Water-supply companies monitor the state of their pipe networks and ensure that the pipes are clean and free of inert loose deposits by flushing and pigging. Flushing involves forcing high speed water through the pipes so as to carry away particulates, pigging consists of forcing an object (the pig) through the pipe so as to push or wipe away the loose material. Both systems have drawbacks; the first tends to use very large volumes of water, and it may be impossible to get the required velocities in large-diameter pipes. The second requires purpose built launch and receive stations and may run the risk of damaging the pipe walls. This paper presents an innovative alternative to water flushing or conventional pigging for the potable-water-supply industry. This alternative uses a phase change material (ice-water slurry), which can be introduced into and removed from existing pipe networks with minimal alterations. The underlying concept is that when an ice slurry is propelled through pipes at modest speeds, the wall shear is two to four orders of magnitude higher than that which would have been achieved had water (only) been travelling in the pipe at the same speed. Thus, even with relatively low speeds, the 'ice pig' is able to achieve efficient cleaning and removal of loose materials. This technology has the advantage that the ice pig changes its shape to fit the containing topology, hence it is able to navigate bends, contraction/expansions and partly open vales, while cleaning the containment walls and transporting particulates. Lastly, the ice pig is guaranteed never to get stuck, as it will simply melt away, if left for sufficient time.The paper presents laboratory experimental data, qualitatively demonstrating the capability of the technique and quantitative data enabling engineers to scale and size the ice pig for full scale trials. Finally, preliminary work from full scale trails on live water trunk mains is briefly presented and discussed.

Summary In 2009, QGC (a BG Group company) began developing coal-seam-gas (CSG) feedstock for its new liquefied-natural-gas (LNG) plant and required a subsurface model and field-development plan to underpin the investment case for the project. Fundamental to the modeling process was acquiring appropriate data to calibrate subsurface models and enhance confidence in their predictive quality. As part of an integrated reservoir-surveillance strategy, specific pressure- and temperature-monitoring wells were required. This paper describes the successful laboratory and field implementation of an innovative completion technique that converts suspended coreholes into reservoir- and aquifer-monitoring wells. The coreholes are re-entered, and vibrating wire piezometers attached to capillary coiled tubing are positioned and cemented in place alongside selected reservoir intervals. The well is then “plugged and abandoned,” and the lease is remediated to leave only a small surface footprint for the data logger and telemetry. The cement is effectively impermeable to fluid movement, but possesses sufficient permeability to transmit reservoir pore pressure to an adjacent piezometer. Recompletion of coreholes provides a cost-effective means of acquiring valuable downhole data while eliminating the need to drill a well specifically for monitoring in the same vicinity. Data gathered over the reservoir interval (the Walloon Coal Measures) can inform and help resolve reservoir properties on a regional scale, enhance understanding of the contribution to flow, and provide data points to pressure match a reservoir model. Data gathered over the aquifers within Springbok sandstone and Gubbermunda sandstone enable estimates of any CSG-production effects on groundwater.

In 2009, QGC (a BG Group business), began developing coal seam gas (CSG) feedstock for its new Liquefied Natural Gas (LNG) plant and required a subsurface model and field development plan to underpin the project's investment case. Fundamental to the modeling process was acquiring appropriate data to calibrate subsurface models and enhance confidence in their predictive quality. As part of an integrated reservoir surveillance strategy, specific pressure and temperature monitoring wells were required. This paper describes the successful lab and field implementation of an innovative completion technique that converts suspended coreholes into reservoir and aquifer monitoring wells. The coreholes are re-entered and vibrating wire piezometers (VWP) attached to capillary coil tubing, are positioned and cemented in place alongside selected reservoir intervals. The well is then "plugged and abandoned" and the lease remediated to leave only a small surface footprint for the data logger and telemetry. The cement is effectively impermeable to fluid movement but possesses sufficient permeability to transmit reservoir pore pressure to an adjacent piezometer. Recompletion of coreholes provides a cost-effective means of acquiring valuable downhole data while eliminating the need to drill a bespoke monitoring well in the same vicinity. Data over the reservoir interval (the Walloon Coal Measures) can inform and help resolve reservoir properties on a regional scale, understand contribution to flow and provide data points to pressure-match a reservoir model. Data over the aquifers within Springbok Sandstone and Gubbermunda Sandstone enables estimates of any CSG production effects on groundwater.