The impact of the coal macrolithotype on reservoir productivity, hydraulic fracture initiation and propagation

Yulong Liu, Hao Xu, Dazhen Tang, Jonathan P. Mathews, Yuyang Zhai, Wei Hou, Song Li, Shu Tao, Xianyue Xiong, Wei Wang

Research output: Contribution to journalArticle

Abstract

Macrolithotypes control the pore-fracture distribution heterogeneity in coal, which impacts stimulation via hydrofracturing and coalbed methane production in the reservoir. Here, the aspects of coalbed methane production that are impacted by macrolithotype were determined from production data from 56 wells in the Hancheng Block, China. The macrolithotype contribution had a significant influence on the well productivity, with dull lithotype-rich (dull and semi-dull coal) coal having significantly lower productivity than wells with bright lithotype-rich (bright and semi-bright coal) coal. The main reason for this difference is that macrolithotypes impart a fracture distribution, which further impacts the hydrofracture stimulation and subsequent coalbed methane production. Here, the hydraulic fracture was evaluated using the appropriate mechanical behavior for each macrolithotype with PFC2D software, and the impact of the macrolithotype on hydraulic fracture initiation and propagation, which are controlled by stress and mechanical properties, was investigated systematically. The result showed that the hydraulic fracture propagation types are controlled by the pre-existing natural fractures. Furthermore, due to the well-developed natural fracture network, the hydraulic fractures in bright coal were mainly composed of the opening, steering propagation, and compound types, forming a lattice-like fracture network. Dull coal is denser, and its hydraulic fractures are characterized as an isolated fracture distribution. The conclusions were verified through monitoring of hydraulic fracture by the microseism wells which show that the fracture in the bright coal is more likely to match the “complex fracture network” description, and the “simple” case when the dull coal is fractured. Meanwhile, the hydraulic fractures mainly open at a shallow depth, but with the increase in depth, the hydraulic fractures are dominated by the crossing type. If the hydraulic fractures are the opening type, only at a higher liquid pressure can the natural fractures in dull coal be initiated. Thus, the difference between hydraulic fractures in bright and dull coal lead to different flow paths and ultimately result in a variation of coalbed methane production. Therefore, during coalbed methane output, a bright coal reservoir will have more potential than a dull coal reservoir, which provides a scientific base for coalbed methane exploration and development.

Original languageEnglish (US)
Pages (from-to)471-483
Number of pages13
JournalFuel
DOIs
StatePublished - Mar 1 2019

Fingerprint

Coal
Crack propagation
Productivity
Hydraulics

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Organic Chemistry

Cite this

Liu, Yulong ; Xu, Hao ; Tang, Dazhen ; Mathews, Jonathan P. ; Zhai, Yuyang ; Hou, Wei ; Li, Song ; Tao, Shu ; Xiong, Xianyue ; Wang, Wei. / The impact of the coal macrolithotype on reservoir productivity, hydraulic fracture initiation and propagation. In: Fuel. 2019 ; pp. 471-483.
@article{1f72ac6e93fb4df7ac6b107754616de7,
title = "The impact of the coal macrolithotype on reservoir productivity, hydraulic fracture initiation and propagation",
abstract = "Macrolithotypes control the pore-fracture distribution heterogeneity in coal, which impacts stimulation via hydrofracturing and coalbed methane production in the reservoir. Here, the aspects of coalbed methane production that are impacted by macrolithotype were determined from production data from 56 wells in the Hancheng Block, China. The macrolithotype contribution had a significant influence on the well productivity, with dull lithotype-rich (dull and semi-dull coal) coal having significantly lower productivity than wells with bright lithotype-rich (bright and semi-bright coal) coal. The main reason for this difference is that macrolithotypes impart a fracture distribution, which further impacts the hydrofracture stimulation and subsequent coalbed methane production. Here, the hydraulic fracture was evaluated using the appropriate mechanical behavior for each macrolithotype with PFC2D software, and the impact of the macrolithotype on hydraulic fracture initiation and propagation, which are controlled by stress and mechanical properties, was investigated systematically. The result showed that the hydraulic fracture propagation types are controlled by the pre-existing natural fractures. Furthermore, due to the well-developed natural fracture network, the hydraulic fractures in bright coal were mainly composed of the opening, steering propagation, and compound types, forming a lattice-like fracture network. Dull coal is denser, and its hydraulic fractures are characterized as an isolated fracture distribution. The conclusions were verified through monitoring of hydraulic fracture by the microseism wells which show that the fracture in the bright coal is more likely to match the “complex fracture network” description, and the “simple” case when the dull coal is fractured. Meanwhile, the hydraulic fractures mainly open at a shallow depth, but with the increase in depth, the hydraulic fractures are dominated by the crossing type. If the hydraulic fractures are the opening type, only at a higher liquid pressure can the natural fractures in dull coal be initiated. Thus, the difference between hydraulic fractures in bright and dull coal lead to different flow paths and ultimately result in a variation of coalbed methane production. Therefore, during coalbed methane output, a bright coal reservoir will have more potential than a dull coal reservoir, which provides a scientific base for coalbed methane exploration and development.",
author = "Yulong Liu and Hao Xu and Dazhen Tang and Mathews, {Jonathan P.} and Yuyang Zhai and Wei Hou and Song Li and Shu Tao and Xianyue Xiong and Wei Wang",
year = "2019",
month = "3",
day = "1",
doi = "10.1016/j.fuel.2018.10.150",
language = "English (US)",
pages = "471--483",
journal = "Fuel",
issn = "0016-2361",
publisher = "Elsevier BV",

}

The impact of the coal macrolithotype on reservoir productivity, hydraulic fracture initiation and propagation. / Liu, Yulong; Xu, Hao; Tang, Dazhen; Mathews, Jonathan P.; Zhai, Yuyang; Hou, Wei; Li, Song; Tao, Shu; Xiong, Xianyue; Wang, Wei.

