The primary goal of surface isolation in well completion and intervention activities is to reduce the costs associated with the completion process. Therefore, this practice is generally reserved for wells that do not require an artificial lift or have a short production life. A subsea test tree is used for this as well. However, there are several benefits of using a perforated casing completion. We will discuss the advantages and disadvantages of each. Listed below are the advantages and disadvantages of each type of completion.
Disadvantages of an Open Hole Completion
Despite the advantages of an open hole completion, it still has drawbacks. For example, an open hole is prone to collapse, and installing down-hole pumps and production tubing into an unlined well is often frowned upon by production engineers. Similarly, multiple seams in the open hole make it challenging to control stimulation and cleanup activities. However, it has a more positive impact than the C&P concept regarding personnel HS&E exposure.
Another disadvantage of an open-hole completion is its limited production capability. The open hole completion cannot meet the requirements of fracturing stimulation. A wellbore made of carbonate rock is likely to contain mud shale interbeds, which collapse when they encounter water and plug the wellbore. This means the open hole completion may not be ideal for a sandstone reservoir.
Prevention of Wellbore Collapse
The prevention of wellbore collapse by surface isolation during well completion and intervention activities is vital for successful production and depletion. The wellbore is the only path to the reservoir and must be fully functioning to ensure a high production level. Therefore, a production engineer designed and supervised all completion and workover operations. These engineers must understand the physics of fracture mechanics and the wellbore’s role in forming oil and gas reservoirs.
There are three main types of completions: perforated casing completion, open hole completion, and liner and cement job. Perforated casing completion is the most common type of completion. However, it is also possible to use alternate perforated casing completions under certain conditions. The choice of completion should match the reservoir management plan. The size of the tubular goods is also dependent on the ultimate use. For example, an injection well may require a more robust casing than a production well.
Minimization of Workover Costs
Well completion and intervention activities include using surface isolation to protect the reservoir. The objective is to prevent damage to the reservoir and the production process while minimizing the need for workovers. The isolation valve is used in various activities, including batch drilling and well suspensions, ESP workovers, and underbalanced perforating. It is also commonly used to control fluid loss and downhole lubricator valves.
The design of a well completion must be flexible to account for possible changes in production. It should incorporate components that are easy to work with and anticipate different operating conditions. A well completion with the lowest cost should perform as intended throughout the well’s life. However, a completion design with less flexibility may have fewer benefits than a simpler one. Therefore, it is best to use multiple completions only in particular situations, such as in areas with high drilling costs. You can also learn more through service providers such as PRT Offshore.
Benefits of a Perforated Casing Completion
Perforated casing completion is a critical ingredient in today’s well-completion processes. It allows producers to select the reservoir fluid they want to inject while isolating all zones from reservoir fluid that flows into the wellbore. The method also provides selective injection and production, as sliding sleeves allow open and closed zones. However, the process does require additional costs for casing and completion equipment.
A perforated casing is a drilling casing set above the zone of interest. It allows for an accessible cleanout and minimal formation damage. Perforations can help a well get deeper but make it difficult to control water and gas buildup. They may also require more rig time and may require frequent cleanouts. However, a key advantage is that perforated casing completion is relatively inexpensive.
