Safe Drilling Fluid Density Calculation in Fractured Formations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for calculating drilling fluid density in fractured formations are inadequate as they fail to consider geometric factors, leading to instability and potential wellbore collapse during drilling.
Innovation Solution
A method involving image processing to identify downhole fractures, establishing 3D geological models, and using the 3DEC discrete element code to determine safe drilling fluid density by iteratively updating bounds until stability conditions are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If continuous medium theory is used to calculate well-wall stress, then the calculation process is simple, but it cannot consider the effects of geometric occurrence of formation on well-wall stability in fractured zones
Solution Approach 1:
The patent segments the continuous rock mass into discrete blocks separated by fractures. The 3D distinct element model divides the formation into individual rock blocks that can move independently, allowing the geometric occurrence of fractures to be explicitly considered in the well-wall stability calculation, thus resolving the limitation of continuous medium theory.
Solution Approach 2:
The patent transitions from 2D fracture representations to 3D geological models. By establishing three-dimensional distinct element models that incorporate the spatial geometry of fractures, faults, and bedding planes, the system accurately captures the complex geometric occurrence of formation features that affect well-wall stability.
2Stability of the object's composition
If drilling fluid density is increased to support wellbore in fractured zones, then wellbore stability improves, but the risk of inducing formation fracture and wellbore collapse increases
Solution Approach 1:
The patent employs an iterative feedback mechanism where the 3D distinct element model simulates wellbore construction with specific drilling fluid density, evaluates well-wall stability, and adjusts the density accordingly. This feedback loop continues until the optimal drilling fluid density is found that maintains wellbore stability without inducing formation fracture or collapse.
Solution Approach 2:
The patent systematically varies the drilling fluid density parameter in the 3D distinct element model to find the optimal value. By changing this critical parameter and observing its effect on well-wall stability through numerical simulation, the method identifies the precise density range that prevents both wellbore collapse and formation fracture.
3Measurement precision
If 3D distinct element model with image processing is used to calculate drilling fluid density, then calculation accuracy in fractured formations improves, but computational complexity and time increase
Solution Approach 1:
The patent performs preliminary image processing of formation logs to identify and characterize fractures, faults, and bedding planes before constructing the 3D distinct element model. This preliminary action extracts geometric parameters of formation features from images, which are then used to build an accurate numerical model, reducing the complexity of direct 3D modeling while maintaining high calculation accuracy.
Data Source
AI summary
The present disclosure discloses a method for calculating a safe drilling fluid density in a fractured formation, including the following steps: S1, performing image processing to identify a downhole fracture; S2, establishing three-dimensional (3D) geological models based on parameters of the downhole fracture, and establishing a drilling wellbore model based on a size and length of a wellbore; S3, assigning the model with material parameters, boundary conditions, and upper and lower bounds of an initial drilling fluid density, and calculating accuracy; S4, solving the 3D geological models using a 3-dimension distinct element code (3DEC) and determining stability of a well wall; S5, determining upper and lower bounds of a drilling fluid density using dichotomy; S6, repeating steps S4 to S5; and S7, after set accuracy conditions are reached, saving and outputting the safe drilling fluid density.