workover patch vs casing perforations

SPE-201432-MS – Water Isolation and Sand Control

Published on 22 October 2020

Breaking Barriers with Expandable Steel Casing Patch Technology


This paper describes the design, planning, and successful installation of a fit-for-purpose Casing Patch to isolate a water producing zone, the subsequent perforation of an adjacent zone, and a gravel pack completion in the same well for the first time worldwide. The proximity of the zones and the sand control requirements made the design and planning of this job a challenging task that is detailed in this manuscript.

The main producing zone in the SW-21 well watered out after few years of production. A second target was identified located just four feet below the main zone. To extend the life of the well and to add reserves from the secondary target, the upper 100% water zone had to be isolated. A fit-for-purpose, thin wall stainless steel patch solution was designed to: allow perforation of the secondary target while maintaining patch integrity, allowing for the installation of sand control screens; and resist following gravel pack completion, by keeping the minimum recommended clearance between casing and screens, inside the minimal patch-reduced diameter.

The re-completions program consisted of: 1. Successful recovery of existing gravel pack from the main producing zone and thorough wellbore cleanup. 2. Expandable steel patch installation consisting of a 23-ft long patch to isolate the water-producing zone. In this case, a specific engineering design analysis was required to ensure that, because of the very close distances between zones, the patch would still maintain integrity during perforation of the secondary target and the resulting patch overlap. 3. Successful integrity test to confirm upper interval isolation before perforating the lower interval. 4. A precise perforating operation carried out to perforate the secondary zone. Based on engineering recommendations, some length of the installed patch was perforated to guarantee a minimum unperforated distance of patch between zones to guarantee patch sealing features. 5. Once perforation was successfully accomplished, a gravel pack completion—inside the patch reduced diameter—was executed along the new zone for sand control purposes, and the well was put into production.

This paper presents the different interactions between a multidisciplinary research and development team, and completions and reservoir engineers to come up with a full solution for water isolation and sand control under such challenging conditions. For the first time in the world, a patch was used to isolate a water zone, and at the same time, perform a gravel pack completion inside the patch reduced diameter. Well performance, without any mechanical issues, confirms the success of the provided solution.

Read more in OnePetro

isolate perforations

Ximena Guerrero (Schlumberger) | Daniel Ricardo Medina (Schlumberger) | Alberto Munoz (Hocol S.A.) | Jhon Rubiano (Hocol S.A.) | Alied Bejarano (Hocol S.A.) | Hernando Trujillo (Hocol S.A.) | Nicolas Saltel (Schlumberger) | Julian Trillos (Schlumberger) | Jerson Becerra (Schlumberger) | Diego Castellanos (Hocol S.A.) | Cesar Coronado (Hocol S.A.)

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