Economics for Enhanced Coalbed Methane (ECBM) and CO2 Sequestration with Horizontal Wells

2004 ◽  
Author(s):  
Sinisha A. Jikich ◽  
Grant S. Bromhal ◽  
W. Neal Sams ◽  
F. Burcu Gorucu ◽  
Ertekin Turgay ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Co2 Sequestration ◽  
Horizontal Wells ◽  
Enhanced Coalbed Methane

scholarly journals The Role of Coal Mechanical Characteristics on Reservoir Permeability Evolution and Its Effects on CO2 Sequestration and Enhanced Coalbed Methane Recovery

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-28
Author(s):  
Hao Han ◽  
Shun Liang ◽  
Yaowu Liang ◽  
Xuehai Fu ◽  
Junqiang Kang ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Co2 Sequestration ◽  
Mechanical Characteristics ◽  
Co2 Adsorption ◽  
Co2 Injection ◽  
Permeability Change ◽  
Coal Seams ◽  
Enhanced Coalbed Methane

Elastic modulus is an important parameter affecting the permeability change in the process of coalbed methane (CBM)/enhanced coalbed methane (ECBM) production, which will change with the variable gas content. Much research focuses on the constant value of elastic modulus; however, variable stiffness of coal during CO2 injection has been considered in this work. The coupled thermo-hydro-mechanical (THM) model is established and then validated by primary production data, as well as being applied in the prediction of CO2/N2-ECBM recovery. The results show that the harder coal seam is beneficial to primary production, while the softer coal seam results in greater CO2/N2-ECBM recovery and CO2 sequestration. N2 and CO2 mixture injection could be applied to balance early N2 breakthrough and pronounced matrix swelling induced by CO2 adsorption, and to prolong the process of effective CH4 recovery. Besides, reduction in stiffness of coal seam during CO2 injection would moderate the significant permeability loss induced by matrix swelling. With the increase of the weakening degree of coal seam stiffness, CO2 cumulative storage also shows an increasing trend. Neglecting the weakening effect of CO2 adsorption on coal seam stiffness could underestimate the injection capacity of CO2. Injection of hot CO2 could improve the permeability around injection well and then enhance CO2 cumulative storage and CBM recovery. Furthermore, compared with ECBM production, injection temperature is more favorable for CO2 storage, especially within hard coal seams. Care should be considered that significant permeability change is induced by mechanical characteristics alterations in deep burial coal seams in further study, especially for CO2-ECBM projects.

Thermo-hydro-mechanical-chemical couplings controlling CH4 production and CO2 sequestration in enhanced coalbed methane recovery

Energy ◽  
2019 ◽  
Vol 173 ◽  
pp. 1054-1077 ◽  
Author(s):  
Chaojun Fan ◽  
Derek Elsworth ◽  
Sheng Li ◽  
Lijun Zhou ◽  
Zhenhua Yang ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Co2 Sequestration ◽  
Methane Recovery ◽  
Enhanced Coalbed Methane Recovery ◽  
Ch4 Production ◽  
Enhanced Coalbed Methane

Simulating Carbon Dioxide Sequestration/ECBM Production in Coal Seams: Effects of Permeability Anisotropies and Other Coal Properties

2005 ◽  
Vol 8 (02) ◽  
pp. 156-163 ◽  
Author(s):  
Duane H. Smith ◽  
Grant Bromhal ◽  
W. Neal Sams ◽  
Sinisha Jikich ◽  
Turgay Ertekin
Keyword(s):  
Carbon Dioxide ◽  
Methane Production ◽  
Coalbed Methane ◽  
Co2 Sequestration ◽  
Horizontal Wells ◽  
Coal Seams ◽  
Injection Wells ◽  
Sequestration Potential ◽  
Production Wells ◽  
The Face

