Perforating Gun Bridge Sub Fluid Displacement
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Solution Overview
Problem
Formation damage during wellbore perforation operations occurs due to initial fluid ingress caused by high pressure transients during shaped charge detonation, and existing methods for creating a dynamic underbalanced condition are inefficient, requiring multiple trips and increased safety risks.
Innovation Solution
A single trip perforation system that includes a working string with a perforating gun, upper and lower bridge subs, and a discharge flow port, allowing for the displacement of completion fluid with a lighter density treatment fluid using exterior conduits to create a controlled fluid displacement path, reducing the need for additional trips and minimizing formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shaped charges are detonated to create perforations through casing and cement, then hydraulic openings are created for fluid production, but high pressure transients cause formation damage due to fluid ingress
Solution Approach 1:
Treatment fluid is pumped through the working string to displace completion fluid from the perforation zone before the shaped charges are detonated. This preliminary displacement action ensures that when high pressure transients occur during detonation, the treatment fluid (which is formation-compatible) is already in place to prevent formation damage, rather than allowing completion fluid to ingress into the formation
Solution Approach 2:
Treatment fluid acts as an intermediary substance between the completion fluid and the formation. By displacing completion fluid with treatment fluid that has favorable properties (lower density, formation-compatible), the patent creates a protective barrier that mediates the harmful interaction between high pressure transients and the formation, preventing direct contact between completion fluid and formation pores
2Object-affected harmful factors
If treatment fluid is pumped through the working string to displace completion fluid, then formation damage is reduced, but additional trips and operational complexity are required
Solution Approach 1:
The working string is designed to serve multiple functions: it acts as both the conveyance for the perforating gun system and as the fluid delivery system for pumping treatment fluid to the perforation zone. The exterior conduits on the working string provide dual pathways for fluid circulation. This multi-functionality eliminates the need for separate displacement operations or additional trips, reducing operational complexity while maintaining formation protection
Solution Approach 2:
The patent combines the perforating operation and the fluid displacement operation into a single integrated process. The treatment fluid displacement and the perforating gun deployment are merged into one trip down the wellbore, with both functions executed through the same working string system. This merging of operations eliminates the need for separate trips that would otherwise be required
3Productivity
If treatment fluid flow rate is increased to accelerate displacement, then operational time is reduced, but channeling effects occur resulting in incomplete displacement
Solution Approach 1:
The exterior conduits are positioned at specific locations along the working string to create localized fluid injection points. This spatial distribution of fluid delivery creates more uniform flow patterns throughout the annulus, preventing channeling effects that would occur with single-point injection. The local quality of fluid introduction is optimized at multiple positions to ensure stable and complete displacement
Solution Approach 2:
The system allows for dynamic adjustment of treatment fluid flow rate during the displacement process. By controlling and modulating the flow rate rather than maintaining a constant high rate, the patent achieves stable displacement that prevents channeling while still maintaining efficient operational timing. The dynamic control of flow parameters optimizes both productivity and displacement uniformity
4Reliability
If perforating is conducted in overbalanced pressure condition for safety, then uncontrolled fluid flow is prevented, but formation damage still occurs due to high pressure transients
Solution Approach 1:
Treatment fluid is pumped to displace completion fluid from the perforation zone before detonation occurs, while maintaining overbalanced pressure conditions for safety. This preliminary action prepares the formation environment with formation-compatible fluid in place, so when the shaped charges are detonated under safe overbalanced conditions, the treatment fluid prevents formation damage that would otherwise occur from completion fluid ingress
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient displacement of completion fluid with a formation-compatible treatment fluid, reducing formation damage and operational risks while maintaining a controlled pressure condition, suitable for both overbalanced and underbalanced operations, and compatible with fluid-sensitive formations.
Implementation Method 1
displacing a completion fluid with a lighter density treatment fluid
Implementation Method 2
detonating a series of shaped charges that are disposed within hollow steel carriers
Implementation Method 3
a series of shaped charges that are disposed within hollow steel carriers and positioned within the casing string adjacent to the formation
Data Source
AI summary
A single-trip method and system for perforating casing allows displacement of a heavier completion fluid from the perforation zone by a lighter formation-compatible treatment fluid without the need for an extended rat hole or repositioning the working string. The perforating system includes bridge subs located above and below a perforating gun. The bridge subs bypass treatment fluid around the gun through one or more conduits located along the exterior of the gun into a discharge flow port located immediately below the lower bridge sub. The system may be hydrodynamically designed to maintain efficient fluid displacement characteristics of the discharge flow port. The external conduits are positioned to not interfere with perforation operations and may include parallel conjoined tubes. The perforating system may be lowered to a perforation position in the wellbore, and treatment fluid pumped through the discharge flow port to displace completion fluid prior to perforation operations.