What are the advantages and disadvantages of using a 'packer' for well completion in a highly fractured geothermal reservoir?

A packer is a downhole tool used to isolate sections of a wellbore. In a highly fractured geothermal reservoir, using a packer for well completion offers both advantages and disadvantages. One advantage is zonal isolation. Packers can isolate specific fracture zones, allowing for selective production or injection. This can improve well performance by focusing on the most productive fractures and preventing water breakthrough from less productive zones. Another advantage is controlling fluid flow. By isolating different fracture zones, packers can help to control the flow of geothermal fluids, preventing commingling of fluids with different temperatures or chemical compositions. This can improve the overall efficiency of the geothermal system and reduce scaling or corrosion problems. Packers can also provide mechanical support to the wellbore, particularly in fractured formations that are prone to collapse. They can help to stabilize the wellbore and prevent casing damage. However, there are also disadvantages to using packers in highly fractured geothermal reservoirs. One disadvantage is the risk of packer failure. Packers can fail due to high temperatures, corrosive fluids, or mechanical stresses. Packer failure can result in loss of zonal isolation and reduced well performance. Another disadvantage is the limited access to the wellbore below the packer. Once a packer is installed, it can be difficult or impossible to access the wellbore below the packer for logging, testing, or stimulation. This can limit the ability to monitor and manage the reservoir. Packers can also restrict flow in highly fractured formations. If the packer is not properly designed or installed, it can restrict the flow of fluids from the fractures into the wellbore, reducing well productivity. Finally, the cost of installing and maintaining packers can be significant. The cost includes the cost of the packers themselves, the cost of the installation equipment and personnel, and the cost of any repairs or replacements that may be required. The decision to use packers in a highly fractured geothermal reservoir depends on a careful evaluation of the advantages and disadvantages, considering the specific characteristics of the reservoir and the objectives of the well completion.