Coal Seam Gas (Coal Bed Methane) and Associated Gas
The complexity of coal seams and their reservoir behaviour is self evident. The extraction of coal and gas requires multi-disciplined engineering skills and expertise.
Sigra excels at optimisation of exploration and appraisal programmes for the development of coal and gas resources and the design of their extraction.
Our approach is tailored to the nature of the geology and to meet our Client’s requirements and budget. This process may involve commencement of production drilling or typically, a detailed testing regime to understand the reservoir prior to any attempt at production.
Generally, the less permeable the reservoir the more complex the completion system will be. To minimise completion costs, a greater effort has to be expended in determining the reservoir characteristics before embarking on production trials.
Sigra has the expertise, experience and equipment to determine the characteristics of lower permeability reservoirs and provide the analysis for production. This includes testing for directional permeability and determination of how the permeability will change with production.
Conventional wisdom of undertaking a detailed exploration programme, followed by pilot trials, may not be the most economical way to develop the resource.An approach particularly to the more simple and permeable reservoirs may be to move directly into production drilling combined with field measurement to gain the detailed knowledge of the reservoir during production.
Sigra can design an integrated process through the use of pressure transient testing between wells, augmented by measurement of gas content from core or by the company’s Gas Content Without Coring system to obtain the detailed information for characterisation of the reservoir during production. The analysis of all data is then used to determine the strategy to maximise the profitability of gas recovery.
Sigra can design a suitable production programme once a reasonable understanding of the reservoir has been arrived at. This may involve vertical or directional drilling, with varied completions ranging from under reaming to hydraulic fracturing, to suit the reservoir and economics of the project.
Sigra can supply some specialist production equipment of its own and where required has the ability to design and develop specialist components.
Sigra has the technology and software to remotely gather data from producing and monitoring wells with automated download. This data is essential for optimisation of production strategies.
Sigra’s foundation is in coal mining. Over the past 19 years all aspects of coal mining, from exploration to total underground mine design have been completed. Sigra’s service has expanded to cover all consulting and testing work relating to coal, gas, groundwater, rock mechanics and drilling.
Sigra is noted for its ability to innovate to find solutions to mining problems. This level of innovation extends from total mining systems down to rock bolt design. It has designed large underground mines to work in deep gassy multi seam environments. It has also designed sluiced hydraulic longwall mining systems to operate in steep narrow seams at a fraction of the cost of any other mining method. These represent several innovations specifically developed for particular coal deposits so as to make mining economically possible.
Sigra has been even more innovative in its specialist areas. It has a range of techniques and systems to determine the gas related properties of coals for the prediction, and avoidance of problems of outburst, high gas makes from cut coal at the face, from solid coal or from the goaf.
In the area of rock mechanics Sigra has developed its own in situ stress measurement tool (IST) by overcoring, which enables overcore stress measurements to be made at up to 2000 m depth. Using this tool, augmented by borehole breakout and seismic data, Sigra has also developed regional stress models. The basis of these is frequently the concept of tectonic strain. Using these initial stress models, Sigra can undertake geomechancial modelling of the effects of underground mining
Civil Geotechnical Design
Sigra’s experience encompasses the geomechanics discipline for all civil engineering design. This includes slope stability, excavations, foundations, tunnelling and cavern design.
Sigra has rock mechanics, groundwater and drilling design capabilities, and has used these in providing solutions for civil engineering. Examples of this are in the design of slope remediation works, rock anchoring for deep basements, and piling systems.
Sigra’s capabilities come to the fore when the project becomes increasingly intractable and requires solutions beyond the norm. Sigra is prepared to innovate to produce designs that are appropriate for the engineering challenges.
Sigra has the theoretical, field staff, design and monitoring capability to undertake major groundwater investigation work. This work may lead to groundwater production, dewatering for mining, or the determination of water production into coal seam gas reservoirs.
Sigra has taken projects from initial desk based studies, which have involved a geological and geophysical data review, to field measurement. The results of this are the determination of the prime engineering parameters such as permeability, storage and recharge and to use this information to arrive at a groundwater production, well design or a proposal for dewatering well field.
Sigra can supply the monitoring equipment and a total data acquisition service for local or remote sites.