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Methods for simultaneously evaluating reserve and permeability of undersaturated coalbed methane reservoirs using production data during the dewatering stage
- Source :
- Petroleum Science. 17:1067-1086
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- In this work, a flowing material balance equation (FMBE) is established for undersaturated coalbed methane (CBM) reservoirs, which considers immobile free gas expansion effect at the dewatering stage. Based on the established FMBE, five straight-line methods are proposed to determine the control area, initial water reserve, initial free gas reserve, initial adsorbed gas reserve, original gas in place, as well as permeability at the same time. Subsequently, the proposed FMBE methods for undersaturated CBM reservoirs are validated against a reservoir simulation software with and without considering free gas expansion. Finally, the proposed methods are applied in a field case when considering free gas expansion effect. Validation cases show that the straight-line relationships for the proposed five FMBE methods are excellent, and good agreements are obtained among the actual reserves and permeabilities and those evaluated by the proposed five FMBE methods, indicating the proposed five FMBE methods are effective and rational for CBM reservoirs. Results show that a small amount of free gas will result in a great deviation in reserve evaluation; hence, the immobile free gas expansion effect should be considered when establishing the material balance equation of undersaturated CBM reservoirs at the dewatering stage.
- Subjects :
- Free gas
Coalbed methane
Petroleum engineering
Material balance equation
Energy Engineering and Power Technology
Geology
02 engineering and technology
010502 geochemistry & geophysics
Geotechnical Engineering and Engineering Geology
01 natural sciences
Dewatering
Reservoir simulation
Permeability (earth sciences)
Geophysics
Fuel Technology
020401 chemical engineering
Geochemistry and Petrology
Environmental science
Economic Geology
0204 chemical engineering
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 19958226 and 16725107
- Volume :
- 17
- Database :
- OpenAIRE
- Journal :
- Petroleum Science
- Accession number :
- edsair.doi...........6b7a86434c3c81e35f4412cf919f4001
- Full Text :
- https://doi.org/10.1007/s12182-019-00410-3