Journal of the Korean Institute of Gas (한국가스학회지)

The Korean Institute of GAS (한국가스학회)
권호 표지
DOI QR코드

DOI QR Code

Development of Production Performance Forecasting Model Considering Pressure Dependent Permeability at Coalbed Methane Reservoir

석탄층 메탄가스전에서 압력 의존 투과도를 고려한 생산거동 예측 모델 개발

  • Kim, Sangho (Dept. of Energy and Mineral Resources Engineering, Dong-A University) ;
  • Kwon, Sunil (Dept. of Energy and Mineral Resources Engineering, Dong-A University)
  • 김상호 (동아대학교 에너지자원공학과) ;
  • 권순일 (동아대학교 에너지자원공학과)
  • Received : 2019.03.05
  • Accepted : 2019.05.30
  • Published : 2019.06.29
Download PDF
⟨ Previous Next ⟩

Abstract

In this study, a model was developed for estimating deliverability considering the pressure dependent permeability and predicting production profile with Material Balance Equation(MBE) for Coalbed Methane(CBM) fields. The estimated deliverability was compared with the conventional deliverability based on CBM well testing data with coefficient of determination($R^2$). As a result, the former was 0.76 and the latter was 0.69. It was confirmed that the deliverability which consider the pressure dependent permeability is more adoptable when representing the productivity of CBM fields. Through this process, in order to calculate pressure dependent permeability when well testing data exist, a method to infer reservoir pressure within the radius of investigation was proposed. The production profile of 31 gas wells was predicted for 15 years, using the estimated deliverability and the MBE. After that, the results was compared with simulation results of the literature. The simulation results did not account the pressure dependent permeability and the developed model results considered that. As the applied field permeability rised 1.17 times, field production rate was increased approximately 15% than the literature results. According to other researches, the permeability of CBM fields can be rise 6 ~ 25 times. For these cases, the production profiles may have significant difference with conventional gas fields.

본 연구에서는 석탄층 메탄가스전에서의 영향반경 내 저류층 압력에 따라 변화하는 투과도를 고려한 저류층 생산성을 산출하고 그 저류층의 생산특성을 반영한 물질평형법을 사용하여 향후 생산거동을 예측하는 모델을 개발 하였다. 석탄층 메탄가스전을 대상으로 개발한 방법과 전통적인 방법의 저류층 생산성을 유정시험 측정치를 기준으로 비교하였다. 그 결과, 전자의 경우 결정계수($R^2$)가 약 0.76, 후자의 경우 0.69이었다. 이를 통해 석탄층 메탄가스전의 생산성을 대표할 때, 영향반경 내 저류층 압력과 압력 의존 투과도를 고려한 저류층 생산성이 더 적합함을 확인하였다. 이 과정을 통해 유정시험 측정치가 존재할 때, 압력 의존 투과도를 계산하기 위한 영향반경 내 저류층 압력을 산정하는 방법을 제안하였다. 산출한 저류층 생산성과 물질평형법을 이용하여 31개 가스정의 향후 15년간의 생산거동을 예측하여 압력 의존투과도를 고려하지 않은 문헌의 시뮬레이션 결과와 비교하였다. 적용된 현장의 압력 의존 투과도는 최대 1.17배 상승하여 각 가스정당 일일 생산량이 문헌의 결과 대비, 최대 약 15% 증가하는 결과가 도출되었다. 문헌들에 따르면, 석탄층 메탄가스전의 투과도는 저류층 압력에 따라 6~25배 증가하기도 한다. 그 경우, 생산거동은 전통적인 가스 전과 큰 차이가 나타날 것으로 사료된다.

Keywords

References

  1. Shin, H.D., Lee, G.S., Lee, D.S., Jang, I.S. and Park, C.H., Unconventional Resources Engineering, CIR, Seoul, Republic of Korea, (2015)
  2. Seidle, J.P., "Long-term gas deliverability of a dewatered coalbed", Journal of Petroleum Technology, 45(06), 564-569, (1993) https://doi.org/10.2118/21488-PA
  3. Schlumberger, Coalbed Methane: Clean Energy for the World, U.S.A, 4-13, (2009)
  4. AGR, 2018.12.05., www.agr.com/snackbox/blog/gas-production-from-coal-bed-methane
  5. Palmer, I., and Mansoori, J., "How Permeability Depends on Stress and Pore Pressure in Coalbeds: A New Model", SPE Reservoir Evaluation & Engineering, 1(06), 539-544, (1998) https://doi.org/10.2118/52607-PA
  6. Shi, J.Q. and Durucan, S., "Drawdown induced changes in permeability of coalbeds: a new interpretation of the reservoir response to primary recovery", Transport in porous media, 56(1), 1-16, (2004) https://doi.org/10.1023/B:TIPM.0000018398.19928.5a
  7. Shi, J.Q. and Durucan, S.,"Exponential growth in San Juan Basin Fruitland coalbed permeability with reservoir drawdown: model match and new insights", SPE Reservoir Evaluation & Engineering, 13(06), 914-925, (2010) https://doi.org/10.2118/123206-PA
  8. Thungsuntonkhun, W. and Engler, T.W., "Well Deliverability of Undersaturated Coalbed Reservoir", SPE Rocky Mountain Petroleum Technology Conference, Keystone, Colorado, 21-23 May, 7-11, (2001)
  9. Feng, Q. and Shi, H. and Zhang, X. and Du, P. and Zhang, J., "New Inflow Performance Relationship for Coalbed Methane Wells", SPE/EAGE European Unconventional Resources Conference and Exhibition, Vienna, Austria, 20-22 March, 1-11, (2012)
  10. Kwon, S.I,, Kwon, O,G., Sung,. W.M., Shin, H.D., Lee, G.S. and Lee, J.H., Petroleum Production Engineering, Gumibook, Seoul, (2014)
  11. Lee, W.J., and Wattenbarger, R.A., Gas Reservoir Engineering, SPE, Texas, (1996)
  12. Fekete, 2018.12.05., http://www.fekete.com/SAN/WebHelp/FeketeHarmony/Harmony_WebHelp/Content/HTML_Files/Reference_Material/General_Concepts/CBM_Properties.htm
  13. Seidle, J.P., Jeansonne, M.W. and Erickson, D.J., "Application of matchstick geometry to stress dependent permeability in coals", SPE Rocky Mountain Regional Meeting, Casper, Wyoming, 18-21 May, 433-444, (1992)
  14. Seidle, J., Fundamentals of COALBED METHANE Reservoir Engineering, PennWell, Oklahoma, (2011)