Real-time Pore Pressure Estimation via Mechanical Specific Energy
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Solution Overview
Problem
Conventional methods for estimating formation pore pressure during drilling are empirical, predictive limitations, and delayed, affecting drilling efficiency and accuracy due to reliance on d-exponent methods and measurements taken far from the drill bit.
Innovation Solution
Calculating pore pressure in real-time using mechanical specific energy (MSE) and drilling efficiency trends, incorporating downhole drilling mechanics and subsurface rock stress data, providing timely and accurate pore pressure values at the drill bit for improved drilling control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional d-exponent methods are used to estimate pore pressure, then measurements can be taken far from the drill bit, but the pore pressure estimation is delayed and less accurate
Solution Approach 1:
The patent replaces conventional empirical d-exponent methods with a mechanical energy-based approach using Mechanical Specific Energy (MSE). MSE directly measures the mechanical energy required to remove formation material at the drill bit, providing real-time, accurate pore pressure estimates at the actual location of drilling, eliminating both the methodological limitations and time delays of conventional approaches
Solution Approach 2:
The patent introduces Mechanical Specific Energy (MSE) as an intermediary parameter that bridges the gap between drilling mechanics and pore pressure estimation. MSE serves as a direct indicator of formation properties at the drill bit location, enabling real-time pore pressure calculation without relying on delayed or indirect measurements from conventional methods
2Productivity
If real-time pore pressure calculation is implemented using MSE, then drilling efficiency is enhanced, but the system complexity increases
Solution Approach 1:
The system uses existing drilling parameters (weight on bit, rotational speed, rate of penetration, torque) that are already measured during normal drilling operations to calculate Mechanical Specific Energy and pore pressure. This self-service approach leverages data already collected by the drilling system, avoiding the need for additional sensors or complex measurement equipment while achieving real-time pore pressure monitoring
Solution Approach 2:
The patent transforms conventional drilling parameters into Mechanical Specific Energy through a calculated parameter change, where MSE = (Torque × Rotational Speed + Weight on Bit × Rate of Penetration) / (Rate of Penetration × Bit Diameter). This parameter transformation enables pore pressure estimation using standard drilling measurements, enhancing drilling efficiency without requiring complex additional instrumentation
Data Source
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AI summary
A method and system for drilling a borehole in a subsurface formation, A method includes rotating a drill bit to remove formation material from the subsurface formation at an end of the borehole. A value of mechanical specific energy applied to remove the formation material is calculated. A value of drilling efficiency is calculated for drilling the borehole. Pore pressure of the subsurface formation in contact with the drill bit is calculated as a function of the drilling efficiency and the mechanical specific energy. Real-time operational decisions (such as adjusting density of drilling fluid or determining the final depth of the hole section) are made based on calculated pore pressure of the subsurface formation.