, CO 80007
Phone: 720-898-8200 Fax: 720-898-8222
Email: dave-hill@gti-ticora.com
David Englert
Jill Kittinger
Marc Garrison
Williams Gas Pipeline
3800 Frederica St.
Owensboro, KY 42303
Phone: 270-688-6914 Fax: 270-688-6320
Email: david.m.englert@williams.com
Email: jill.l.kittinger@williams.com
Email: marc.g.garrison@williams.com
Jim Erdle
Computer Modeling Group, LTD
3150, 3553-31 St. NW
Calgary, Alberta, Canada T2L 2K7
Phone: 403-531-1300 Fax: 403-289-8502
Email: cmgl@cmgl.ca
Dwayne McCune
PTTC North Midcontinent Region
1930 Constant Avenue
Lawrence, KS 66047-3724
Phone: 785-864-7398 Fax: 785-864-7399
Email: dmccune@cpe.engr.ukans.edu
Noel Waechter
Hampton, Waechter & Associates, LLC
1645 Court Place, Ste. 300
Denver, CO 80202-4507
Phone: 303-825-7140 Fax: 720-528-7680
Email: nbwaechter@qwest.net
Jim Tupman
PetroLift Systems, Inc.
P.O. Box 116
Seminole, TX 79360
Phone: 915-758-5260 Fax: 915-758-5259
Email: jtupman@nwol.net
David A. Hill
Chriscor Downhole Tools
(KUDU Industries)
9112-40 Street SE
Calgary, Alberta, Canada T2C 2P3
Phone: 403-203-1279 Fax: 403-279-2192
Email: chriscor@chriscortools.com
For information on PTTC's North Midcontinent Region and it's activities contact:
Rodney R. Reynolds, Project Manager, Kansas University Energy Research Center
1930 Constant Ave., Lawrence, KS. 66047-3726
Phone: 785-864-7398, Fax: 785-864-7399, Email: rreynolds@ku.edu
Disclaimer: No specific application of products or services is endorsed by PTTC. Reasonable steps are taken to ensure the reliability of sources for information that PTTC disseminates; individuals and institutions are solely responsible for the consequences of its use.
The not-for-profit Petroleum Technology Transfer Council is funded primarily by the US Department of Energy’s Office of Fossil Energy, with additional funding from universities, state geological surveys, several state governments, and industry donations.
Petroleum Technology Transfer Council, 2916 West T. C. Jester, Suite 103, Houston, TX 77018
Toll-free 1-888-THE-PTTC; Fax 713-688-0935; E-mail hq@pttc.org;
web www.pttc.org
| PTTC Home | Solutions From the Field |
|
We encourage your comments, please send us email at: hq@pttc.org or use our Feedback Form. Copyright © 2004 Petroleum Technology Transfer Council |