Published on 8 March 2019
Case Study : Xpandable Steel external casing packer allows completing multi-stage cementing operations in 10 wells
External Casing Packers (ECP) successfully isolated thief zones, enabling two-stage cementing operations, onshore Argentina
Thief zones encountered downhole are commonly due to fractured or highly permeable formations. These loss zones disrupt the circulation during multi-stage cementing, and can jeopardize the wellbore. Being partial or total, they can also lead to lost circulation. And costing several hundreds of millions of dollars each year in lost or delayed production, remedial cementing.
To limit the potential effect of lost circulation, the operators commonly lessen the density of the cement slurry. Also constrain the friction pressure while pumping, or resort to multiple stage cementing operations. This third alternative consists in combining open hole annulus packers with stage collars, to avoid the thief zone.
An operator in Argentina (Anticlinal Grande field) conducted a multiple-well drilling campaign and required external casing packers (ECP) to perform multi-stage cementing operations. They encountered frequent losses zones while drilling, and needed a cost-effective solution to secure the annulus integrity and cement successfully back to surface.
Schlumberger recommended Saltel Xpandable Steel Packers. A packer had to hold up both in open-hole and deviated and under-gauged holes under tough RIH conditions. The possibility to rotate and put weight on the packer during RIH was also essential.
Saltel Xpandable ECP is specially designed for multi-stage cementing applications.
Xpandable ECPs 5.5in are running sucessfully as annulus barriers in an open hole 9.2in in diameter,to isolate the thief zones and allow a cement stage to add above the packer. The maximum depth of the wells was 8,200 ft [2,500 m], and the setting depth goes from 1,968 to 5,577 ft [600 to 1,700 m].