Characterising the application of horizontal wells and indirect hydraulic fracturing for improved coal seam gas drainage

Johnson, Raymond L.; Cheong, Sharon Kah Heng; Farley, Andrew

doi:10.1071/aj20122

Cited by 5 publications

References 3 publications

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Co-application of micro-proppant with horizontal well, multi-stage hydraulic fracturing treatments to improve productivity in the Permian coal measures, Bowen Basin, Australia

et al. 2022

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Coal permeability is the key discriminator in well completion selection in coal wells. Low productivity is often attributed to compartmentalisation and pressure-dependent permeability (PDP) effects. Often, vertical well hydraulic fracturing is used to enhance productivity from lower-permeability coals, however, several authors have noted that coal fracture treatments can generate a large unpropped area of stimulated reservoir volume (SRV) that is generated from natural fracture activation and pressure-dependent leakoff. The result of this study confirms previous studies (using radial, cartesian, and enhanced SRV analytic models) that graded particle or micro-proppant injections in conjunction with hydraulic fracture treatments can be a means to enhance coal productivity in PDP-affected or low-permeability coals. In this work, data from the Bowen Basin will be used to investigate the implementation and benefits of micro-proppants in conjunction with horizontal well, multi-stage, hydraulic fracture treatments. The calibrated model will be based on a Bowen Basin case incorporating petrophysical, diagnostic fracture injection test (DFIT), hydraulic fracture, and can utilise production data to constrain modelling parameters. To better understand and provide guidance on co-application of horizontal, multi-stage hydraulic fracturing in conjunction with micro-proppant injections, a range of factors will be evaluated in this model including initial permeability, permeability anisotropy, fracture half-length, area and conductivity of the enhanced region between fractures, lateral length, and the number of fractures. This model will demonstrate the effectiveness, economic benefits, and optimal number of fracturing stages based on the reservoir parameters.

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Co-application of micro-proppant with horizontal well, multi-stage hydraulic fracturing treatments to improve productivity in the Permian coal measures, Bowen Basin, Australia

et al. 2022

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Don’t forget your keys when trying to unlock the productivity of low-permeability coals

Johnson

2024

Aust. Energ. Prod. J.

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Low-permeability coal seam gas (CSG) wells have been the subject of laboratory research and modelling studies over the past decade, particularly focusing on the pressure-dependent permeability (PDP) behaviour of coals. These research efforts have progressed diagnostic methods to identify and quantify PDP and provide practical technologies to counter these effects. Firstly, machine learning methods based on drilling and historical well-test data can provide insight into the range of coal permeability during drilling. Next, the process of history-matching the after-closure pressures from a diagnostic fracture injection test (DFIT), using reservoir simulators, can determine best-fit values for fracture compressibility, a key parameter for reservoir models. Finally, these data, along with DFIT reservoir pressure and permeability data, can inform the decision-making process regarding the most applicable completion strategy and aid developmental planning. For areas where vertical or surface-to-inseam (SIS) wells have been unsuccessful, new hydraulic fracturing technologies have been developed to enhance the stimulated reservoir volume (SRV) in coals, using horizontal wells with multi-stage hydraulic fracturing in excess of 20 stages. Recent laboratory and modelling of micro-proppants has extended prior laboratory and modelling studies and provided insight into proppant transport, embedment, and screen-out behaviour. These well stimulation technologies can be co-applied in new or existing CSG fields and are suitable for areas where overlapping tenements limit conventional, steel-based completion strategies. In conclusion, this paper will bring the key findings of these studies together in a cohesive framework and provide the workflows to implement these technologies for better productivity in low-permeability coals.

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Overflush and Hydraulic Fracturing: Playing Poker with Your Completion

Rylance¹

2023

SPE Journal

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Summary Since the inception of hydraulic fracturing, the industry has wrestled with the concept of over-/underflushing and has always pitched this as a binary philosophy, attempting to determine/define whether this is either a fundamentally good or a bad approach. This schism simply grew with the extensive development of unconventionals; the use of overflush being an inherent and fundamental requirement for an effective and economic unconventional completion sequence. This paper will demonstrate that the true answer, as any engineer would expect, is that a detailed assessment is what is required on a case-by-case basis. The paper will describe and reference several fracturing case histories in both the conventional and unconventional environments where the application of an overflush, an underflush, or an engineered approach has been assessed or applied. Rather than taking an easy headline grabbing route to perpetuate the myth that the process is a major paradigm or simply either a good or a bad thing, this paper will discuss some of the key aspects that impact the suitability of one approach over another and how engineering the implementation can lead to a broader range of applicability/suitability for the most economically effective outcome. This includes an appreciation of the production/economic profile and exposure to risk, which are hugely different in, say, an ultradeep-water five well offshore development vs. a field development with some 100s to 1,000s of wells in a lower-cost onshore environment. The paper will describe and demonstrate some of the fundamental variables that need to be considered, attempting to elaborate on a few of the key parameters that can influence the effective outcome. The paper will also indicate that there are several different scenarios whereby any form of overflush can result in a detrimental impact on the production rate and estimated ultimate recovery (EUR) and that these must be fully appreciated. Subtleties, related to reservoir characteristics and fracture geometry, should be examined and appreciated. Additional aspects such as how production, drawdown, and pore pressure will be managed can also have an impact. All these considerations, and more, will be discussed, described, and referenced. While there is no doubt that the overflush debate will continue unabated, the intent of this paper is to reduce the damage (or uncertainty), one way or the other, that will result. It is an attempt, at a minimum, to ensure that the debate becomes solely a technical one related to the approaches to be taken rather than a black and white one of right or wrong. Ultimately, the paper will advise, and inform, that the approach should be fully considered, engineered in detail and tailored to each, and every application and that as a result is no longer simply considered a binary question.

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Characterising the application of horizontal wells and indirect hydraulic fracturing for improved coal seam gas drainage

Cited by 5 publications

References 3 publications

Co-application of micro-proppant with horizontal well, multi-stage hydraulic fracturing treatments to improve productivity in the Permian coal measures, Bowen Basin, Australia

Co-application of micro-proppant with horizontal well, multi-stage hydraulic fracturing treatments to improve productivity in the Permian coal measures, Bowen Basin, Australia

Don’t forget your keys when trying to unlock the productivity of low-permeability coals

Overflush and Hydraulic Fracturing: Playing Poker with Your Completion

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