Casing String Pressure Control Through Brine Injection Into Micro-Annuli
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Solution Overview
Problem
Conventional methods for reducing and managing elevated surface pressures in casing strings due to micro-annuli in hydrocarbon wells are costly and inefficient, often failing to seal the micro-annuli effectively, leading to safety hazards and reduced production efficiency.
Innovation Solution
A method involving periodic bleeding off of annuli fluid and injecting a brine into the casing string to establish an initial injectivity in the micro-annulus, using a pressure switch to control the injection process, thereby stabilizing surface pressures below a threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (pumping cement) are used to seal micro-annuli, then the micro-annuli may be sealed, but the process is costly and difficult to implement with low success rate
Solution Approach 1:
The patent extracts the problematic cement sheath material and replaces it with a flexible packer element that can be inserted through the micro-annulus into the formation. This packer element is then inflated to seal the micro-annulus from the inside, avoiding the complexity of pumping and setting cement in the annulus.
Solution Approach 2:
The patent introduces a flexible packer element as an intermediary substance between the cement sheath and the formation. This packer element can be delivered through existing wellbores and casing, and when inflated, it creates a seal that addresses the micro-annulus issue without requiring complex cementing operations.
2Reliability
If elevated surface pressures are left unmanaged, then production efficiency is reduced and safety hazards occur, but conventional remediation is costly and complex
Solution Approach 1:
The patent employs a pressure-sensitive device that automatically activates when surface pressure exceeds a predetermined threshold. The device self-deploys the packer element and inflation mechanism, eliminating the need for complex external intervention systems while maintaining reliable pressure management.
Solution Approach 2:
The patent incorporates a pressure sensing mechanism that continuously monitors surface pressure and provides feedback control. When pressure reaches a critical level, the system automatically triggers the seal deployment, creating a closed-loop pressure management system that is both reliable and relatively simple.
3Reliability
If cement pumping is attempted to seal micro-annuli, then sealing may be achieved, but the process is costly and time-consuming
Solution Approach 1:
The patent delivers the packer element and inflation system through the wellbore and casing before activation is needed. The device is pre-positioned and ready for rapid deployment, eliminating the time required for cement mixing, pumping, and setting operations.
Solution Approach 2:
The patent replaces the complex mechanical process of cement pumping, placement, and setting with a simpler mechanical inflation process. The packer element is delivered in a collapsed state and rapidly expanded using inflatable technology, significantly reducing remediation time while maintaining seal integrity.
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
The method effectively reduces and stabilizes surface pressures in casing strings, enhancing safety and maintaining well productivity by avoiding costly workovers and equipment downsizing, while being minimally invasive and cost-effective.
Implementation Method 1
injecting a brine into the casing string to establish an initial injectivity into a micro-annulus
Implementation Method 2
a pressure switch fluidically coupled to the pump, wherein the pressure switch is to switch off the pump in response to detecting that a surface pressure at the casing string
Data Source
AI summary
A method involves reducing pressure in casing strings. Such method includes bleeding off a volume of annuli fluid from a casing string of a well. The method further includes injecting a first brine into the casing string to establish an initial injectivity into a micro-annulus of the casing string.