Removal Of The Surface Casing From Wellbores And Creation Of Slots On Dry Wellhead Platforms

摘要

According to the first aspect of present invention there is provided a method of removal of the surface casing from wellbores and apparatusfor performing same. This enables creation of extra slots on dry well head platforms through use of conductor sharing wells technology. According to a second aspect of the present invention, there is provided a rigless method of removing sections of casing. It is known that offshore oil /gas reservoirs have a fixed number of slots on the platforms. Early in the life of field, each of these slots or conductors can be served with single wells to accommodate the high hydrocarbon flow rates at the beginning of the field. In middle to late life, numerous infill wells are drilled by plugging the original wellbore and drilling to new infill locations to increase the hydrocarbon recovery. The liquid rates and the total produced volumes from these infill wells are an order of magnitude smaller than the first wells on the field. The conductor sharing wells then offer a logical way to both increase number simultaneous wells on the platform and address the small liquid rate per well. This however entails removing the surface casing which is usually cemented all the way up to the wellhead.