Summary Coalbed methane now accounts for a significant fraction of domestic natural-gas production. Injection of carbon dioxide (CO2) into coal seams is a promising technology for reducing anthropogenic greenhouse-gas emissions and increasing ultimate production of coalbed methane. Reservoir simulations are an inexpensive method for designing field projects and predicting optimal tradeoffs between maximum sequestration and maximum methane production. Optimum project design and operation are expected to depend on the anisotropy of the permeability along the face-cleat and butt-cleat directions, the spacing between cleats, and the sorption isotherms for methane and CO2. In this work, a dual-porosity coalbed-methane simulator is used to model primary and secondary production of methane from coal for a variety of coal properties and operational parameters. It is assumed that the face and butt cleats are perpendicular to each other, with horizontal wells parallel to one type of cleat and perpendicular to the other. The well pattern consists of four horizontal production wells that form a rectangle, with four shorter horizontal wells centered within the rectangle. In the limiting case of no permeability anisotropy, the central wells form a "plus" sign within the square of production wells. All wells are operated as producers of methane and water until a specified reservoir pressure is reached, after which the central wells are operated as injectors for CO2. Production of methane continues until the CO2 concentration in the produced gas is too high. The simulation results predict the optimum lengths of the injection wells along the face- and butt-cleat directions and show how these optimum lengths depend on the permeabilities in the two directions. If the cleat spacing is sufficiently small, and diffusion of the gas through the pores to the cleats is sufficiently rapid, instantaneous sorption may be assumed. Otherwise, the field performance depends on the diffusion-time constant that characterizes the rate of transfer between the cleats and the coal matrix. The pressures at which the injection wells are operated also affect the amounts of CO2 sequestered through the pressures and volumes of the sorption isotherms. Introduction and Background Increasing concentrations of greenhouse gases may be leading to changes in the Earth's climate. A rise in the globe's average temperature is expected, among other consequences. The main anthropogenic greenhouse gas is CO2. The concentration of CO2 in the atmosphere is increasing continuously; therefore, many countries have pledged to reduce, by 2010, the emissions of greenhouse gases up to 8% relative to levels pertaining to 1990. Consequently, CO2 must be captured and stored. Among storage options, the underground storage in depleted oil and gas reservoirs and unmineable coals is considered to have the most favorable economics. This option is also expected to have a low environmental impact. Several federal agencies have major programs for CO2sequestration. Unmineable coal seams are a very attractive potential storage medium forCO2. The injection of CO2 in coalbeds may be the most efficient option of all storage possibilities if, while CO2 is stored, the recovery of coalbed methane is improved. The process of displacing the remaining methane by CO2 after the primary production of methane is referred to as enhanced coalbed methane(ECBM). Carbon dioxide/ECBM technology and implementation were inspired by CO2solvent flooding, one of the most successful enhanced-oil-recovery methods in the U.S. and worldwide. The worldwide CO2-sequestration potential by use of ECBM has been estimated at 150 Gt of CO2. A relatively small but significant sequestration potential of 5 to 15 Gt may be profitable, generating net profits estimated at U.S. $15/t for the most favorable cases. A joint U.S. Dept. of Energy (DOE) and industry project has been initiated to study the reservoir mechanisms and field performance of CO2 sequestration in the world's first experimental (pure) CO2/ECBM recovery pilot, the Allison unit field, operated by Burlington Resources. Initially, the pilot was intended to test CO2/ECBM, but in time it evolved into a CO2-sequestration project. The pilot consists of four CO2-injection wells and nine methane-production wells, drilled on 320-acre spacing. The Allison unit CO2/ECBM shows that methane production has been enhanced by CO2 injection and that CO2 has been sequestered. In this project, vertical wells are used for both production and injection. However, it has been shown that horizontal wells can increaseCO2-injection rate and improve aerial sweep, which can lead to more-favorable flood economics. The sweep advantage is greatest in thin formations with wide well spacing, such as coal seams in the eastern United States. Consequently, the U.S. Dept. of Energy is cofunding a 7-year CO2-sequestration/ECBM project that uses horizontal injectors and producers. The well pattern used in the present study was suggested by the pattern chosen for that project.

A Neurosimulation Tool for Predicting Performance in Enhanced Coalbed Methane and CO2, Sequestration Projects

2005 ◽  
Author(s):  
Fatma Burcu Gorucu ◽  
Turgay Ertekin ◽  
Grant S. Bromhal ◽  
Duane H. Smith ◽  
W. Neal Sams ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Co2 Sequestration ◽  
Predicting Performance ◽  
Enhanced Coalbed Methane

Effects of Matrix Shrinkage and Swelling on the Economics of Enhanced-Coalbed-Methane Production and CO2 Sequestration in Coal

