Bit Response Modeling for Rock Abrasiveness and Strength Estimation
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Solution Overview
Problem
Existing methods for estimating rock abrasiveness and strength during drilling are inaccurate due to assumptions of constant drilling efficiency and neglecting cutter wear, leading to inefficiencies in bit performance and drilling conditions selection.
Innovation Solution
A method using bit response data and a bit-rock interaction simulation to calculate mechanical specific energy for pure drilling, accounting for cutter wear and varying drilling efficiency, allowing for precise estimation of rock abrasiveness and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If constant drilling efficiency is assumed in rock property estimation, then calculation complexity is reduced, but measurement precision of rock abrasiveness and strength deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from a static assumption of constant drilling efficiency to a dynamic model where drilling efficiency varies as a function of bit wear level. The system calculates drilling efficiency at different wear stages (e.g., 0%, 25%, 50%, 75%, 100% wear) and uses these varying efficiency values to compute mechanical specific energy, thereby achieving accurate rock property estimation without requiring overly complex real-time variable efficiency measurements.
2Device complexity
If cutter wear is neglected in drilling calculations, then device complexity is reduced, but measurement precision of rock properties deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-calculating drilling efficiency values at various bit wear levels before actual drilling operations. The system establishes a relationship between bit wear level and drilling efficiency in advance, then uses this pre-established model to accurately estimate rock properties during drilling by selecting the appropriate efficiency value based on the current wear level, eliminating the need for complex real-time wear measurements.
3Measurement precision
If dynamic drilling efficiency calculation accounting for cutter wear is implemented, then measurement precision of rock properties is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by transforming the drilling efficiency parameter from a constant value to a variable that changes with bit wear level. The system defines drilling efficiency as a function of wear level (e.g., efficiency at 0% wear, 25% wear, 50% wear, etc.) and uses these parameter variations to accurately calculate mechanical specific energy and estimate rock properties, achieving high precision without requiring complex real-time measurement systems.
Data Source
AI summary
Some implementations include a method which comprises determining a drilling efficiency of a drill bit at a first depth in a wellbore formed in a subsurface formation based, at least in part, on a bit wear level of the drill bit, determining a cutting force mechanical specific energy of the drill bit at the first depth, and determining a rock strength of the subsurface formation at the first depth based on the drilling efficiency and the cutting force mechanical specific energy of the drill bit.