Filters with Dissolvable Plugs
A technology for staged opening of channels in downhole filters: the filter openings are initially blocked by plugs made of a dissolvable material (e.g., magnesium, aluminum or a special compound) that dissolve on purpose under the action of a reagent (acid, mineralized water, etc.) or under set conditions (temperature, pressure).
Advantages
- Fewer trips (POOH/RIH) and shorter well-construction time. Dissolvable plugs remove the need to retrieve temporary elements mechanically: they dissolve on their own under the set conditions. This saves time and reduces labor intensity.
- Protection of the productive formation during completion. The plugs temporarily isolate the filter from process fluids and solids, reducing the risk of plugging the bottomhole zone and preserving the well’s potential rate.
- No additional filter-normalization operations. Once the plugs dissolve, no milling, flushing or other intervention is required to open the flow ports — the system is ready for operation.
- Applicability in complex wells. The technology allows liners to be run in ERD wells (with a large horizontal departure) and in other conditions where conventional isolation methods are less effective or inapplicable.
- Predictable and controllable dissolution. The dissolution rate is selected for specific conditions (fluid composition, temperature, pressure); if necessary the process can be accelerated by pumping special compounds (e.g. acid blends).
- Lower risk of equipment damage. Unlike knock-out caps, dissolvable plugs leave no solid fragments that could damage pumps or other downhole equipment.
Specifications
- filter element length: from 6000 mm
- nominal slot gap: 150 µm
- total filtration area: 38%
- performance class: V3
- quality class: Q3
Application area and experience
- Completion of oil and gas wells with filter installation. Dissolvable plugs are used within downhole filters for staged commissioning of individual reservoir intervals.
- Inflow control systems (ICD, AICD, etc.). The technology makes it possible to temporarily block sections of inflow-control devices and activate them later after the plugs dissolve.
- Multistage hydraulic fracturing (MSF). Dissolvable elements are used in assemblies to isolate intervals during fracturing, with subsequent automatic opening after the operation.
- Temporary interval isolation during drilling and completion. The plugs separate the tubing and annulus during process operations and then dissolve without requiring retrieval.
- Wells with complicated operating conditions. The technology is in demand in horizontal and highly deviated boreholes, in zones with a sand-production risk and in other cases where reliability and minimization of downhole work matter.