Coalbed Methane Pilots--Timing, Design, and Analysis
- Randahl D. Roadifer (ConocoPhillips Alaska) | Thomas R. Moore (EXCO-North Coast Energy)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- October 2009
- Document Type
- Journal Paper
- 772 - 782
- 2009. Society of Petroleum Engineers
- 3 in the last 30 days
- 2,181 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
Four distinct sequential phases form a recommended process for coalbed-methane (CBM)-prospect assessment: initial screening, reconnaissance, pilot testing, and final appraisal. Stepping through these four phases provides a program of progressively ramping work and cost, while creating a series of discrete decision points at which analysis of results and risks can be assessed. While discussing each of these phases in some degree, this paper focuses on the third, the critically important pilot-testing phase.
This phased CBM-prospect assessment process allows us to
- Gain local knowledge early at low cost
- Progressively acquire and compile appropriate data to assess the geological situation and reservoir conditions systematically
- Identify and attempt to fill the most important knowledge gaps that represent the greatest uncertainties and risks to the prospect
- Increasingly understand the distributions of key parameters that control reserves, deliverability, and value
- Stage expenditures and provide multiple decision points through the process
- Ultimately, produce a project with very low development risk
In the CBM-prospect assessment process, the pilot test serves the same function as a conventional exploration well. If it proves successful, then the prospect can be considered a discovery and can be appraised for development. By drilling, completing, and producing a cluster of wells in a CBM pilot test, short of proceeding directly to a partial development, we are able to locally dewater and depressurize the coal seam to be tested and, thereby, desorb and deliver measurable volumes of gas. If correctly implemented, the pilot test allows us to assess the local variability of key reservoir parameters, collect the information necessary to simulate the reservoir's producibility, and, thereby, estimate potential project reserves to a reasonable degree of accuracy.
This paper contains roughly 30 specific recommendations and the fundamental rationale behind each recommendation to help ensure that a CBM pilot will fulfill its primary objectives of (1) demonstrating whether the subject coal reservoir will desorb and produce consequential gas and (2) gathering the data critical to evaluate and risk the prospect at the next--often most critical--decision point. Importantly, these objectives must be met in a timely manner. To do this, the specifications for the pilot are often not those that will be used for an optimized well or field-development pattern in terms of costs or production. This is intentional. The goals of piloting are different from the goals of development. So, the recommended designs are different. The pilot design recommendations focus on collecting superior data that will quantify key parameters for interpretation and simulation of the reservoir, retaining flexibility in the face of the level of uncertainty remaining after the reconnaissance phase, and arriving at a definitive answer on the coal reservoir's viability in an acceptable time frame.
Detailed data-analysis methods for CBM are not discussed here--these are well covered in the literature. Rather, we focus on the importance, use, and potential pitfalls of data collected at the various phases of the assessment process. Examples are used to highlight the purpose and importance of various aspects of the data gathering and analysis. A general history-matching process--valid at the pilot-stage analysis and beyond--is presented as a guide.
|File Size||362 KB||Number of Pages||11|
Bastian, P.A., Wirth, O.F.R., Wang, L., and Voneiff, G.W. 2005. Assessment and Development of the DryHorseshoe Canyon CBM Play in Canada. Paper SPE 96899 presented at the SPEAnnual Technical Conference and Exhibition, Dallas, 9-12 October. doi:10.2118/96899-MS.
Blauch, M.E., Weida, D., Mullen, M., and McDaniel, B.W. 2002. Matching Technical Solutions to theLifecycle Phase is the Key to Developing a CBM Prospect. Paper SPE 75684presented at the SPE Gas Technology Symposium, Calgary, 30 April-2 May. doi:10.2118/75684-MS.
Clarkson, C.R. and McGovern, J.M. 2005. Optimization ofCoalbed-Methane-Reservoir Exploration and Development Strategies ThroughIntegration of Simulation and Economics. SPE Res Eval & Eng8 (6): 502-519. SPE-88843-PA. doi: 10.2118/88843-PA.
Green, T.W., Wolfe, S.R., and Tedesco, S.A. 2003. Pilot Tests In the Illinois AndWestern Interior Basins To Determine Commercial Productivity From PennsylvanianAged Coals. Paper SPE 84430 presented at the SPE Annual TechnicalConference and Exhibition, Denver, 5-8 October. doi: 10.2118/84430-MS.
