![WELL STRUCTURE: Graphic supplied by Beach Energy WELL STRUCTURE: Graphic supplied by Beach Energy](/images/transform/v1/crop/frm/silverstone-agfeed/2044279.jpg/r0_0_600_400_w1200_h678_fmax.jpg)
A BEACH Energy spokesperson says high-pressure gas hitting cement well casings will not inhibit bonding.
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Wells consist of three layers of cemented steel, and those that are installed over shallow aquifers are installed first and within the first few days of drilling before gas bearing intervals are intersected.
"The drilling continues from within this surface casing, towards the target intervals," the spokesperson said.
"A second, narrower layer of cemented steel casing is installed just above the zones of interest and this is also cemented to the surface, again in the absence of gas-bearing intervals."
Each cement job was checked to confirm cement returns to the surface and casing layers were pressure-tested before drilling continued to the next stage.
The well was then drilled through the target intervals, with all higher intervals isolated behind pipes and the final layer of casing again cemented to the surface.
"At the conclusion of drilling, the shallow intervals where surface aquifers occur end up behind three casing strings that are cemented to surface," the spokesperson said.
"This is an important and essential process to ensure we develop high-integrity wells that cannot communicate with surface aquifers."
Cement integrity was "confirmed" with a cement bond log and, if potentially corrosive carbon dioxide had been observed underground, special steel materials designed to withstand it would be used in a fourth layer of steel.
*Full report in Stock Journal, October 24 issue, 2013.