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 cementing, and can jeopardize the wellbore. Being partial or total, they can also lead to lost circulation, costing several hundreds of millions of dollars each year in lost or delayed production, remedial cementing, or in solving drilling issues.
To limit the potential effect of lost circulation, the operators commonly lessen the density of the cement slurry, 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 2-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.
Selecting Saltel Xpandable Steel ECP
Schlumberger recommended Saltel Xpandable Steel Packers. The packers were to be set either in openhole and had to withstand tough RIH conditions in deviated and under gauged holes. The possibility to rotate and put weight on the packer during RIH was also essential.
Saltel Xpandable ECP is specially designed for stage cementing applications.
10 Xpandable ECPs 5.5in were run and installed as annulus barriers in 9.2in open hole, to isolate the thief zones and allow a second cement stage 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].
The cementing campaign recorded 100% success with Saltel Xpandable Steel Packers. The 10 packers isolated the troublesome lost circulation zones, and allowed resuming cementing operations. The cement could be pumped back to surface through a stage collar above the ECP.