Abstract
Composite bridge plugs (CBPs) save operator time and money by enabling quick and easy installation and removal. CBPs can be installed under pressure in multi-zone, commingled gas wells without using expensive formation kill weight fluids. Kill weight fluids can reduce production from the well, and in some cases have damaged newly fractured zones to the extent that production has been cut in half.
After remedial operations, CBPs can be removed using coiled- tubing-conveyed milling equipment in one fourth of the time required to mill traditional cast iron bridge plugs. Formation damage can be substantially reduced using low viscosity milling fluids that easily remove composite cuttings from the wellbore. This is especially important because of the low annular velocities characteristic of coiled tubing operations. The wellbore is left cleaner than those using cast iron bridge plugs in similar operations.
CBPs can withstand high pressures for up to 10 days without compromising their pressure integrity and without the need for a cement barrier on top of the CBP. Initial field runs have demonstrated that the CBPs can be milled as quickly as 30 minutes compared to 2 hours for milling conventional cast iron bridge plugs. Multi-zone, commingled gas wells using as many as 7 CBPs have been brought back on production after taking only 12 hours to remove all CBPs, including rig-up and rig- down of the coiled tubing unit. Field runs also indicate CBPs can be milled quickly when set at depths exceeding 19,000 feet.
