The Analysis and Theory Research on the Factor of Multiple Fractures During Hydraulic Fracturing of CBM Wells

Hong-chao, Wei; Li, Lianggang; Wu, Xiaoming; Hu, Yule

doi:10.1016/j.proeps.2011.09.088

Cited by 10 publications

(4 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[1][2][3] Moreover, to prevent and control coal mine methane disasters, many technologies have been developed to enhance methane extraction, including large-diameter intensive drilling, hydraulic fracturing, hydraulic slotting, and hydraulic punching. [4][5][6][7][8][9][10][11] Although some progress has been made in this area, these methods are still facing low methane extraction efficiency or methane production. The production of CBM typically features three distinct stages: desorption, diffusion, and percolation.…”

Section: Introductionmentioning

confidence: 99%

“…Global recoverable CBM reserves are estimated at 49 × 10 12 m 3 , which accounts for 21.7% of the world's unconventional methane resources 1–3 . Moreover, to prevent and control coal mine methane disasters, many technologies have been developed to enhance methane extraction, including large‐diameter intensive drilling, hydraulic fracturing, hydraulic slotting, and hydraulic punching 4–11 . Although some progress has been made in this area, these methods are still facing low methane extraction efficiency or methane production.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Experimental study on improving coalbed methane extraction by chemical treatment using acetic acid or ammonium persulfate

Wang

Chen

2022

Energy Science & Engineering

View full text Add to dashboard Cite

Ad‐/desorption and diffusion processes are the key factors controlling methane production from coal. The experiments used samples from methane‐producing coal seams with different contents of carbonate mineral and different ranks. Acid treatment using 1.0 mol/L acetic acid (CH3COOH) and oxidant treatment using 1.0 mol/L ammonium persulfate ((NH4)2S2O8) were conducted on these coal samples to observe the changes in surface functional groups that act as primary sorption sites and pore structure that determines diffusivity by Fourier transform infrared spectrometer, in situ scanning electron microscopy (SEM) imaging and energy dispersive spectroscopy. The results showed that the acidizing‐related mass loss of coal samples is in the range of 3.78%–7.57% due to the complete dissolution of pore‐ and fracture‐filling carbonate minerals. For the coal samples after oxidizing treatment, dissolution evidence can be observed in both carbonate minerals and organic matter, with a mass loss ranging from 2.01% to 3.0%. Acidizing or oxidizing induced dissolution can destroy aliphatic functional groups and the cross‐linked structure of coal, resulting in a decrease in methane adsorption capacity that is beneficial to methane desorption. More opened pores and interconnected fractures can be observed in SEM images due to the dissolution of carbonate minerals, suggesting an alteration of methane diffusion pathways in the coal matrix. Although only some of the carbonate minerals were dissolved following oxidant treatment, coal organic matter is partially oxidized and generates some dissolution pores, which provides more methane diffusion pathways in the coal matrix. Therefore, all the treated coal samples showed a reduction in methane adsorption capacity and an enhancement of desorption capacity and diffusivity. This result suggests that chemical treatment in coal seams using acetic acid or oxidant has the potential to improve coalbed methane extraction.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Experimental study on improving coalbed methane extraction by chemical treatment using acetic acid or ammonium persulfate

Wang

Chen

2022

Energy Science & Engineering

View full text Add to dashboard Cite

show abstract

“…(Fischer et al 1994;Economides 2006;Civan 2010;Fang and Khaksar 2011;Zhang et al 2012;Ziarani and Aguilera 2012;Hou et al 2013;Pan et al 2014;Chen et al 2015). Meanwhile, previous stages of hydraulic fracturing would affect later stages of fracturing (Xu 2009;Wei et al 2011;Chuprakov et al 2011;Wang et al 2014b).…”

Section: Introductionmentioning

confidence: 99%

Stress redistribution in multi-stage hydraulic fracturing of horizontal wells in shales

Zeng

Zhang

2015

Pet. Sci.

