Value Optimisation of Future Coal Seam Gas Field Developments Using Horizontal Wells

Xu, Nicola; Weatherstone, Petrina; Alam, Naureen; Lin, Xuejun

doi:10.2118/176904-ms

Cited by 2 publications

(1 citation statement)

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“…To enhance production in low permeability reservoirs the coal seams may be under-reamed to create a cavity or fracture stimulated or drilled horizontally, perpendicular to natural fractures if they exist. Reductions in drilling costs and increases in production in the Bowen Basin's Spring Gully field, located approximately 80 km north of Roma in Queensland, have been documented by Xu et al [52]. The wells were previously developed with vertical wells and a cavitation completion or sometimes by hydraulic fracture stimulation.…”

Section: Accepted Manuscriptmentioning

confidence: 97%

An overview of the coal seam gas developments in Queensland

Towler

Firouzi

Underschultz

et al. 2016

Journal of Natural Gas Science and Engineering

156

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The demand for natural gas in Queensland, Australia has historically been supplied from conventional reservoirs. However, depletion in conventional sources has led producers to turn to extensive supplies in Queensland's coal resources. These coal seam gas (CSG) developments not only represent new supplies for the domestic market in eastern Australia, they are also the first time that CSG (aka coal bed methane or CBM) has been liquefied to serve the expanding world LNG market. In order to make this development occur, considerable infrastructure had to be installed, with field developments still on-going. This AUD$60 billion investment precipitated a major overhaul of state regulations to provide not only a safe and clean operating environment, but also to allay the concerns of certain stakeholders.The gas is primarily produced from thin high permeability coals in the Jurassic-age Walloon Coal Measures in the Surat Basin and from several relatively thick Permian-age coal seams in the Bowen Basin, of which the Baralaba Coal Measures and the Bandanna formation are the most important. There are numerous technical challenges with this production, such as fines production from the inter-burden clays, which can form a thick paste that is difficult to pump. Salt extraction by reverse osmosis, from associated water produced to depressurise the coal seams and enable the flow of gas, allows for the beneficial use of the water. Technical challenges also include mathematical modelling of the countercurrent two-phase flow (gas and water) in the well annuli because conventional models in simulators only handle co-current two-phase flow in the well-bores. Also, the subject of ongoing investigations is decommissioning of the large number of shallow wells over the next few decades in a safe and cost effective manner, with compressed bentonite being a promising option for well plugging.As with any major commercial development, in addition to the technical challenges there have been social challenges as well. These include interaction and coexistence of extensive surface operations with an established agricultural sector, interactions between gas M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPTproduction and ground water aquifers in water-stressed areas, and the cumulative social and economic impacts of 3 large projects on a rural area.Ultimately, the State of Queensland expects to produce more than 1,800 BCF/annum, of which about 1,400 BCF/annum will be exported as LNG. Depending on the demand and well productivity, up to 1,000 CSG wells may be drilled per year for the next thirty years. A review of CSG resources, development, and challenges is presented in this paper to provide context for a stream of research findings that are emerging on the Queensland CSG experience. M A N U S C R I P TA C C E P T E D ACCEPTED MANUSCRIPT construction and development phase to a production and operational phase it is timely to review how it occurred, the challenges overcome and the prospects for the future. The lessons learned and discussed...

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Section: Accepted Manuscriptmentioning

confidence: 97%

An overview of the coal seam gas developments in Queensland

Towler

Firouzi

Underschultz

et al. 2016

Journal of Natural Gas Science and Engineering

156

View full text Add to dashboard Cite

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Seamless in seam – new geosteering technology delivered challenging coal seam gas project with success

Nick Kholgh¹,

Mackinlay²,

Garrard³

et al. 2022

APPEA J.

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A recent coal seam gas (CSG) appraisal project posed several challenges. The target reserve area had limited seismic data available and yet had complex structure with several faults of variable orientations and throws between 2 and 25 m. Dual-lateral extended-reach drilling (ERD) wells needed to be drilled in order to access this reserve, with a 1000 m in-seam section for each lateral planned to maximise production. Conventional technologies for CSG projects included motor bottom hole assembly with a boundary mapping tool for geosteering in the coal seams. However, for drilling ERD wells in this unknown area, these methods were insufficient to deliver success, due to the limited mapping capabilities and drilling efficiencies. Recently there has been significant development on the directional resistivity-based mapping tool, on both the measurements and processing. The operator adopted a new mapping-while-drilling technology which has the first-in-industry tool with axial, tilted and transverse antennas integrated in one module. This new technology can provide high-resolution multilayer mapping with doubled depth of investigation, even when drilling out of the coal seam. The results from utilising this new tool, together with a rotary steerable system for directional control, were very encouraging. The new multilayer mapping-while-drilling tool mapped both the top and base of the coal seam throughout horizontal sections in-seam. In addition, it detected the coal seams during landing and after fault-crossing from up to 4 m true vertical depth away, enabling the team to navigate through complex fault zones confidently, and to deliver the project with success.

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Value Optimisation of Future Coal Seam Gas Field Developments Using Horizontal Wells

Cited by 2 publications

References 0 publications

An overview of the coal seam gas developments in Queensland

An overview of the coal seam gas developments in Queensland

Seamless in seam – new geosteering technology delivered challenging coal seam gas project with success

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