Abstract
This paper is based on recent job case histories for an operator based in Oman, leading to a case for change.
Operators throughout the Middle East regularly have no option but plan to set casing strings earlier or higher than desired due to problematic geological zones.
Unstable formations can also cause casing runs not to reach depth, resulting in contingency casing strings to be used.
In both of the mentioned scenarios, as a result of being forced to run an additional casing string, the diameter of the well bore through the reservoir could be compromised resulting in a well that is unable to meet production expectations or even reach the planned depths.
The cemented expandable slotted liner is a solution to overcome the issues previously mentioned. For example, if a 9 5/8 in. casing string with an internal diameter of 8.681 in. is set higher than planned due to not being able to get to depth, the cemented expandable cemented slotted liner can be installed below this casing string isolating the problem zone but retaining a through bore of 8.681 in. or larger.
As a result of this technology, operators are able to retain hole size through the next section of the well which could make the difference between the well being commercially viable or not.
In conclusion, there is now a viable alternative to setting contingency casing strings along with a mechanism for operators to consider reducing the number of casing strings that need to be installed to reach target reservoirs. The case histories that will be discussed were completely successful and support the use of the cemented expandable slotted liner in both contingency and planned scenarios.
