Subsea Casing Drilling Depth Optimization
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Solution Overview
Problem
Current subsea drilling practices often result in first casings being placed too shallow in the geological formation, leading to insufficient structural support, fracture resistance, and leak-off tolerance, which can cause drilling hazards and reduce hydrocarbon production by requiring additional casings, ultimately narrowing casing diameters and increasing drilling fluid friction.
Innovation Solution
The proposed systems and methods involve optimizing the placement of casing seats by positioning the first casing at greater depths, using real-time data on pore pressure and fracture pressure to determine the optimal depth for each casing, thereby enhancing axial support and reducing the number of subsequent casings needed, allowing for larger diameters and improved hydrocarbon production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the first casing is placed at a shallow depth to avoid geological hazards, then the casing seat placement is simplified, but the structural support and fracture resistance are insufficient
Solution Approach 1:
The patent applies preliminary action by placing the first casing at a greater depth than traditionally required, proactively ensuring sufficient structural support and fracture resistance before drilling operations proceed. This preliminary depth placement prevents later complications from insufficient support, eliminating the need to relocate casing seats due to drilling hazards.
Solution Approach 2:
The patent changes the critical parameter of casing depth from shallow to greater depth. This parameter change transforms the first casing into an effective structural support element that can withstand bending moments and provide fracture resistance, while still allowing casing seats to be placed above geological hazards.
2Ease of operation
If the first casing is placed at a shallow depth, then the initial drilling operation is simplified, but additional casings are required increasing device complexity
Solution Approach 1:
By proactively placing the first casing at a greater depth during the initial drilling operation, the patent eliminates the need for subsequent casing installations. This preliminary action consolidates multiple drilling operations into one, reducing overall device complexity while maintaining ease of operation.
3Strength
If additional casings are required due to shallow first casing placement, then structural support is improved, but casing diameters are reduced increasing drilling fluid friction
Solution Approach 1:
The patent uses preliminary action by placing the first casing at greater depth to provide adequate structural support from the outset. This prevents the need for additional casings that would progressively reduce diameter and increase drilling fluid friction, maintaining larger annular spaces throughout the wellbore.
4Strength
If the first casing is placed at greater depth, then structural support and fracture resistance are enhanced, but the drilling operation becomes more complex
Solution Approach 1:
By placing the first casing at greater depth as a preliminary action, the patent consolidates multiple drilling and casing operations into a single operation. This actually reduces overall device complexity despite the increased initial depth, as it eliminates the need for subsequent casing installations and associated operations.
5Reliability
If casing seats are placed above geological hazards, then drilling hazards are avoided, but the number of casings increases reducing hydrocarbon production
Solution Approach 1:
The patent applies preliminary action by placing the first casing at greater depth before encountering geological hazards. This allows casing seats to be positioned above hazards while maintaining adequate structural support, eliminating the need for additional casings and preserving hydrocarbon production capacity.
Solution Approach 2:
By changing the depth parameter of the first casing to greater depth, the patent enables casing seats to be placed above geological hazards without requiring additional casings. This parameter change maintains both drilling safety and production efficiency.
Data Source
AI summary
Systems and methods for casing drilling riserless sections of a subsea bore may include casing drilling a section of a bore for a casing of the subsea bore to a predetermined depth. The method also may include, while casing drilling the section of the bore, obtaining information indicative of pore pressure and fracture pressure of a geological formation through which the section is casing drilled, and determining a pressure range based at least in part on the pore pressure, the fracture pressure, and a modification to mechanical properties of the geological formation due to the casing drilling of the section. The method further may include selecting, based at least in part on the pressure range and the predetermined depth, a pressure of the bore for casing drilling the section.