Haskett, W.J. and Brown, P.J. 2005. Evaluation of Unconventional ResourcePlays. Paper SPE 96879 presented at the SPE Annual Technical Conference andExhibition, Dallas, 9-12 October. doi: 10.2118/96879-MS.
Leach, P.E., Brown, P.J., and Haskett, W.J. 2007. Value-of-Information Applications inUnconventional Resource Plays. Paper SPE 108175 presented at theHydrocarbon Economics and Evaluation Symposium, Dallas, 1-3 April. doi:10.2118/108175-MS.
Mavor, M.J., Gunter, W.D., and Robinson, J.R. 2004. Alberta Multiwell Micro-Pilot Testingfor CBM Properties, Enhanced Methane Recovery and CO2 Storage Potential.Paper SPE 90256 presented at the SPE Annual Technical Conference andExhibition, Houston, 26-29 September. doi: 10.2118/90256-MS.
Moore, T.R., Farnan, R.A., Crabtree, B.J., Raterman, K.T., and Roadifer,R.D. 2003. Phased Coalbed Methane Prospect Assessment Process. Posterpresentation given at the AAPC Annual Convention, Salt Lake City, Utah, 11-14May.
Nuccio, V. 2000. Coal-Bed Methane: Potential and Concerns. USGS Fact SheetFS-123-00, Energy Resources Surveys Program, U.S. Geological Survey, http://pubs.usgs.gov/factsheet/fs123-00/.
Puri, R., Voltz, R., and Duhrkopf, D. 1995. A Micro-Pilot Approach toCoalbed Methane Reservoir Assessment. Proc., Intergas 95, University ofAlabama/Tuscaloosa, Alabama, 15-19 May, Paper 9556, 265-274.
Rice, D. 1997. Coalbed Methane--An Untapped Energy Resource and anEnvironmental Concern. USGS Fact Sheet FS-019-97, Energy Resources SurveysProgram, U.S. Geological Survey, http://energy.usgs.gov/factsheets/Coalbed/coalmeth.html.
Roadifer, R.D. 2004a. Coalbed Methane Parametric Study: What's ReallyImportant to Production and When? Paper SPE 101513 presented as an SPEDistinguished Lecture during the 2003-2004 season.
Roadifer, R.D. 2004b. San Juan Basin History Match and Infill DrillingStudy. Invited presentation at the Montana Tech SPE 9th Annual TechnicalSymposium, Butte, Montana, USA, 22-23 April.
Roadifer, R.D., Farnan, R.A., Crabtree, B.J., Raterman, K.T., and Moore,T.R. 2003a. History Matching (Reservoir Parameter Estimation) for CoalbedMethane Reservoirs via Monte Carlo Simulation. Presented at the 2003International Coalbed Methane Symposium, Tuscaloosa, Alabama, USA, 5-9 May.
Roadifer, R.D., Moore, T.R., Raterman, K.T., Farnan, R.A., and Crabtree,B.J. 2003b. Coalbed MethaneParametric Study: What's Really Important to Production and When? Paper SPE84425 presented at the SPE Annual Technical Conference and Exhibition, Denver,5-8 October. doi: 10.2118/84425-MS.
Roadifer, R.D., Yeh, N.S., and Jones, J.R. 1995. Accurate Well Condition EstimatesUnder Multiphase Flow Conditions. Paper SPE 30579 presented at the SPEAnnual Technical Conference and Exhibition, Dallas, 22-25 October. doi:10.2118/30579-MS.
Rodvelt, G.D. and Oestreich, R.G. 2005. Case History: First CommercialIllinois Coal Bed Methane Project Commences Through a Structured ResourceEvaluation Plan. Paper SPE 97720 presented at the SPE Eastern RegionalMeeting, Morgantown, West Virginia, USA, 14-16 September. doi:10.2118/97720-MS.
Weida, S.D., Lambert, S.W., and Boyer, C.M. II. 2005. Challenging the Traditional CoalbedMethane Exploration and Evaluation Model. Paper SPE 98069 presented at theSPE Eastern Regional Meeting, Morgantown, West Virginia, USA, 14-16 September.doi: 10.2118/98069-MS.