scholarly journals The prediction of structural fractures in coal seams of the Kuba coalfield, China: an application for coalbed methane (CBM) recovery development

2019 ◽  
Vol 72 (Special issue) ◽  
pp. 57-69
Author(s):  
Zhou Zhang ◽  
Min Zhoua ◽  
Yun-Xing Cao ◽  
Bao-An Xian ◽  
Di Gao
Keyword(s):  
Coalbed Methane ◽  
Coal Seams

scholarly journals Environmental Risk Related to the Exploration and Exploitation of Coalbed Methane

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6537
Author(s):  
Barbara Uliasz-Misiak ◽  
Jacek Misiak ◽  
Joanna Lewandowska-Śmierzchalska ◽  
Rafał Matuła
Keyword(s):  
Coalbed Methane ◽  
Environmental Risks ◽  
Risk Category ◽  
Burial History ◽  
Exploration And Exploitation ◽  
Coal Seams ◽  
Mining Operations ◽  
Environmental Threats ◽  
And Migration ◽  
Coal Macerals

In coal seams, depending on the composition of coal macerals, rank of coal, burial history, and migration of thermogenic and/or biogenic gas. In one ton of coal 1 to 25 m3 of methane can be accumulated. Accumulation of this gas is included in unconventional deposits. Exploitation of methane from coal seams is carried out with wells from mining excavations (during mining operations), wells drilled to abandoned coal mines, and wells from the surface to unexploited coal seams. Due to the low permeability of the coal matrix, hydraulic fracturing is also commonly used. Operations related to exploration (drilling works) and exploitation of methane from coal seams were analyzed. The preliminary analysis of the environmental threats associated with the exploration and exploitation of coalbed methane has made it possible to identify types of risks that affect the environment in various ways. The environmental risks were estimated as the product of the probability weightings of adverse events occurring and weightings of consequences. Drilling operations and coalbed methane (CBM) exploitation leads to environmental risks, for which the risk category falls within the controlled and accepted range.

Research on Nano-Emulsion Relieving Coal Seam Water Block Damage

2021 ◽  
Author(s):  
Wei Sun ◽  
LongHao Zhao ◽  
Qian Wang ◽  
Yanchi Liu ◽  
Weiping Zhu ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coalbed Methane ◽  
Mixed Micelles ◽  
Polymer Adsorption ◽  
Coal Seams ◽  
Fracturing Fluid ◽  
Flow Experiment ◽  
Nano Emulsion ◽  
Water Block ◽  
Lock In

Abstract Hydraulic fracturing is the most effective reservoirstimulation techniques in the coalbed methane. However, the polymer in the fracturing fluid has a strong effect on the surface of the coal, causing the water lock damage as high as 70% to 90%. It is important to develop an efficient method for releasing coal seam water lock. In this paper, adsorption experiment, SEM, particle size experiment, core flow experiment, wettability and surface tension experiment are used to study the cause of coal seam water lock damage during fracturing and the effect of nano-emulsion on releasing water lock damage in coal seams. Experimental results show that after coal fracturing, the adsorption amount of polymer on the surface of coal is 14.81 mg/g. The large amount of hydrophilic polymer adsorption causes the pore radius of the coal to narrow. And the surface wettability changes from weak hydrophilic to strong hydrophilic, which increase the water lock damage. Compared with conventional slick water, fracturing fluid, the composite of nano-emulsion and fracturing fluid forms mixed micelles, which reduces the polymer adsorption capacity from 14.81 mg/g to 7.42 mg/g. After scanning by electron microscope, it is observed that the surface roughness of the rock sample is restored; The size of the nano-emulsion is about 10nm, and the very small volume can act deep in the pores of the coal seam; After using nano-emulsion, the gas/water interfacial tension is reduced by 45.1mN/m, and the wettability of coal is improved from hydrophilic to neutral, which reduces the capillary pressure in the pores of the coal and reduces the breakthrough pressure of coalbed methane by 11.1KPa; The water lock release rate is as high as 53.09%. The Nano-emulsion is an ideal choice to remove water lock damage.

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.

scholarly journals Optimization methods of production layer combination for coalbed methane development in multi-coal seams

2018 ◽  
Vol 45 (2) ◽  
pp. 312-320 ◽  
Author(s):  
Zhaobiao YANG ◽  
Zhengguang ZHANG ◽  
Yong QIN ◽  
Congcong WU ◽  
Tongsheng YI ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Optimization Methods ◽  
Coal Seams ◽  
Production Layer

COAL SEAM GAS—PETROLEUM OR MINERAL

1997 ◽  
Vol 37 (1) ◽  
pp. 589
Author(s):  
D.J. Gately
Keyword(s):  
Private Sector ◽  
Coal Seam ◽  
Coalbed Methane ◽  
Resource Development ◽  
Coal Seams ◽  
Coal Seam Gas ◽  
Commercial Use ◽  
Private Sector Investment ◽  
History Of ◽  
Policy Shift

1996 was a watershed year for gas exploration in Queensland: the increasing private sector investment in the search for and commercial use of methane gas from coal seams received legislative endorsement. Coal seam gas (CSG), also known as coalbed methane or CBM, was officially designated as petroleum, with exploration for and production of CSG to be administered under the Petroleum Act.The paper traces the history of exploration for CSG in Queensland since 1976, culminating in a policy shift in 1996. In Queensland there is now potential for overlapping titles and competitive resource development.