View full text Add to dashboard Cite

Multi-stage hydraulic fracturing of horizontal wells is the main stimulation method in recovering gas from tight shale gas reservoirs, and stage spacing determination is one of the key issues in fracturing design. The initiation and propagation of hydraulic fractures will cause stress redistribution and may activate natural fractures in the reservoir. Due to the limitation of the analytical method in calculation of induced stresses, we propose a numerical method, which incorporates the interaction of hydraulic fractures and the wellbore, and analyzes the stress distribution in the reservoir under different stage spacing. Simulation results indicate the following: (1) The induced stress was overestimated from the analytical method because it did not take into account the interaction between hydraulic fractures and the horizontal wellbore. (2) The hydraulic fracture had a considerable effect on the redistribution of stresses in the direction of the horizontal wellbore in the reservoir. The stress in the direction perpendicular to the horizontal wellbore after hydraulic fracturing had a minor change compared with the original in situ stress. (3) Stress interferences among fractures were greatly connected with the stage spacing and the distance from the wellbore. When the fracture length was 200 m, and the stage spacing was 50 m, the stress redistribution due to stage fracturing may divert the original stress pattern, which might activate natural fractures so as to generate a complex fracture network.

show abstract

“…Much of the conventional oil and gas technology translates to some instances, CBM operations require entirely different crustal stresses and wellbore geometric configurations all contribute to differences in wellbore stress conditions, thus leading to various fracture initiation scenarios (Jeffrey et al, 2009;Zhang and Chen, 2009;Zhou et al, 2010;Chuprakov et al, 2011;Hou et al, 2013). The problem of hydraulic fracturing in coal seams has been widely investigated both experimentally (Khodaverdian et al, 1991;Penny et al, 1991;Fang and Khaksar, 2011) and numerically (Mavko et al, 1986;Ramurthy and Lyons, 2007;Wei et al, 2011). Many tests in the field (Diamond and Oyler, 1987;Palmer and Sparks, 1991;Jeffrey and Weber, 1994;Jeffrey et al, 1998) and in the laboratory (Abass et al, 1990; have shown that the geometry of hydraulic fractures that grow in the coal seam is very complex, and attributed that to the unique characteristics of coal seams, such as brittleness, high Poisson's ratio, low elastic modulus and the very development of the cleat system.…”

Section: Introductionmentioning

confidence: 99%

The impact of cleats on hydraulic fracture initiation and propagation in coal seams

Fan

Zhang

Cui³

2014

Pet. Sci.

View full text Add to dashboard Cite

Cleats are systematic, natural fractures in coal seams. They account for most of the on the success of hydraulic fracturing stimulation. Laboratory hydraulic fracturing experiments were conducted on coal blocks under true tri-axial stress to simulate fracturing stimulation of coal seams. section of a wellbore. The impact of cleats on initiation and propagation of hydraulic fractures in coal seams is discussed. Three types of hydraulic fracture initiation and propagation pattern were observed in this study: 1) The hydraulic fracture initiated and then grew along the cleat. 2) The hydraulic fracture initiated along a butt cleat or a fracture (natural or induced by drilling) oriented roughly in the minimum horizontal stress direction, then turned to propagate along the first face cleat that it encountered or gradually turned towards the maximum horizontal stress direction. 3) The hydraulic fracture initiated perpendicular to the minimum stress and, when it encountered a face cleat, tended to propagate along the cleats if the extension direction does not deviate greatly (<20° as determined in this paper) from the maximum horizontal stress direction. When a coal seam is hydraulically fractured, the resulting fracture network is controlled by the combined effect of several factors: cleats determine the initiation and extension path of the fracture, the in-situ stress state dominates the main direction of the fracture zone and bedding planes impede fracture height growth.

show abstract

The Analysis and Theory Research on the Factor of Multiple Fractures During Hydraulic Fracturing of CBM Wells

Cited by 10 publications

References 2 publications

Experimental study on improving coalbed methane extraction by chemical treatment using acetic acid or ammonium persulfate

Experimental study on improving coalbed methane extraction by chemical treatment using acetic acid or ammonium persulfate

Stress redistribution in multi-stage hydraulic fracturing of horizontal wells in shales

The impact of cleats on hydraulic fracture initiation and propagation in coal seams

Contact Info

Product

Resources

About