2007 ◽  
Vol 10 (04) ◽  
pp. 382-392 ◽  
Author(s):  
Fatma Burcu Gorucu ◽  
Sinisha A. Jikich ◽  
Grant S. Bromhal ◽  
W. Neal Sams ◽  
Turgay Ertekin ◽  
...  
Keyword(s):  
United States ◽  
Natural Gas ◽  
Methane Production ◽  
Coalbed Methane ◽  
Co2 Sequestration ◽  
The United States ◽  
Coal Seams ◽  
Enhanced Coalbed Methane ◽  
Coal Properties ◽  
Cleat Porosity

Summary Increases in carbon dioxide (CO2) levels in the atmosphere and their contributions to global climate change are a major concern. CO2 sequestration in unmineable coals may be a very attractive option, for economic as well as environmental reasons, if a combination of enhanced-coalbed-methane (ECBM) production and tax incentives becomes sufficiently favorable compared to the costs of capture, transport, and injection of CO2. Darcy flow through cleats is an important transport mechanism in coal. Cleat compression and permeability changes caused by gas sorption/desorption, changes of effective stress, and matrix swelling and shrinkage introduce a high level of complexity into the feasibility of a coal sequestration project. The economic effects of CO2-induced swelling on permeabilities and injectivities has received little (if any) detailed attention. CO2 and methane (CH4) have different swelling effects on coal. In this work, the Palmer-Mansoori model for coal shrinkage and permeability increases during primary methane production was rewritten to also account for coal swelling caused by CO2 sorption. The generalized model was added to a compositional, dual-porosity coalbed-methane reservoir simulator for primary (CBM) and ECBM production. A standard five-spot of vertical wells and representative coal properties for Appalachian coals was used (Rogers 1994). Simulations and sensitivity analyses were performed with the modified simulator for nine different parameters, including coal seam and operational parameters and economic criteria. The coal properties and operating parameters that were varied included Young's modulus, Poisson's ratio, cleat porosity, and injection pressure. The economic variables included CH4 price, CO2 cost, CO2 credit, water disposal cost, and interest rate. Net-present-value (NPV) analyses of the simulation results included profits resulting from CH4 production and potential incentives for sequestered CO2. This work shows that for some coal seams, the combination of compressibility, cleat porosity, and shrinkage/swelling of the coal may have a significant impact on project economics. Introduction In recent years, primary production of natural gas from coal seams has become an important source of energy in the United States. Proven CBM reserves have been estimated at 18.5 Tscf, representing 10% of the total natural-gas reserves in the United States. CBM production started in the early 1980s as a small, high-cost operation but reached 1.6 Tscf in 2002. This was more than 8% of the total US natural-gas production that year (Kuuskraa 2003). The production of CBM reservoirs begins with the pumping of significant volumes of water to lower reservoir pressure and to allow CH4desorption and flow (Stevens et al. 1998). The fraction of the original gas in place typically produced by primary depletion seems to be somewhat controversial. However, according to recent publications, recoveries are often between 20 and 60% of the original gas in place, so that considerable amounts of gas are left behind (Gale and Freund 2001; Stevens et al. 1999; Van Bergen et al. 2001).Because of this, and because of concerns about global warming caused by accumulations of CO2 in the atmosphere (National Energy Technology Laboratory 2003, 2004), new technologies for ECBM production based on the injection of carbon are being investigated in the US, Europe, China, and Japan (Coal-Seq Forum 2004, 2006). In the CO2-ECBM/sequestration process, injected CO2 flows through the cleats in the coal by Darcy flow, diffuses into the coal matrix, and is sorbed by it; CH4 diffuses from the matrix into the cleats, through which it flows to production wells (Sams et al. 2005). The injection of CO2 into coalbeds has many potential advantages: It sequesters CO2, it reduces the production time for CBM, and it increases reserves by improving the recovery of CBM. However, the improved CH4 recovery is accompanied by an increase in costs for CO2 supply, additional drilling, and well and surface equipment. Thus, CO2-ECBM and sequestration are accompanied not only by promised benefits but also by new technical challenges and financial risks.

CO2 sequestration in coals and enhanced coalbed methane recovery: New numerical approach

Fuel ◽  
2010 ◽  
Vol 89 (5) ◽  
pp. 1110-1118 ◽  
Author(s):  
Xiaorong Wei ◽  
Paul Massarotto ◽  
Geoff Wang ◽  
Victor Rudolph ◽  
Sue D. Golding
Keyword(s):  
Coalbed Methane ◽  
Co2 Sequestration ◽  
Numerical Approach ◽  
Methane Recovery ◽  
Enhanced Coalbed Methane Recovery ◽  
Enhanced Coalbed Methane
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