scholarly journals CBM Resources Estimations for the Development of Coal Mine Methane in the Asturian Central Basin, Spain

Proceedings ◽  
2018 ◽  
Vol 2 (23) ◽  
pp. 1404
Author(s):  
Pablo Cienfuegos-Suárez ◽  
Efrén García-Ordiales ◽  
Diego Alonso-Fernández ◽  
Jorge Enrique Soto-Yen
Keyword(s):  
Coal Mine ◽  
Coalbed Methane ◽  
Technological Development ◽  
Gas Content ◽  
Central Basin ◽  
Economic Interest ◽  
Coal Seams ◽  
Coal Basin ◽  
Coal Mine Methane ◽  
Made In

New technological development and a best knowledge of the basin allow to have justified expectation to find coalbed methane reserves. Measurements of gas content in unexploited coal seams are made in order to estimate the CBM could revive the economic interest of the Asturian Central Coal Basin (ACCB). According to first estimations based on the studies accomplished, the minimum resources of coalbed methane in the whole of the Asturian Central Coal Basin are in the order of 25,000 Mm3 and the gas content of the coal seams range from 6 m3 to 14 m3/t. The introduction should briefly place the study in a broad context and define the purpose of the work and its significance.

scholarly journals Study on geological controls and enrichment models of coalbed methane in the Wuwei Basin in eastern North Qilian, northwestern China

2018 ◽  
Vol 37 (1) ◽  
pp. 429-452
Author(s):  
Wenchao Shen ◽  
Longyi Shao ◽  
Wenguang Tian ◽  
Gang Chen ◽  
Fei Chen ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Sedimentary Environment ◽  
Controlling Factors ◽  
Gas Content ◽  
Methane Formation ◽  
Coal Seams ◽  
Mineral Contents ◽  
The North ◽  
Taiyuan Formation ◽  
Lagoon Environment

The Wuwei Basin is located in the Gansu Corridor, which has abundant coalbed methane resources of 2.75 × 1011 m3. However, a low degree of coalbed methane exploration exists, and only a few wells have been drilled in local regions due to insufficient understanding of coalbed methane enrichment and its main controlling factors. This study analyzed the controlling factors of coalbed methane enrichment, including coal reservoir characteristics, hydrogeological conditions, and the original sedimentary environment of the coal-bearing strata. The results showed that the main coal seams were developed in the Taiyuan Formation, and were mostly concentrated in the Yingpan Sag in the south and the Ermahu Sag in the north of the study area. The macrolithotype of the coals in this basin was mainly semi-bright coal with a medium to high rank. Coal macerals were mainly vitrinite, ranging between 65.1% and 91.6% (averaged 81.70%), followed by liptinite, ranging between 1.9% and 29.5% (averaged 8.82%), and inertinite, ranging between 0.2% and 16.5% (averaged 3.66%). Mineral contents varied from 2.5% to 15.1% (averaged 6.16%). The macrolithotype and microlithotype of the Taiyuan Formation coals were favorable for coalbed methane formation. Through comparative analysis of moisture content, ash yield, gas content, and coal-forming sedimentary environments, it was found that the coal formed in the lagoon environment had a higher gas content and lower ash yield than that of the coal formed in the tidal flat environment. The high contents of total dissolved solids in aquifers around coal seams (1.75–16.70 g/L) reflected the closed hydrodynamic environment and were favorable for the preservation of coalbed methane in the Yingpan Sag. Considering various controlling factors (i.e., structure, sedimentation and hydrogeology), three coalbed methane enrichment models were proposed. The model of coalbed methane enrichment in the synclinorium was the most favorable for the enrichment of coalbed methane in the Yingpan Sag.

scholarly journals Decreasing Coalbed Methane Formation Damage Using Microfoamed Drilling Fluid Stabilized by Silica Nanoparticles

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Jihua Cai ◽  
Sui Gu ◽  
Fawen Wang ◽  
Xianyu Yang ◽  
Ye Yue ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Performance Appraisal ◽  
Coalbed Methane ◽  
Gas Permeability ◽  
Foam Stability ◽  
Drilling Fluid ◽  
Formation Damage ◽  
Methane Formation ◽  
Coal Seams ◽  
20 Nm

Coalbed methane (CBM) reservoirs in China are featured in remarkable nanosized pores below 200 nm, acknowledged natural cleats, and tectonic fractures. This paper discussed the possibility that a clay free microfoamed drilling fluid could be stabilized by silica nanoparticles (CFMDF-NP) so as to avoid formation damage of CBM drilling. In accordance with the experimental results of foaming capacity and foam stability test, basic drilling fluid performance appraisal, micromorphology observation, swelling test, and gas permeability test, the mechanism of the CFMDF-NP was discussed in this paper. The results indicated that, with 10–20 nm nano-SiO2, the foaming volume of traditional foamed drilling fluid could be improved by up to 50% and an increased half-life period by up to 200%. Chemically treated nano-SiO2dispersions functioned as a foam stabilizer and a foaming agent as well. The CFMDF-NP had controllable density (0.7~1 g/cm3) and excellent rheological and sealing properties, which could satisfy the drilling requirements of the low pressure coal seams. With 5–8 mm slicing on the contaminated side of coal cores, the contaminated zone could be removed and the recovery rate of gas permeability could reach up to 70%. The CFMDF-NP laid good technical foundation to decrease formation damage of CBM reservoir.

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