Microannulus Leaks Repaired With Pressure-Activated Sealant

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 91399, "Microannulus Leaks Repaired With Pressure-Activated Sealant," by David W. Rusch, SPE, Seal-Tite Intl.; Fred Sabins, SPE, Cementing Solutions Inc.; and John Aslakson, SPE, W&T Offshore Inc., prepared for the 2004 SPE Eastern Regional Meeting, Charleston, West Virginia, 15-17 September. Sustained casing pressure (SCP) is a serious problem that is prevalent in most of the oil-producing regions of the world. Annular pressure can be a significant safety hazard and has resulted in blowouts on a number of occasions. SCP is the result of fluid migration in the annulus. The most common path for fluid migration is through channels in the annular cement. An injectable pressure-activated sealant was used to seal channels in the annular cement of several wells in the Gulf of Mexico (GOM). Introduction Fluid migration through the annuli of well-bores can result in a condition known as SCP. SCP is pressure that rebuilds in the annulus after being bled down. The integrity of all wellbores deteriorates with age. Cracks and fissures caused by factors related to cement composition, thermal stress, hydraulic stress, and compaction develop in the annular cement. The most significant cause of SCP in outer casing strings is a poor cement bond that results in cracks and annular channels. The cracks and microannulus channels provide a path for high-pressure fluids to migrate. A significant flow of high-pressure fluids can result in an underground blowout or failure of wellbore integrity.