Lateral Acid Conduits for Casing Protection
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Solution Overview
Problem
Existing acid stimulation methods for rock formations to enhance hydrocarbon production can cause excessive stress on well casings, leading to potential damage and operational issues due to the collapse of cavities created during the process.
Innovation Solution
A method involving the use of tubing with flexible conduits of smaller diameter than the main tubing, which are advanced into the wellbore and acid is injected through these conduits to create lateral cavities in the rock formation, allowing for enhanced hydrocarbon flow without causing structural damage to the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If acid is injected to create large cavities in the rock formation, then hydrocarbon production is enhanced, but excessive stresses are created on the steel casing causing damage
Solution Approach 1:
The invention divides the single large cavity creation into multiple smaller cavity creations by using multiple conduits distributed around the wellbore. Each conduit creates its own cavity, and the combined effect of multiple smaller cavities collapsing provides the desired production enhancement while distributing and reducing the stress on any single point of the casing.
Solution Approach 2:
The invention nests the conduits within the tubing, which itself is within the wellbore casing. This nested structure allows the conduits to be positioned optimally for cavity creation while being protected during installation and operation, enabling the cavity collapse process without directly transmitting excessive stress to the outer casing.
2Productivity
If tubing or conduits are extended laterally from the main wellbore to distribute acid, then the volume of rock exposed to acid is increased, but the device complexity increases
Solution Approach 1:
The conduits serve multiple functions: they act as acid delivery channels, serve as templates for cavity formation, and remain in place as flow paths for hydrocarbon production. This multi-functionality reduces the need for additional separate components and simplifies the overall system despite the lateral extensions.
3Productivity
If cavities are allowed to collapse to create fractured regions, then hydrocarbon flow is enhanced, but well operations are disrupted due to casing damage
Solution Approach 1:
By segmenting the cavity creation into multiple smaller cavities distributed around the wellbore, the collapse stress is distributed across multiple locations rather than concentrated at a single point. This segmentation prevents catastrophic casing failure while still achieving the desired fractured region for enhanced hydrocarbon flow.
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
This approach creates a highly fractured region for hydrocarbon flow while minimizing the risk of casing damage, as the conduits remain in place, allowing hydrocarbons to flow through the channels created, reducing the likelihood of well operation disruptions.
Implementation Method 1
acid is injected into the formation to dissolve away some of the rock and thereby increase the flow rate and volume of hydrocarbons from the rock
Implementation Method 2
acid injection at high pressure over a relatively short time
Implementation Method 3
when the cavities collapse, e.g. when the well is put on production, this can create excessive stresses on the steel casing
Data Source
Figure 1
AI summary
The invention relates to the completion of hydrocarbon wells using acid. It is known to create cavities in the formation using acid, which then collapse to leave a highly permeable region for production of hydrocarbons. An issue with this technique can be that the wellbore/tubing adjacent the cavity is damaged. The invention involves passing thin conduits through the formation transversely of the main wellbore, through which conduits acid is delivered to create unstable cavities at a distance from the main wellbore thereby stimulating production without risking instability of the main wellbore.