Gas Injection While Drilling Pressure Control
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Solution Overview
Problem
Managed pressure drilling (MPD) techniques face challenges in initiating gas injection into boreholes, leading to fluctuations in borehole pressures and fluid flows, which can cause unproductive delays and inefficient gas usage.
Innovation Solution
A method involving the controlled injection of gas into a secondary annulus, with a gas slug pumped down the drillstring and into the primary annulus, allowing the gas to expand and reduce bottomhole pressure while maintaining a steady-state flow, using sensors and processors to regulate the flow rate and pressure to prevent oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If gas injection is initiated into the borehole to reduce bottomhole pressure, then the risk of formation fracturing is reduced, but large oscillations in pressures and fluid flows occur causing unproductive delays
Solution Approach 1:
The system pre-charges the gas injector with gas at controlled rates before initiating gas injection into the borehole. This preliminary action ensures that gas is readily available when needed, allowing rapid response to pressure conditions without causing oscillations or delays during actual injection operations
Solution Approach 2:
The system continuously monitors bottomhole pressure and fluid flow conditions, then adjusts gas injection rates accordingly. This feedback control prevents pressure oscillations by dynamically balancing gas injection with actual borehole conditions, eliminating unproductive delays while maintaining safe pressure levels
2Reliability
If gas is pumped through the drillstring and annulus to control bottomhole pressure, then drilling safety is improved, but gas consumption increases due to inefficient flow management
Solution Approach 1:
The system dynamically adjusts gas flow rates through the drillstring and annulus based on real-time bottomhole pressure conditions. By optimizing flow rates to match actual needs rather than using fixed high rates, the system maintains drilling safety while minimizing unnecessary gas consumption
Solution Approach 2:
The system changes gas flow parameters (rate, pressure, distribution between drillstring and annulus) based on measured bottomhole conditions. This parameter optimization ensures adequate pressure control for safety while reducing excess gas usage through precise parameter matching to operational requirements
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 stabilizes borehole pressures and fluid flows, reducing the risk of formation fracturing and fluid loss, allowing for more efficient drilling operations by maintaining a desired bottomhole pressure within a safe operational window.
Implementation Method 1
a gas slug is pumped down the drillstring and into the primary annulus, allowing the gas to expand and reduce bottomhole pressure
Implementation Method 2
pumping gas down through the drillstring with a flow rate that is equal to the flow rate of the gas that is pumped through the annulus
Data Source
AI summary
Injection of gas into a managed pressure drilling system to provide for operation of the drilling system in a downhole pressure window defined by the pore pressure of a formation being drilled and a fracture pressure of the formation. Gas injection being controlled so as to produce the desired downhole pressure without causing large oscillations in borehole pressure.