Convex Deflector Laser Cutting for Radial Wellbore Slots
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Solution Overview
Problem
In oilfield operations, horizontal wellbores face challenges in hydraulic fracturing due to complex stress states, leading to reduced hydrocarbon productivity as fractures initiate and propagate in vertical planes, resulting in bottlenecks and reduced conductivity.
Innovation Solution
A laser cutting system is introduced to form radial slots in the subterranean formation and casing, using a tool string with a deflector having a convex surface to direct a laser beam, allowing for the creation of transverse fractures that enhance hydrocarbon productivity by initiating fractures in planes perpendicular to the wellbore axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If normal perforations are used in horizontal wellbores under abnormal stress state, then fractures initiate in a plane extending longitudinally relative to the wellbore, but the fractures continue to develop in a horizontal direction which is detrimental to hydrocarbon production
Solution Approach 1:
The patent applies preliminary action by creating radial slots in the formation before hydraulic fracturing. These pre-formed slots provide predetermined pathways that guide fracture propagation in the desired vertical direction, preventing the fractures from developing horizontally along the wellbore axis. The slots are formed using a laser cutting apparatus with a convex deflector that directs the laser beam to cut radial slots extending from the wellbore into the formation.
Solution Approach 2:
The invention segments the fracture propagation path by creating multiple radial slots at different angles around the wellbore. These slots divide the formation into sectors and provide discrete pathways for fracture growth, ensuring that fractures propagate vertically through the formation rather than horizontally along the wellbore, thereby improving hydrocarbon productivity.
2Productivity
If hydraulic fracturing is performed in horizontal wellbores under normal stress state, then fractures propagate along a vertical plane extending longitudinally relative to the wellbore, but at distances further away from the wellbore, the direction of the fractures changes to follow a vertical plane parallel to the direction of the maximum horizontal stress components
Solution Approach 1:
The patent applies preliminary action by pre-forming radial slots that extend vertically into the formation before hydraulic fracturing. These slots establish predetermined fracture pathways that maintain vertical orientation even at distances from the wellbore, preventing the complex bending and direction changes that would otherwise occur under normal stress conditions. This simplifies the fluid pathway geometry and improves productivity.
3Productivity
If a laser beam is used to cut radial slots in the formation, then transverse fractures can be initiated to enhance hydrocarbon productivity, but the laser beam may diverge or defocus over distance reducing cutting effectiveness
Solution Approach 1:
The patent applies spheroidality by using a convex deflector with a curved surface to focus and redirect the laser beam. The convex shape of the deflector concentrates the laser energy onto a precise focal point at the desired depth in the formation, preventing beam divergence and maintaining cutting precision even at long distances from the wellbore. This enables accurate radial slot formation for effective transverse fracture initiation.
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 laser cutting system effectively forms radial slots that improve hydrocarbon productivity by creating transverse fractures, increasing the overall hydraulic conductivity and enhancing oil extraction in horizontal wellbores.
Implementation Method 1
a deflector having a convex surface and disposed for rotation about an axis within the housing, and an optical member conducting a laser beam incident upon the deflector
Data Source
AI summary
A laser cutting apparatus operable in a wellbore to form radial slots in a subterranean formation penetrated by the wellbore. The laser cutting apparatus includes a housing, a deflector disposed for rotation about an axis within the housing, and an optical member conducting a laser beam incident upon the deflector. The deflector has at least one convex surface.