Wellbore Strengthening via Surface Back Pressure Control
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Solution Overview
Problem
The challenge in wellbore drilling is the uncontrollable loss of drilling fluid due to fractures in the wellbore wall, which is exacerbated by uncertainties in mud weight and downhole conditions, leading to uncontrolled fracture growth and increased non-productive time.
Innovation Solution
The method involves using surface back pressure, regulated by a pressure regulator and programmable logic controller, to induce fractures with specific length and width profiles, thereby increasing the fracture gradient and preventing further fracture propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mud weight is used to induce fractures for wellbore strengthening, then fracture initiation can be achieved, but the accuracy and control of fracture dimensions become unacceptably poor
Solution Approach 1:
The patent transitions from using mud weight (density parameter) to using surface back pressure (pressure parameter) to induce fractures. This parameter change enables precise control over fracture initiation and propagation while maintaining reliable fracture creation. The pressure regulator allows independent control of back pressure from mud weight, solving the contradiction between reliable fracture initiation and precise dimensional control.
2Ease of operation
If imprecise pressure control is applied at the wellbore wall, then fracture induction may occur, but uncontrollable fracture growth results in unacceptably large widths and lengths
Solution Approach 1:
The patent employs a pressure regulator with feedback control mechanisms that continuously monitor and adjust surface back pressure. This feedback system maintains pressure within a controlled range, preventing uncontrolled fracture growth while allowing easy fracture induction. The programmable logic controller provides automated feedback control, solving the contradiction between operational ease and dimensional precision.
Solution Approach 2:
The system dynamically adjusts surface back pressure during the wellbore strengthening operation. The pressure regulator can increase or decrease pressure in real-time based on fracture propagation conditions, enabling easy fracture induction followed by precise size control. This dynamic control resolves the contradiction between ease of operation and manufacturing precision.
3Reliability
If conventional wellbore strengthening methods are used, then existing fractures can be sealed, but additional casing strings are required and operational costs increase
Solution Approach 1:
The patent uses precise pressure control to create optimized fracture geometries with controlled length and width profiles. By carefully controlling the induced fracture parameters, the treatment achieves effective fracture sealing without requiring additional casing strings. This parameter control approach reduces device complexity while maintaining sealing reliability.
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 enhances control over fracture growth, reduces the need for additional casing strings, and minimizes fluid loss by applying precise pressure, allowing for more flexible drilling fluid choices and reducing operational costs.
Implementation Method 1
applies surface back pressure to at least one region of the wellbore to induce at least one fracture in the region
Implementation Method 2
seals the induced fracture. The induced fracture has a specific fracture length and width and it increases fracture gradient of the adjacent region
Data Source
AI summary
Systems and methods for wellbore strengthening are disclosed. An effective way to strengthen a wellbore and prevent future fractures during drilling operations is to induce fractures having a desired fracture width profile and fracture length. Surface back pressure can be used to accurately induce such fractures. The induced fractures which are then sealed can increase fracture gradient of the wellbore thus mitigating future fractures.