Predicting Broken-Out Drilling-Induced Fractures in Clay-Rich Formations
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Solution Overview
Problem
Existing techniques for hydrocarbon well drilling and operation fail to account for broken-out drilling-induced fractures (BODIFs), leading to misrepresentation of wellbore instability and potential failure, as they primarily focus on keyseats, washouts, breakouts, and drilling-induced fractures, neglecting the impact of BODIFs on wellbore stability and production efficiency.
Innovation Solution
A method to predict and inhibit BODIFs by determining the minimum circumferential hoop stress, lamination density, clay-rich laminate composition, and linear swelling ratio of the formation rock, using specific drilling fluids, casing strategies, and adjusting production parameters to mitigate the occurrence and effects of BODIFs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing drilling and operation techniques are used that focus on keyseats, washouts, breakouts, and drilling-induced fractures, then conventional wellbore stability monitoring is maintained, but broken-out drilling-induced fractures (BODIFs) are not detected leading to misrepresentation of wellbore instability
Solution Approach 1:
The patent applies preliminary action by calculating a BODIF susceptibility index before drilling operations begin. This index is computed using formation properties (lamination density, clay content, linear swelling ratio) and drilling parameters (hoop stress, wellbore radius, depth) to predict potential BODIF locations and guide preventive drilling and completion strategies
Solution Approach 2:
The patent introduces a BODIF susceptibility index as an intermediary parameter that bridges formation characteristics, drilling conditions, and wellbore stability outcomes. This index serves as a predictive tool that quantifies the likelihood of BODIF occurrence, enabling operators to adjust drilling and completion parameters accordingly
2Ease of operation
If drilling and completion operations proceed without accounting for BODIFs, then operational simplicity is maintained, but wellbore instability and production efficiency are compromised
Solution Approach 1:
The methodology performs preliminary calculations of the BODIF susceptibility index during well planning and design phases, allowing operators to identify high-risk intervals before drilling. This enables proactive adjustment of drilling parameters, mud weights, and completion strategies to prevent BODIFs before they occur
Solution Approach 2:
The patent implements feedback by using the calculated BODIF susceptibility index to continuously guide drilling and completion decisions. As drilling progresses through different formation intervals, the index provides real-time guidance on adjusting operational parameters to maintain wellbore stability and prevent fractures
3Device complexity
If conventional well design and operation methods are used that neglect BODIFs, then design complexity is minimized, but drilling and production stability deteriorate
Solution Approach 1:
The system calculates BODIF susceptibility indices during the well design phase, enabling operators to identify formation intervals prone to broken-out drilling-induced fractures. This preliminary assessment allows for optimized casing placement, cementing strategies, and drilling parameter selection that prevent BODIFs and maintain productivity
Solution Approach 2:
The patent applies parameter changes by adjusting drilling and completion parameters based on the BODIF susceptibility index. When high susceptibility is predicted, the system recommends modifying mud weight, drilling speed, casing depth, or completion pressure to stay below fracture initiation thresholds and maintain wellbore stability throughout production
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 effectively stabilizes the wellbore by preventing BODIFs, enhancing drilling and production stability, and optimizing well design and operation by considering the unique failure mode of BODIFs, thereby improving hydrocarbon extraction efficiency and reducing the risk of wellbore instability.
Implementation Method 1
determining a linear swelling ratio (LSR) of the formation rock
Data Source
AI summary
Determining that a minimum circumferential hoop stress (σθθMIN) of a wellbore drilled into a subsurface formation is less than or equal to a tensile strength (To) of formation rock in the wellbore; determining that a lamination density (DL) of the formation rock is greater than a threshold lamination density (DLthres); determining that a composition of the formation rock is a clay rich laminate; determining that a linear swelling ratio (LSR) of the formation rock is within a specified range; and in response to the determinations, operating the well to inhibit the occurrence of broken-out drilling-induced fractures (BODIFs).