Casing Cutting Technology through Abrasive Water Jet and Its Applications in Offshore Abandoned Wells

In order to efficiently and safely cut casing and structural poles below mudline in offshore wells,abrasive water jet (AWJ) casing cutting technology has been developed to cut abandoned offshore facilities.Based on technical advancement of AWJ cutting through multiple casing strings,hydraulic motor driven and self-rotating water jet cutting device were developed for field applications.Parameters such as jet size,pump pressure,rotation speed,abrasive material types,etc.were optimized through systematic laboratory tests and abrasive water jet cutting technique was formed.Full scale surface and downhole tests in the offshore Well CFD1-6-1 showed that this AWJ cutting device could cut through 4 cemented casing strings (sizes:φ244.5,φ339.7,φ508.0 and φ762.0 mm) in less than 6 hours,which met field application requirements.In addition,the system is compatible with engineering support vessel instead of mobile offshore drilling units so as to further reduce its cost.Its practical application shows the AWJ device with advantages as strong cutting capability,high cutting efficiency and environmental friendliness,would provide a new offshore technical solution to abandonment of offshore oilfield facilities and structures in China.