hi haasko, you have to keep it simple here lol. correct in your...

hi haasko, you have to keep it simple here lol. correct in your comments and its pretty straight forward to understand casing basically ensures a pressure-tight connection from the surface to the reservoir (hopefully to our oil prone Tirrawarra), prevents contamination, cave ins, controls well pressure and confines the production to the well bore. The protection of acquifiers from invasion of well bore fluids although important environmentally is not really applicable in this area, its more so a concern where groundwater serves nearby industry and populations etc. I'd like to think natural soil filtration would take place by the time any groundwater reached a user destination from the Simpson? Unless of course there was an oasis nearby which camels drank from as we know theres alot of camels out there :)

Any loss of fluid into surrounding mediums however does raise numerous problems as drilling fluid serves several purposes. Most importantly it provides a weight to assist in maintainng underground pressures and is the first line of control in preventing any "blowouts" which after this the rigs BOP comes into play and as noted the mud obviously brings any cuttings to surface and also cools the bit etc, Any losses of the mud will have adverse impacts on well pressure control. The last thing any driller needs is a cave in or loss of control with subsequent well damage and bit recovery problems. The lapindo/santos issue in east java I believe is one of the worse case scenarios of what can happen with loss of control via a blowout but those guys we're just careless. It is time consuming to run and cement the casing but it is very important as noted. One of the reasons it can be time consuming is that its imperative the correct amount of torque is applied to prevent any tension failures and abnormal pressure surges that can break formations and even cause circulation problems in cementing. The cementing then basically bonds the metal casing to the rock formation and used to separate the horizons from eachother, prevent corrosion from waterbearing mediums and to anchor the casing in the hole. I believe its also important to anchor the rigs valves, control head and blowout prevention equipment and allows safer use of drilling tools.

Anyways, being the wildcat area it is central will no doubt be as cautious as possible. JH has waited 10 years for this so taking a few extra days in drilling im sure wont bother him one little bit :)