Filtration Of Completion And Workover Fluids

Weighted brines are commonly used to prepare oil and gas producing wells for completion and the initiation of production. These brines are often referred to as completion fluids. The proper type and concentration of brine is required in order to prevent blowouts and ensure well safety by balancing the formation pressure. If the system is under-balanced, when the formation pressure is greater than the well bore, oil and gas will enter the "hole" endangering the rig and crew. As a result, most work is performed in a slightly over-balanced situation, where the fluid pressure in the hole is slightly greater than the formation pressure. When over-balanced, large volumes of expensive brine may be lost to the formation. Since these fluids will come in contact with the formation, perforation and gravel pack, it is important that they be free of suspended solids so that they do not damage or reduce the permeability of these production zones.

Workover fluids are similar to completion fluids except that they are used when an already completed well requires maintenance in order to increase its productivity. A well bore may be "swabbed" and reperforated through the workover fluid as part of this operation. As with completion fluids, it is important that they be free of suspended solids that can reduce the permeability of the production zone formations.

This CUNO Application Brief will discuss the benefits of using cartridge filtration to reduce the level of total suspended solids in completion and workover fluids, resulting in reduced formation plugging and increased production.