Slot Recovery

26 March 2009 Dear Dave
Thanks for your feedback.I am working as production engineer looking after work over operation in ONGC Mumbai High Offshore area. I am looking down the alternative of retrieving casing for LDST to relocate the well in prospective undrained area of the reservoir.
We have the following casing policy 30" conductor,
20" casing 300mts
13⅜" casing 900mts
9⅝" casing 2500mts
7" liner 3200mts
9⅝" casing is lowered to top most horizon and 7" liner is landed to landing point to proceed for drilling drain hole where needed.Wells need to relocate for better production once it starts giving water or excessive gas production.For SRDH there is no problem ,it can be done by setting whip stock in 9 ⅝ casing and further reducing hole size to 7" liner. But for LDST wells to achieve a particular drift and direction,it requires cutting of 9⅝ casing below 13⅜ shoe and drilled a fresh 12¼ hole as per the drift and direction and lower a 9⅝ casing .In this course many time 9⅝ does not easily get free after its cutting and many time five to six cuttings are tried to free the casing.Even the cut points are decided based on CBL/VDL/USIT log. To over come this problem , is there any other technology to retrieve casing in very first attempt or to cut casing at seabed and abandoned well accordingly and pile another curved conductor to get a fresh and desired drift and direction in a existing well platform where already eight or nine wells are producing.
May please suggest the prevailing practices worldwide in offshore operations.
Regards,
Nehal Ahmad Siddiqui
GM-Location Manager-Workover
Mumbai High,ONGC,India

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