In: Fuel, 01.03.2019, p. 471-483.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The impact of the coal macrolithotype on reservoir productivity, hydraulic fracture initiation and propagation

AU - Liu, Yulong

AU - Xu, Hao

AU - Tang, Dazhen

AU - Mathews, Jonathan P.

AU - Zhai, Yuyang

AU - Hou, Wei

AU - Li, Song

AU - Tao, Shu

AU - Xiong, Xianyue

AU - Wang, Wei

PY - 2019/3/1

Y1 - 2019/3/1

N2 - Macrolithotypes control the pore-fracture distribution heterogeneity in coal, which impacts stimulation via hydrofracturing and coalbed methane production in the reservoir. Here, the aspects of coalbed methane production that are impacted by macrolithotype were determined from production data from 56 wells in the Hancheng Block, China. The macrolithotype contribution had a significant influence on the well productivity, with dull lithotype-rich (dull and semi-dull coal) coal having significantly lower productivity than wells with bright lithotype-rich (bright and semi-bright coal) coal. The main reason for this difference is that macrolithotypes impart a fracture distribution, which further impacts the hydrofracture stimulation and subsequent coalbed methane production. Here, the hydraulic fracture was evaluated using the appropriate mechanical behavior for each macrolithotype with PFC2D software, and the impact of the macrolithotype on hydraulic fracture initiation and propagation, which are controlled by stress and mechanical properties, was investigated systematically. The result showed that the hydraulic fracture propagation types are controlled by the pre-existing natural fractures. Furthermore, due to the well-developed natural fracture network, the hydraulic fractures in bright coal were mainly composed of the opening, steering propagation, and compound types, forming a lattice-like fracture network. Dull coal is denser, and its hydraulic fractures are characterized as an isolated fracture distribution. The conclusions were verified through monitoring of hydraulic fracture by the microseism wells which show that the fracture in the bright coal is more likely to match the “complex fracture network” description, and the “simple” case when the dull coal is fractured. Meanwhile, the hydraulic fractures mainly open at a shallow depth, but with the increase in depth, the hydraulic fractures are dominated by the crossing type. If the hydraulic fractures are the opening type, only at a higher liquid pressure can the natural fractures in dull coal be initiated. Thus, the difference between hydraulic fractures in bright and dull coal lead to different flow paths and ultimately result in a variation of coalbed methane production. Therefore, during coalbed methane output, a bright coal reservoir will have more potential than a dull coal reservoir, which provides a scientific base for coalbed methane exploration and development.

AB - Macrolithotypes control the pore-fracture distribution heterogeneity in coal, which impacts stimulation via hydrofracturing and coalbed methane production in the reservoir. Here, the aspects of coalbed methane production that are impacted by macrolithotype were determined from production data from 56 wells in the Hancheng Block, China. The macrolithotype contribution had a significant influence on the well productivity, with dull lithotype-rich (dull and semi-dull coal) coal having significantly lower productivity than wells with bright lithotype-rich (bright and semi-bright coal) coal. The main reason for this difference is that macrolithotypes impart a fracture distribution, which further impacts the hydrofracture stimulation and subsequent coalbed methane production. Here, the hydraulic fracture was evaluated using the appropriate mechanical behavior for each macrolithotype with PFC2D software, and the impact of the macrolithotype on hydraulic fracture initiation and propagation, which are controlled by stress and mechanical properties, was investigated systematically. The result showed that the hydraulic fracture propagation types are controlled by the pre-existing natural fractures. Furthermore, due to the well-developed natural fracture network, the hydraulic fractures in bright coal were mainly composed of the opening, steering propagation, and compound types, forming a lattice-like fracture network. Dull coal is denser, and its hydraulic fractures are characterized as an isolated fracture distribution. The conclusions were verified through monitoring of hydraulic fracture by the microseism wells which show that the fracture in the bright coal is more likely to match the “complex fracture network” description, and the “simple” case when the dull coal is fractured. Meanwhile, the hydraulic fractures mainly open at a shallow depth, but with the increase in depth, the hydraulic fractures are dominated by the crossing type. If the hydraulic fractures are the opening type, only at a higher liquid pressure can the natural fractures in dull coal be initiated. Thus, the difference between hydraulic fractures in bright and dull coal lead to different flow paths and ultimately result in a variation of coalbed methane production. Therefore, during coalbed methane output, a bright coal reservoir will have more potential than a dull coal reservoir, which provides a scientific base for coalbed methane exploration and development.

UR - http://www.scopus.com/inward/record.url?scp=85056471875&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85056471875&partnerID=8YFLogxK

U2 - 10.1016/j.fuel.2018.10.150

DO - 10.1016/j.fuel.2018.10.150

M3 - Article

SP - 471

EP - 483

JO - Fuel

JF - Fuel

SN - 0016-2361

ER -