Particulate Buffer for Dissolvable Frac Plug Integrity
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Solution Overview
Problem
Dissolvable frac plugs used in wellbore stimulation dissolve too quickly, failing to provide adequate zonal isolation during multiple stages of wellbore stimulation.
Innovation Solution
A method involving the use of a buffer formed by settling particles, such as calcium carbonate, on dissolvable plugs to attenuate the corrosive effects of stimulation fluids, maintaining plug integrity until all stages are completed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If dissolvable plugs are used in wellbore stimulation, then plug removal cost and time are reduced, but plug durability deteriorates causing premature dissolution before all stimulation stages are completed
Solution Approach 1:
A buffer material is introduced as an intermediary substance between the dissolvable plug and the corrosive stimulation fluid. The buffer attenuates the corrosive effects of the fluid, allowing the plug to maintain its integrity for the required duration while still being removable after completion. This mediator protects the plug during the stimulation process without preventing its eventual dissolution.
2Productivity
If dissolvable plugs dissolve quickly, then plug removal cost and time are reduced, but zonal isolation reliability deteriorates preventing completion of all stimulation stages
Solution Approach 1:
The buffer material is applied to the plug before the corrosive stimulation fluid is introduced into the wellbore. This preliminary protective action ensures that when the corrosive fluid contacts the plug, the buffer is already in place to attenuate its effects, maintaining zonal isolation reliability throughout all stimulation stages.
3Duration of action of stationary object
If buffer material is added to protect dissolvable plug, then plug durability is improved, but device complexity increases
Solution Approach 1:
The buffer material changes the chemical environment parameters around the plug by providing a protective layer that reduces the corrosivity of the stimulation fluid. This parameter change allows the plug to withstand the corrosive effects long enough to complete all stimulation stages while maintaining simplicity in the overall system design.
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
Ensures zonal isolation is maintained throughout multiple wellbore stimulation stages, allowing for efficient fluid production after plug dissolution.
Implementation Method 1
The step of adding a buffer on the dissolvable plug includes disposing a slurry into the wellbore that comprises particles and a suspension fluid. The particles are allowed to fall from the suspension fluid and settle on the dissolvable plug to form a buffer.
Implementation Method 2
The particles are corroded by exposure to the stimulating fluid, which in one example the particles are calcium carbonate. The buffer formed by settling particles attenuates the corrosive effect from the stimulating fluid to the dissolvable plug.
Data Source
AI summary
A wellbore operation for increasing fluid production from a surrounding formation includes multiple stages of wellbore stimulation. In each stage a different zone of the formation is fractured by injecting a stimulation fluid into the wellbore, which creates fractures in the formation zone. Adjacent formation zones are isolated from one another during fracturing by setting plugs in the wellbore between them. On each of the plugs is a buffer that attenuates a corrosive effect on the plugs from the stimulation fluid, and so that the plugs retain sufficient integrity to isolate adjacent zones from one another until all stimulation stages are completed.